Misfire detection based on exhaust manifold pressure for internal combustion engines

Abstract

Method for detecting a cylinder misfire in an internal combustion engine having at least one cylinder, comprising: Comparison of a first load variable (FLV) with a first estimated load variable (FELV) for a first cylinder of the engine; determining a first process, wherein the first process is an estimated exhaust manifold pressure process (EEMPP) or a centroid projection process (CPP), and wherein the CPP is at least partially based on an estimated exhaust manifold pressure (EMP); In response to the determination of the first process, an operating value (OV) is calculated with respect to one or more data inputs of the engine characteristics and a comparative value (CV) associated with a threshold, wherein the OV and the CV are calculated using either the EEMPP or the CPP; Comparison of the OV with the CV, and Detection of a misfire condition for the first cylinder based on the comparison of the OV with the CV.

Description

FIELD OF THE INVENTION

[0001] This invention is directed generally to the field of internal combustion engines, and more particularly to a system and method for detecting engine cylinder misfires under a range of operating conditions in such internal combustion engines. GENERAL STATE OF THE ART

[0002] Engine manufacturers have developed techniques for constantly monitoring engine operating data to determine when engine operation is abnormal or outside of specified tolerances. Engine manufacturers have sought methods and procedures to detect or predict when abnormal operation may occur, in an attempt to meet the demand for increased internal combustion engine efficiency and improved emission control. Likewise, providing methods that can identify abnormalities in operation early on can help prevent damage and avoid potentially costly internal combustion engine repairs.

[0003] An engine cylinder misfire (i.e., a misfire) is an example of such an event. Engine manufacturers attempt to detect the occurrence of a misfire because a detected misfire may be an early sign of a potential problem with engine operation. For example, a cylinder misfire may occur as a result of failed ignition of the fuel-air mixture within an engine cylinder (lack of combustion) or as a result of incomplete ignition of the fuel-air mixture caused by an overly lean mixture (incomplete combustion). If such a misfire occurs during operation, the affected engine power will be reduced, emissions will likely be increased, and fuel economy will be reduced. If a misfire is not corrected, it can also lead to damage to the engine and its components, including, for example, damage to the catalytic converter.

[0004] Furthermore, the detection of engine cylinder misfire is a prerequisite for on-board diagnostic systems (e.g., OBD II, HD ODB, etc.). OBD II, for example, is a second-generation requirement for on-board self-diagnostic equipment that provides the capability to monitor engine components that can affect emissions performance, such as engine misfires. An OBD II system typically also stores important information about a detected malfunction, such as the engine cylinder misfire and the faulty cylinder or component.

[0005] Engine manufacturers have used a variety of methods to detect engine misfire, but none of the state-of-the-art methods consider a large number of existing operating conditions of an internal combustion engine, including exhaust manifold pressure (EMP) with information from other sensor data such as engine speed, boost flow (or mass air flow (MAF)), exhaust gas recirculation (EGR) pressure, ambient pressure, turbine speed, and turbine position to detect engine misfire.

[0006] For example, U.S. Patent No. 5,193,513 to Marko et al. discloses a misfire detection system for use with an internal combustion engine that utilizes an exhaust pressure sensor, a position sensor for sensing the rotational position of the engine, and an analog-to-digital converter for digitizing an analog signal received from the pressure sensor. The digitized pressure data is compared using a data classifier (i.e., a pattern recognition system) configured to recognize data signatures of individual misfiring cylinders. To train the classifier, the engine is operated in a service area, and engine data is collected during both intentionally induced misfires and under normal conditions. This data is then presented to the data classifier in a learning session. Engine misfire detection systems, such as the system disclosed by Marko et al.disclosed, however, do not compare the multitude of engine parameters with the detected engine cylinder pressure peaks as a way to detect partial or complete engine misfires.

[0007] US Patent No. 3,965,677 to Goto et al. discloses a misfire detecting device in which the intake pressure of an engine is detected and used to calculate a threshold, wherein a cylinder misfire is declared to have occurred when the exhaust pressure exceeds this threshold.

[0008] US Patent No. 3,983,754 to Deguchi et al. discloses a misfire detection device in a multi-cylinder internal combustion engine in which pressure-responsive devices are provided in the exhaust manifold tubes or in the exhaust manifold ports, and the outputs of these devices are compared to detect engine cylinder misfire.

[0009] U.S. Patent No. 4,567,755 to Ootsuka et al. discloses an ignition / misfire detector for an internal combustion engine in which a pressure detection unit is used to detect changes in combustion pressure in the engine, and an ignition / misfire detection unit is used to detect the occurrence of an engine misfire.

[0010] U.S. Patent No. 3,924,457 to Oshima et al. discloses a misfire detection device for an internal combustion engine in which an exhaust gas introducing pipe is provided adjacent to an exhaust port in an exhaust passage for supplying exhaust gas to a pressure sensor disposed at one end of the exhaust gas introducing pipe to detect pressure fluctuations that may indicate a possible engine cylinder misfire.

[0011] In OBD II systems, many current monitors use crankshaft speed variations to detect misfires. However, it is generally recognized that the use of crankshaft speed variations depends on the powertrain and vehicle dynamics. Such dependence, including that using engine speed, is limiting, as there is no transferability of detection between different applications, and the input data is often negatively affected by driveshaft dynamics.

[0012] These state-of-the-art engine cylinder misfire detection methods lack the unique approach of utilizing a variety of existing engine operating conditions, including the use of a relationship between in-cylinder pressure, changes in EMP fluctuations, and other operating conditions to obtain an efficient engine cylinder misfire detection system.

[0013] A novel engine cylinder misfire detection system and an improvement over the prior art is disclosed in U.S. Patent No. 5,392,642 to Tau, a patent assigned to Cummins Engine Company, Inc., the same patent owner as the present invention. This patent discloses an engine cylinder misfire system that uses a sensor to monitor an engine cylinder over all engine cycles and provide an average of the detected outputs for all cylinders. In addition, engine speed and fuel consumption of the internal combustion engine are utilized to provide a more efficient engine cylinder misfire detection system. However, the invention disclosed in the Tau patent is directed to a system for detecting low power in at least one cylinder of a multi-cylinder engine.Furthermore, this application discloses the use of multiple pressure sensors, specifically one sensor for each cylinder, to provide engine misfire detection.

[0014] Another novel engine cylinder misfire detection system and an improvement over the prior art is disclosed in U.S. Patent No. 6,243,641 to Andrews et al., incorporated herein by reference, a patent assigned to Cummins Engine Company, Inc., the same patent owner as the present invention. This patent discloses an engine cylinder misfire detection system that uses pressure sensing means for sensing a pressure peak of the exhaust gas flowing through the exhaust and internal combustion engine operating data to calculate and compare a minimum pressure value to determine whether an engine cylinder misfire has occurred.

[0015] Other approaches have been presented, but these methods still lack the ability to detect engine cylinder misfire by applying a relationship between the in-cylinder pressure, changes in EMP fluctuations, and other operating conditions to provide an efficient engine cylinder misfire detection system that is operable in a variety of operating environments (i.e., powertrains, vehicles, etc.), can be calibrated for many different applications, and is reliable under a variety of operating conditions.

[0016] In contrast, the inventor recognized the need for an engine cylinder misfire detection system that detects changes in EMP fluctuations, compares the EMP fluctuations to diagnostic thresholds established with other information from other engine sensor data, and detects whether a cylinder misfire has occurred. Furthermore, the inventor recognized the need to develop a method for monitoring and detecting EMP fluctuations to determine the occurrence of a misfire.

[0017] DE 10 2006 006 114 A1 discloses a method for detecting misfires in internal combustion engines via the dynamic pressure sensitivity of the lambda probe. DE 102 30 786 A1 discloses a method for detecting misfires, for example, misfires, in internal combustion engines with an exhaust duct arrangement connected to a combustion chamber. Misfires are detected by detecting an exhaust gas temperature and / or an exhaust gas pressure, which is dependent on the degree of combustion in a respective combustion chamber, or a change in the exhaust gas temperature and / or the exhaust gas pressure, at least following an ignition point before the next ignition point, in a lambda probe in the exhaust duct arrangement and evaluating them for a deviation from a normal value. SUMMARY OF THE INVENTION

[0018] It is an object of the present invention to provide an improved system and method for detecting whether an engine cylinder misfire is occurring in an internal combustion engine.

[0019] It is an object of the present invention to provide a method for monitoring and detecting EMP fluctuations in combination with one or more sensed engine characteristics to detect the occurrence of a misfire.

[0020] It is a further object of the invention to provide a system and method for accurately and reliably detecting engine misfire by analyzing changes in EMP fluctuations with respect to in-cylinder pressures and other engine operating conditions to detect whether engine cylinder misfire is occurring.

[0021] It is a further object of the invention to provide one or more processes for determining a cylinder misfire condition of an engine as present or absent with respect to a determined fresh air flow (FAF), engine type, engine data inputs, and / or analytical determinants using the present invention, wherein the one or more processes include an estimated exhaust manifold pressure process (EEMPP) or a centroid projection process (CPP).

[0022] As used herein, the term engine parameters (EP) is intended to represent and include, among other things, the FAF and various other engine parameters and information (hereinafter "engine parameters", "information", and the like) related to engine load, such as fuel quantity, mass charge flow (MCF), etc. For non-stoichiometric engine applications, fuel quantity can be used as a direct substitute for the FAF. The EFAF is intended to represent the estimated fresh air flow. Furthermore, the term estimated engine parameters (EEP) is intended to represent and include, among other things, engine parameters and information related to the estimated engine load, such as estimated fuel quantity, estimated mass charge flow (EMCF), estimated fresh air flow (EFAF), associated thresholds, etc.

[0023] As used herein, a sensed engine characteristic may include any of the engine characteristics, information, or the like measured or otherwise sensed by a sensor during engine operation, including (but not limited to) an EP such as the EMP, a FAF, an engine speed, a MAF, an exhaust gas recirculation (EGR) fuel pressure, an ambient pressure, a turbine speed, a turbine position, and the like.

[0024] The present invention meets these needs and was developed in response to the current state of the art, and in particular in response to the problems and needs of the art that have not yet been fully addressed by currently available technologies. The present invention provides a method, a system, and a computer program product for detecting a misfire condition of an engine cylinder using known approaches.

[0025] The invention is described in the appended set of claims. In one embodiment, the present invention provides a method for detecting engine cylinder misfire in an internal combustion engine by comparing a first engine parameter (FEP) with a first estimated engine parameter (FEEP) for a first cylinder of an engine and determining a first process, wherein the first process is an estimated exhaust manifold pressure process (EEMPP) or a centroid projection process (CPP), and wherein the CPP is based at least in part on an estimated exhaust manifold pressure (EMP).The embodiment, in response to determining the first process, calculates an operating value (OV) with respect to one or more engine characteristic data inputs and a comparative value (CV) associated with a threshold, wherein the OV and the CV are calculated using either the EEMPP or the CPP. Further, the OV and the CV are compared, and a misfire condition is determined for the first cylinder based on the comparison of the OV to the CV. Preferably, in one embodiment, the first process is an estimated exhaust manifold pressure (EEMPP) process or a center of gravity projection (CPP) process, for which, if the FEP is less than the FEEP, the initiated process is the EEMPP. Therefore, in this embodiment, the FEP represents a first load variable (FLV), and the FEEP represents a first estimated load variable (FELV).Furthermore, it is preferred that the one or more data inputs include at least one of the following: EMP, engine speed, mass air flow (MAF), EGR pressure, ambient pressure, turbine speed, and turbine position. For the avoidance of doubt, the term FEP shall be understood including (but not limited to) the description provided above with respect to the EP (e.g., an FAF, an MCF, an engine load, a fuel quantity, an engine characteristic, a flow rate, etc.), and the term FEEP shall be understood including (but not limited to) the description above with respect to the EEP (e.g., an estimated engine characteristic, an estimated engine load, an EFAF, an EMCF, an estimated fuel quantity, an estimated flow rate, or another estimated value associated with the FEP).

[0026] In another embodiment, the present invention provides a method for detecting an engine cylinder misfire in an internal combustion engine by comparing a FAF with an EFAF for a first cylinder of the engine and initiating a first process.

[0027] In another embodiment, the present invention provides a system for detecting a misfire condition of an engine cylinder in an internal combustion engine. The system includes: at least one pressure sensor operatively coupled to the engine to detect an exhaust manifold pressure (EMP); at least one data sensor operatively coupled to the engine to detect one or more engine parameters; and a control system for the engine having an exhaust outlet. The embodiment further includes the control system having a plurality of actuator controllers in communication with the at least one pressure sensor and the at least one data sensor;a data processor of the control system, the data processor configured to receive data measured from the at least one pressure sensor and the at least one data sensor, determine a first process (wherein the first process is an estimated exhaust manifold pressure process (EEMPP) or a centroid projection process (CPP), and where the CPP is based at least in part on an estimated exhaust manifold pressure (EMP)), use the first process to calculate an operating value (OV) based on the received data and a comparison value (CV) associated with a threshold, compare the OV and the CV, and detect a misfire condition for the cylinder based on the comparison of the OV to the CV;

[0028] In another embodiment, the present invention provides a computer program product stored on a non-transient computer-usable medium for detecting a misfire condition of an internal combustion engine having one or more cylinders, comprising a computer-readable program that causes a computer to control the execution of an application within a memory control device in operative communication with an engine. The computer-readable program, when executed by a computer, provides for determining one or more data input conditions of engine characteristics of the engine, comparing a first load variable (FLV) with a first estimated load variable (FELV) for a first cylinder of the engine,Determining a first process for use based on comparing the FLV to the FELV (wherein the first process is an estimated exhaust manifold pressure process (EEMPP) or a centroid projection process (CPP), and where the CPP is based at least in part on an estimated exhaust manifold pressure (EMP)); using the determined first process to calculate an operating value (OV) based on the one or more engine characteristic data inputs and a comparison value (CV) associated with a threshold; comparing the OV to the CV; and detecting a misfire condition for the first cylinder based on the comparison of the FLV to the FELV. Preferably, the present invention is adapted for use in, on, or with a vehicle, an engine (diesel, gasoline, natural gas, hybrid engine, etc.), a diagnostic tool,a computer system or similar.,

[0029] In yet another embodiment, a diesel engine configured to detect an engine cylinder misfire is provided.In the embodiment, the engine includes logic for: comparing a first load variable (FLV) to a first estimated load variable (FELV) for one or more cylinders of the engine, determining a first process to use (wherein the first process is an estimated exhaust manifold pressure (EEMPP) process or a center of gravity projection (CPP) process, where the CPP is based at least in part on an estimated exhaust manifold pressure (EMP)) in response to determining the first process, applying the first process, calculating an operating value (OV) based on one or more engine characteristic data inputs and a comparison value (CV) associated with a threshold, comparing the OV to the CV, and detecting a misfire condition for the one or more cylinders of the diesel engine based on the comparison of the OV to the CV.

[0030] Further embodiments, forms, objects, features, advantages, aspects and benefits of the present application will become apparent from the detailed description and drawings contained herein. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a block diagram illustration of one form of the control system 100 of the present invention according to one embodiment of the present invention, Fig. 2A is a block diagram of the method of the present invention according to one or more embodiments thereof, Fig. 2B is a block diagram of an implementation of a method of the present invention according to one or more embodiments thereof, Fig. 3 is a block diagram of the additional processing of a method of the present invention including the step of an estimated exhaust manifold pressure process (EEMPP) according to one or more embodiments thereof, Fig. 4 is a block diagram of the additional processing of a method of the present invention including the step of a centroid projection process (CPP) according to one or more embodiments thereof, Fig. Figure 5 illustrates representative results when applying the present invention according to one or more embodiments thereof, and Fig. Figure 6 is an overall view of a spark ignition type internal combustion engine with a control device in communication with the spark ignition system, the injector, and an EGR configuration, which can operate with the present invention, Fig. 7 is a flowchart of a slow diagnostic method according to one embodiment, Fig. Figure 8 illustrates the results of the magnitude-frequency relationship according to one aspect of the present invention, Fig. 9 illustrates a flowchart of the method of a preferred embodiment in which one or more sensed engine characteristics are used to detect an engine cylinder misfire in an internal combustion engine having at least one cylinder, Fig. Figure 10 shows a plot of EMP, notch filter output, notch filter residue, and misfire effect. DETAILED DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS

[0031] The following description is presented to enable those of ordinary skill in the art to practice the invention and is intended in the context of a patent application and its requirements. Various modifications of the preferred embodiments and the general principles and features described herein will be readily apparent to those skilled in the art. Thus, the present invention is not intended to be limited to the embodiments shown, but is to be accorded the widest scope consistent with the principles and features described herein.

[0032] To promote an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings, and specific language will be used to describe the same. It should be understood, however, that no limitation of the scope of the invention is intended, and such variations, modifications, and further applications of the principles of the present invention as illustrated herein are contemplated as would normally occur to those skilled in the art to which the invention pertains.

[0033] The present invention provides a method, a control system, and a computer program product, which provide a control method for detecting a misfire condition of an engine cylinder using known methods applicable to engines. The present invention contemplates, in one or more embodiments, the application of multiple actuation techniques, alone or in combination, sequentially or simultaneously, individually or in parallel, and sometimes predetermined, as well as as a result of actual or predicted events.

[0034] Fig. 1 is a block diagram illustration of one form of the control system 100 of the present invention according to one embodiment of the present invention. In Fig. 1, an internal combustion engine 110 is in communication with an engine control module (ECM) 120, which provides control information for the operation of the engine. The ECM 120 is in communication with a control system processor 130, which is in communication with a controller 140 for controlling the operation of the present invention, although other configurations are also contemplated by the present invention. A system memory 150 is associated with the system processor 130 and can store information related to the operation and activities of the present invention. A sensor or sensors for measuring and receiving information from measured sources associated with engine operation are provided at 160 and are in communication with the system processor 130 and the controller 140.

[0035] In a preferred embodiment, actuators, not shown, may also be associated with the sensors and controlled by the controller for enabling / disabling measurement and collecting data inputs of the engine operation associated with the sensors. Example sensors 160 may include an airflow sensor 170, an exhaust manifold pressure sensor 180, and a data sensor or sensors 190 associated with other engine operating modes and characteristics (such as, but not limited to, exhaust manifold pressure (EMP), engine speed, fuel quantity, mass air flow (MAF), exhaust gas recirculation (EGR) pressure, ambient pressure, turbine speed and position, etc.). In a preferred embodiment, a misfire condition detected with the present invention may be communicated to the ECM 120, memory 150, and / or a data output 195 (e.g., data interface, display, printer, etc.).In a further preferred embodiment, an A / D converter may also be connected to each sensor to convert the acquired data into a suitable data format for processing by the present invention.

[0036] Fig. 2A is a block diagram of the method 200 of the present invention according to one or more embodiments thereof. In Fig. 2A, the process starts at 201 for a particular cylinder of the engine. At 202, a first engine parameter (FEP) is measured using one or more data inputs from sensed data or other collected data related to the engine, engine operation, or engine operating characteristics. According to one example, the FEP represents a first load variable (FLV). The FLV is an indicator of the load encountered by a stoic engine. Similarly, at 202, a first estimated engine parameter (FEEP) related to the engine type or engine operating conditions is calculated. In the above example, the FEEP represents a first estimated load variable (FLV). At 203, the FEP and the FEEP are compared, and a first process of the present invention is initiated at 204 in response to the comparison at 203.

[0037] Once initiated, the process then calculates an operating value (OV) and a comparison value (CV) associated with the particular first process initiated at 205, which is further detailed below. At 206, the OV and CV are compared to determine a particular misfire condition result, which is then determined at 207. The misfire condition is preferably output at 208, and the process of the present invention may continue for another cylinder of the engine at 209.

[0038] It is understood that the process of Fig. 2A has many applications in a variety of engine types in operation. As applied herein, it is understood that the present invention may utilize a number of different characteristics for the FEP and the FEEP. In the above example, the FEP and the FEEP represent the engine load (FLV and FELV). According to further embodiments, the FEP may be an engine characteristic, an engine load, a fuel quantity, a mass flow rate (MCF), a fresh air flow (FAF), and / or a flow rate, and the FEEP may be an estimated engine characteristic, an estimated engine load, an estimated fuel quantity, an estimated mass flow rate (EMCF), an estimated fresh air flow (EFAF), and / or an estimated flow rate associated with the FEP.

[0039] Fig. 2B is a block diagram of the implementation of the method 299 of the present invention according to one or more embodiments thereof. In Fig. 2B, the process represents an implementation of the FEP as a fresh air flow (FAF) and the FEEP as an estimated fresh air flow (EFAF). The process of Fig. 2B starts at 210 for a particular cylinder of the engine. At 220, the FAF is measured using one or more data inputs from sensed data or other collected data related to the engine, engine operation, or engine operating characteristics. Fresh air flow is an indicator of load in a stoic engine; this may be replaced by fuel quantity or other such load indicators. Similarly, at 220, the EFAF is calculated related to the engine type or engine operating conditions. At 230, the FAF and EFAF are compared, and a first process of the present invention is initiated at 240 in response to the comparison at 230. Once initiated, the process then calculates an operating value (OV) and a comparison value (CV) associated with the particular first process initiated at 250, which will be further detailed below.At 260, the OV and CV are compared to determine a detected misfire condition result, which is then determined at 270. The misfire condition is preferably output at 280, and the process of the present invention may continue for another cylinder of the engine at 290.

[0040] Fig. 3 is a block diagram 300 of the additional processing of a method of the present invention including the step of an estimated exhaust manifold pressure (EEMPP) process according to one or more embodiments thereof. Fig. 3, the process of the present invention starts at 301 for a particular cylinder of the engine, where it is determined whether the FLV is greater than the FELV generated at 305 (in this example, the FEP and FEEP represent the FLV and FELV, respectively). It should be understood that the present invention provides various methods for determining the FELV, measuring the FLV, and comparing the two, as stated herein. If the FLV is not greater than the FELV, the CPP of the present invention is selected at 306 (discussed elsewhere herein). If the FLV is greater than the FELV, the EEMPP process of the present invention is selected at 310.

[0041] At 310, the EEMPP process includes estimating the EMP (ESTEMP) at 315. Such estimation may be performed through estimation calculations, including: applying algorithms, looking up tables related to the engine and / or operating mode, and similar other characteristics of a specific engine and / or its operation. In further preferred embodiments, the ESTEMP may be determined as a function of time via an exponential moving average. The estimation may also be performed by applying a higher-order model that incorporates the change in exhaust manifold pressure over each iteration. In addition, a physics-based model or an empirical model may also be used. Some such examples may include: ESTEMP=f(EMP(t−1),…EMP(t−k),diag(t−1),…diag(t−k;or: EWMA model P˜e(t)={αPe(t−1)+(1−α)P˜e(t−1)if d(t−1)=0βPe(t−1)+(1−β)P˜e(t−1)if d(t−1)=1α>>β Second-order model P˜e(t)=Pe(t−1)+ΔPe(t−1)+(1−α1)(P˜e(t−1)−Pe(t−1)) +(1−α2)(ΔPe(t−1)−ΔPe(t−1)),if d(t−1)=0 P˜e(t)=Pe(t−1)+ΔPe(t−1)+(1−α1)(P˜e(t−1)−Pe(t−1)) +ΔPe(mcf(t),vgt(t)),if d(t−1)=1 ΔP e (mcf(t), vgt(t)) is a calibratable / empirical model parameterized by charge flow and VGT position from misfire cylinder data. Physics-based model P˜e(t)=Pe(t−1)+(1−α)(P˜e(t−1)−Pe(t−1))+d(Pe),if d(t−1)=0 P˜e(t)=Pe(t−1)+(1−α)(P˜e(t−1)−Pe(t−1))+d(Pe)+ΔPe(mcf(t),vgt(t)) when d(t−1)=1 d(P e ) / d(mcf) = K(vgt) is a calibratable / empirical model parameterized by charge flow and VGT.

[0042] ΔP e (mcf(t), vgt(t)) is a calibratable / empirical model parameterized by charge flow and VGT position obtained from misfire cylinder data.

[0043] At 320, the residue threshold (also used as CV) is determined, preferably, for example, as a function of turbocharger position (e.g., variable geometry turbocharger (VGT) position), although other characteristic functions and operating conditions may also be used.

[0044] At 325, the residue (also known as OV) is determined as the difference between the EMP and the ESTEMP. A comparison of the residue and the residue threshold is then performed at 330. If at 335 the residue is greater than the residue threshold (i.e., OV > CV), a misfire flag is set at 341. If at 335 the residue is not greater than the residue threshold (i.e., OV > CV), no misfire flag is set at 342. At 350, the process proceeds to evaluate a next cylinder of the engine.

[0045] Fig. 4 is a block diagram 400 of the additional processing of a method of the present invention, including the step of a centroid projection process (CPP) according to one or more embodiments thereof. In Fig. 4, the process of the present invention starts at 401 for a particular cylinder of the engine, determining whether the FLV is greater than the FELV generated at 405 (in this example, the FEP and FEEP are represented as the FLV and the FELV, respectively). It should be understood that the present invention provides various methods for determining the FELV, measuring the FLV, and comparing the two, as provided herein.

[0046] If the FLV is greater than the FELV, the present invention selects the EEMPP process at 406. If the FLV is not greater than the FELV, the present invention selects the CPP process at 410.

[0047] At 410, the CPP process includes calculating the center of gravity coordinates at 315. Such estimation may be performed through estimation calculations, including the application of algorithms, table lookups related to the engine and / or operating mode, and similar other characteristics of the specific engine and / or its operation. It should be understood that the CPP is often, though not necessarily, performed when conditions result in low flow conditions. When implemented, the CPP uses the center of gravity of the EMP signal to detect the occurrence of a misfire. For the present invention, the center of gravity captures the position and magnitude of the energy EMP signal for each cylinder in operation.

[0048] At 420, the present invention then projects the coordinates (i.e., OV) onto a dividing line predetermined from test data. It is understood that any statistical pattern classification technique, such as linear discriminatory analysis, Fisher discriminatory analysis, and support vector machines, etc., may be used to establish this dividing line within the scope of the present invention. Preferred projection: Centroid_y-A*Centroid_x-B, where A and B are coefficients of the dividing line. An example projection of the coordinates onto a dividing line for a representative test result is shown at 421.

[0049] At 425, the CV is determined, and in one or more preferred embodiments, the CV is set equal to zero. At 430, the process determines whether the projected center of gravity coordinates are greater than or equal to the CV (i.e., OV > or = CV). At 441, where it is determined that the projected center of gravity coordinates are greater than or equal to CV, a "no misfire" determination is made, and no flag is set to indicate a misfire. At 442, where it is determined that the projected center of gravity coordinates are neither greater than nor equal to the CV, a "one misfire" determination is made, and a flag is set to indicate a misfire.

[0050] At 450, the process moves on to evaluate the next cylinder of the engine.

[0051] Fig. Figure 5 illustrates representative results when applying the present invention according to one or more embodiments thereof. In Fig. 5, the EMP-cylinder relationship is illustrated at 510, showing data using the present invention representing peaks in the residue signal, thereby identifying the misfiring cylinders. Similarly, at 520, the probability density functions of the residues are evaluated using the method of the present invention, showing the separation between the data for the normal and misfiring cylinders under various conditions.

[0052] Fig. Figure 6 shows an overall view of a spark-ignition type internal combustion engine 600 having a controller 650 in communication with the spark igniter 610, an injector 620, and an EGR configuration 630 that can operate with the present invention. Fig. 6 shows 601 a crankcase with cylinder and piston, 602 a cylinder block, in which a combustion chamber is also provided in the upper part. Also in Fig. 6, a spark plug is arranged at 606 in the center of a surface of the combustion chamber 607 via an igniter at 681 in communication with the control device 650. Furthermore, an air intake port is arranged at 651, an exhaust port at 631, and a NOx sensor at 681, via 682 in communication with the control device.

[0053] Also provided at the top of block 602 are intake ports, but not shown in the diagram. These ports are connected by intake branch pipes, within which injectors are arranged for injecting fuel toward the corresponding intake ports. An exemplary representation of an injector is shown at 620, although the present invention may also utilize a high-pressure rail configuration and is thus not otherwise limited. Furthermore, the injectors may also be arranged inside the combustion chambers within the scope of the present invention, rather than being attached to the intake branch pipes.

[0054] An exhaust port 631 is connected through an exhaust manifold, within which an AFR sensor 621 is typically located in communication with the controller 650. The exhaust manifold and the intake manifolds are connected by the EGR passage (not shown), which is connected via an EGR valve 630 for exhaust gas recirculation ("EGR gas") in communication with the controller 550 at 541. An exhaust valve is also provided at 524.

[0055] Typically, an EGR control valve 630 is disposed within the EGR passage, with an EGR cooler disposed around the EGR passage for cooling the EGR gas flowing through the interior of the EGR passage. As used herein, the EGR passage, EGR control valve, and EGR cooler are collectively referred to as the "EGR mechanism." The load on the engine is determined from inputs from 661, e.g., a load sensor, and this is in communication with controller 650.

[0056] An example of an EGR configuration suitable for use with the present invention is discussed in U.S. patent application US 2010 / 0 147 272 A1, entitled "Exhaust Gas Recirculation Cooler Coolant Plumbing Configuration," the teachings of which are incorporated herein by reference. In U.S. patent application US 2010 / 0 147 272 A1, the cooling system may include a heat exchanger, a pump connected to the heat exchanger, an EGR cooler connected to the pump, a first valve connected to the EGR cooler, and the heat exchanger. The configuration uses a valve to maximize the rate of coolant flow through the entire system when the valve is in the open position and also to warm up an engine when the valve is in a closed position.

[0057] Inputs from engine operation determine engine speed and are connected to controller 650 at 691. Similarly, exhaust gas temperature may be monitored by a sensor and communicated to controller 650 at 692, as may crank angle (crank angle sensor not shown), which is also connected to controller 650.

[0058] The controller 650 (similar to the controller 140) is preferably an electronic control unit consisting of a digital computer, which may, for example, comprise a programmable computer product of the present invention and have components connected and interconnected, for example, by a backbone circuit or other bidirectional bus such as a ROM (Non-Writable Memory), a RAM (Random Access Memory), a CPU (microprocessor), an input channel, and an output channel. The present invention may also be a circuit, application, logic, or other electronic means within a controller such as 650, or may be separate and connected to the controller 650.In certain embodiments, the controller 650 forms part of a processing subsystem, including one or more computing devices having storage, processing, and interconnect hardware. The controller 650 may be a single device or a distributed device, and the functions of the controller may be performed by hardware and / or as computer instructions on a non-transient, computer-readable storage medium. In certain embodiments, the controller 650 includes one or more modules structured to functionally perform the operations of the controller 650.

[0059] The misfire detection method of the present invention 690 receives and communicates data with the engine control device 650 (i.e., ECM, controller, data communication port, etc.) and processes the data in accordance with the steps of the present invention to detect whether a misfire is present for a cylinder of the engine. It should be understood that there are many variations for connecting and communicating engine data in the present invention, and that the diagrams of the figures herein are not intended to be limited in this regard.

[0060] In operation, a detected knock output signal 682 from the NOx sensor 681 is typically input via a corresponding analog-to-digital (A / D) converter. In operation, various sensors described hereinbefore may be placed at various operating points within and along the engine to determine various EPs such as FAF, EMP, VGT position, engine speed, MAF, EGR pressure, ambient pressure, turbine speed, turbine position, and other engine characteristics and operating parameters included as data input for use by and with the present invention (including "engine characteristic data input" and / or "sensed data input").

[0061] Another embodiment of the present invention includes a slow diagnostic method that looks for continuous misfire in one or more cylinders. In one embodiment, a slow monitoring method uses an average model of the EMP to detect continuous misfire. Fig. 7 is a flowchart of a slow diagnostic method according to one embodiment. First, in step 702, a filtered value of the EMP is determined. Then, in step 704, the filtered value of the EMP is compared to an estimated EMP. Finally, in step 706, a misfire in one or more cylinders is detected based on a comparison. The slow monitor of the present invention (i.e., slow monitor filter) is employed on a filtered EMP to provide only cycle-by-cycle estimates. This slow monitor filter approach can also be a diagnostic approach used to determine a continuous misfire in one or more cylinders and as a confirmatory check. The slow diagnostic looks for continuous misfire in one or more cylinders. It considers a filtered value of the EMP and compares it to an estimated EMP.The estimated EMP is determined by calibration between the EMP, the fresh air flow, the VGT position, and the turbo speed. An averaging model that estimates the pressure ratio based on the inversion of the turbo map can also be used with the present invention. In a preferred embodiment, the slow monitor filter model uses the charge flow, the turbo speed, and the VGT position to calculate the turbo pressure ratio from the turbo maps and then estimates the EMP by either measuring or estimating the turbo output pressure.

[0062] Likewise, in one or more preferred embodiments of the present invention, the control system comprises a plurality of actuator controllers in communication with the one or more data input sensors. Additionally, a data processor of the present invention is preferably connected to the at least one data input sensor and is capable of receiving or transmitting an input of sensed data.

[0063] In another preferred embodiment for the EEMPP process, the residue threshold is the CV, and the residue is the OV; and for the CPP, the CV is a value of projected center-of-gravity coordinates, and the CV is less than one. Furthermore, in another aspect, if the residue is greater than the residue threshold, a misfire condition may be determined to be present by the present invention. Furthermore, the CV may have any value, positive or negative, including zero, particularly for the CPP.

[0064] In another embodiment of the present invention, a method for monitoring and detecting EMP fluctuations in combination with one or more sensed engine characteristics is provided to detect the occurrence of a misfire.

[0065] In a preferred embodiment, the present invention uses the frequency content of the EMP signal to detect a misfire.

[0066] An EMP fluctuation can arise in several ways, including by opening a cylinder exhaust valve and introducing combusted gases into the exhaust. Since exhaust valve opening is a periodically based process, it is understood that the EMP is associated with a strong periodic component and is generally unaffected by engine disturbances in the present invention. Therefore, when one or more cylinders misfire, the energy in the associated frequency range is disrupted. The present invention conveniently determines the misfire information in terms of the associated frequencies, this information being generally representative of the operating conditions.

[0067] In a preferred embodiment, the present invention uses a filter to extract the relevant frequencies and determine the magnitude of the filtered component. If, during operation, a misfire causes a disturbance in the filter output, the disturbance can be used to detect the misfire according to the present invention. In one or more preferred embodiments, a notch filter or a bandpass filter can be used to extract the relevant frequency component.

[0068] To detect a misfire in a cylinder of an engine using the present invention, the magnitude of the EMP at the engine rotational frequency is extracted. To detect two consecutive cylinder misfires, the associated frequency may conveniently be determined as twice the rotational speed, etc. A notch filter is designed for use with the present invention and is applied when the residue of the filter output is used in the misfire detection sequence.

[0069] In a preferred embodiment, the filters in the crank area can preferably be independent of the speed and depend only on the number of samples per revolution. As an example, the response of the notch filter when applying the present invention in Fig. 8 is shown at 800, with the results of the magnitude-frequency relationships shown at 810 and phase-frequency relationships shown at 820.

[0070] Fig. 9 shows a flowchart 900 of the method of a preferred embodiment of the present invention in which one or more sensed engine characteristics are used to detect an engine cylinder misfire in an internal combustion engine having at least one cylinder. In Fig. 9, an EMP is measured or extracted at 910, after which the notch filter is employed at 920 for a notch filter response, and the filter output is used in the misfire detection sequence at 930. At 930, the output of the notch filter and the measured EMP are used, and after initiating the calculation at 935, the calculation of an error term for each cycle is initiated at 940. According to an exemplary embodiment, the error term comprises a root mean square (RMS) value for each extracted EMP value. In this embodiment, a threshold is determined at 945, and the result of the RMS calculation is compared to the predetermined threshold at 950 to determine if a misfire has occurred. If the RMS calculation is greater than or equal to the threshold, a flag is set at 960 indicating a misfire.If the RMS calculation is less than the threshold, a flag is set at 970 to indicate that no misfire occurred.

[0071] Fig. Figure 10 shows a plot 1000 of the EMP at 1010, the notch filter output at 1030, the notch filter residue at 1050, and the effect of misfire at 1070.

[0072] Conveniently, the method of the present invention eliminates the need to adjust each vehicle's monitor for a specific engine, as sensitivity to vehicle dynamics is significantly reduced. Those skilled in the art will appreciate that numerous variations to the above steps may be applied or modified while remaining within the scope of the present invention.

[0073] As used herein, various engines may be employed with the present invention, and preferably those having spark ignition, fuel injection, and EGR capability. However, the invention is not limited in this manner; rather, it is within the spirit of the present invention that additional or alternative activation methods are within the present scope and may be employed or implemented with engines configured to support such associated activation. It is further contemplated that engines that ideally benefit from various embodiments hereunder will include control devices at subsystems and components that are in operative communication with one another to support commands that include activation and are results of the operation of the present invention.

[0074] Any theory, mechanism of operation, evidence, or finding recited herein is intended to further enhance the understanding of the present invention and is not intended to make the present invention dependent in any way on any such theory, mechanism of operation, evidence, or finding. It is to be understood that the use of the words prefer, preferably, or preferred in the above description indicates that while the feature so described may be more desirable, it may nevertheless not be essential, and that embodiments lacking such feature may be considered within the scope of the invention, which scope is defined by the following claims.

[0075] Furthermore, according to one example, the present invention may be developed to meet the CARB OBD II requirements established by the California Regulations Board, or the like. According to various other embodiments, the present disclosure may be applicable to and implemented in various other on-board diagnostic systems, such as OBD I and high-performance on-board diagnostic systems.

[0076] The present invention can be used in a variety of engines and engine types, including, for example, an internal combustion engine, a diesel engine, a hybrid engine system, and a battery-powered engine.

[0077] Preferably, the system described herein detects an engine misfire while a vehicle is operating. By efficiently and accurately detecting misfires as described above, the present invention provides a system and method for reducing engine wear in a cost-effective manner.

[0078] Although the invention has been described with reference to the aforementioned embodiments, it should be understood by those skilled in the art that the invention may be practiced otherwise than as specifically described herein without departing from the spirit and scope of the invention. Therefore, it is intended that the spirit and scope of the invention be limited only by the appended claims.

[0079] Furthermore, the description herein, including the modules, emphasizes the structural independence of the aspects of, for example, the controller 650 and the controller 140 and illustrates a grouping of work processes and responsibilities of the controllers. It is contemplated that other groupings that perform similar general work processes are within the scope of the present application. The modules may be implemented as hardware and / or computer instructions on a non-transient, computer-readable storage medium, and the modules may be distributed across various hardware or computer-based components. Further specific descriptions of particular embodiments of controller operations are included in the section relating to Fig. 1 and Fig.6. Example and non-limiting module implementation elements include sensors that provide a value determined herein, sensors that provide a value that is a precursor to a value determined herein, datalink and / or network hardware including interconnect chips, oscillating crystals, communication links, cables, twisted pairs, coaxial wiring, shielded wiring, transmitters, receivers and / or transceivers, logic circuits, hardwired logic circuits, reconfigurable logic circuits in a particular non-transient state configured according to the module specification, wherein each actuator comprises at least one of an electric, hydraulic or pneumatic actuator, a coil, an operational amplifier, analog control elements (springs, filters, integrators, adders, dividers, gain elements), and / or digital control elements.

[0080] The system and method for detecting engine cylinder misfire in internal combustion engines have obvious industrial applicability, including that useful in an environment where a user desires constant monitoring of the average peak exhaust pressure during a combustion cycle and the operating characteristics of an engine to determine whether engine operation is abnormal or outside of specified tolerances, such as in stationary power sources and vehicle engines.

Claims

[1] A method for detecting an engine cylinder misfire in an internal combustion engine having at least one cylinder, comprising: Comparing a first load variable (FLV) with a first estimated load variable (FELV) for a first cylinder of the engine; determining a first process, wherein the first process is an estimated exhaust manifold pressure process (EEMPP) or a centroid projection process (CPP), and wherein the CPP is based at least in part on an estimated exhaust manifold pressure (EMP); in response to determining the first process, calculating an operating value (OV) with respect to one or more engine characteristic data inputs and a comparative value (CV) associated with a threshold, wherein the OV and the CV are calculated using either the EEMPP or the CPP; Comparison of the OV with the CV, and Detection of a misfire condition for the first cylinder based on comparing the OV with the CV. [2] The method of claim 1, further comprising detecting a misfire condition when the OV is greater than the CV. [3] The method of claim 1, wherein when the FLV is greater than the FELV, the first process used is the EEMPP, whereby the FLV is an engine characteristic, an engine load, a fuel quantity, a mass charge flow (MCF), a fresh air flow (FAF), and / or a flow rate, and the FELV is an estimated engine characteristic, an estimated engine load, an estimated fuel quantity, an estimated mass charge flow (EMCF), an estimated fresh air flow (EFAF), and / or an estimated flow rate associated with the FLV. [4] The method of claim 3, wherein if the FLV is less than the FELV, the first process used is the CPP. [5] The method of claim 4, wherein the one or more data inputs include at least one of: exhaust manifold pressure (EMP), engine speed, fuel quantity, mass air flow (MAF), exhaust gas recirculation (EGR) pressure, ambient pressure, turbine speed, and turbine position. [6] The method of claim 5, further comprising the step of repeating the method for one or more additional cylinders of the engine, wherein the engine is an internal combustion engine, a diesel engine, a hybrid engine system, and / or a battery-powered engine. [7] The method of claim 5, wherein the EEMPP further comprises: a) estimating an EMP for the first cylinder (ESTEMP), b) determining a residue threshold with respect to one or more data inputs, and c) calculating a residue as the difference between a measured EMP and the ESTEMP. [8] The method of claim 7, wherein the one or more data inputs is the turbine actuator or turbocharger position. [9] The method of claim 7, wherein the residue threshold is the CV and the residue is the OV. [10] The method of claim 9, wherein the misfire condition is determined to be present when the residue is greater than the residue threshold. [11] The method of claim 10, wherein a misfire condition is determined as a detected misfire when the residue is greater than the residue threshold. [12] The method of claim 9, wherein the misfire condition is determined not to exist if the residue is not greater than the residue threshold. [13] The method of claim 9, wherein a misfire condition is determined to be detected when the OV is greater than the CV. [14] The method of claim 8, wherein the EEMPP further comprises estimating the EMP (ESTEMP) using an autoregressive-based, physically-based, or exponential moving average. [15] The method of claim 8, wherein the CPP further comprises: a) calculating the center of gravity coordinates associated with the measured EMP and b) projecting the associated center of gravity coordinates onto a dividing line. [16] The method of claim 15, wherein projecting the associated centroid coordinates onto a dividing line further comprises analyzing using one or more pattern classification techniques including at least one of linear discriminant analysis techniques and support vector machines. [17] The method of claim 16, wherein the OV is a value of projected center of gravity coordinates, and the CV is less than one. [18] The method of claim 17, wherein the CV is zero. [19] The method of claim 18, wherein if the OV is greater than the CV, a misfire condition is determined to be no misfire. [20] The method of claim 18, wherein if the value of projected center of gravity coordinates is greater than or equal to zero, a misfire condition is determined not to exist. [21] The method of claim 18, wherein if the residue is greater than the residue threshold, a misfire condition is determined to be present. [22] The method of claim 18, further comprising the step of repeating said method for a second cylinder of the engine. [23] The method of claim 7, wherein the measured EMP corresponds to an EMP signal. [24] The method of claim 1, wherein the CPP performs a determination of one or more center of gravity coordinates and magnitude of the energy EMP signal. [25] A system for identifying a misfire condition of an engine cylinder in an internal combustion engine, comprising: at least one pressure sensor operatively connected to the engine to detect an exhaust manifold pressure (EMP); at least one data sensor operatively connected to the engine to detect one or more engine characteristics of the engine; and a control system for the engine having an exhaust outlet; the control system comprising a plurality of actuator controllers in communication with the at least one pressure sensor and the at least one data sensor; a data processor of the control system, the data processor of which is configured to: receive data measured by the at least one pressure sensor and the at least one data sensor; determine a first process, wherein the first process is an estimated exhaust manifold pressure process (EEMPP) or a centroid projection process (CPP), and wherein the CPP is based at least in part on an estimated exhaust manifold pressure (EMP); using the first process to calculate an operating value (OV) based on the received data and a comparison value (CV) associated with a threshold; and compares the OV and the CV and to detect a misfire condition for the cylinder based on comparing the OV with the CV. [26] The system of claim 25, wherein the engine further comprises an exhaust gas recirculation (EGR) system. [27] The system of claim 25, wherein the received data is an engine characteristic, an engine load, a fuel quantity, a mass flow rate (MCF), a fresh air flow (FAF) and / or a flow rate, and the estimated associated data is an estimated engine characteristic, an estimated engine load, an estimated fuel quantity, an estimated mass flow rate (EMCF), an estimated fresh air flow (EFAF) and / or an estimated flow rate associated with the received data. [28] The system of claim 27, wherein if the received data is less than the estimated associated data, the first process used is the EEMPP, and wherein if the received data is not less than the estimated associated data, the first process used is the CPP. [29] The system of claim 28, wherein the EEMPP further comprises: a) estimating an EMP for the first cylinder (ESTEMP), b) determining a residue threshold with respect to one or more data inputs, and c) calculating a residue as the difference between the EMP and the ESTEMP; and wherein the CPP further comprises: a) calculating the center of gravity coordinates associated with the EMP, and b) projecting the associated center of gravity coordinates onto a parting line. [30] The system of claim 29, wherein one or more data inputs for the EEMPP are the turbocharger position. [31] The system of claim 29, wherein for the EEMPP, the lag threshold is the CV, and the lag is the OV; and for the CPP, the CV is a value of projected center of gravity coordinates, and the CV is less than one. [32] The system of claim 27, wherein the one or more data inputs include at least one of the following: EMP, engine speed, mass air flow (MAF), exhaust gas recirculation (EGR) pressure, ambient pressure, turbine speed, and turbine position. [33] The system of claim 32, wherein when the value of projected center of gravity coordinates is greater than or equal to zero, a misfire condition is determined not to exist. [34] The system of claim 32, wherein if the residue is greater than the residue threshold, a misfire is determined to be present. [35] A computer program product stored on a non-transient computer-usable medium for detecting a misfire condition of an internal combustion engine having one or more cylinders, comprising a computer-readable program for causing a computer to control the execution of an application within a memory control device in operative communication with an engine; the computer-readable program, when executed by a computer, for: Determination of one or more data input conditions of engine characteristics of the engine; Comparing a first load variable (FLV) with a first estimated load variable (FELV) for a first cylinder of the engine; determining a first process for use based on the comparison of the FLV to the FELV, wherein the first process is an estimated exhaust manifold pressure process (EEMPP) or a centroid projection process (CPP), and wherein the CPP is based at least in part on an estimated exhaust manifold pressure (EMP); Using the determined first process to calculate an operating value (OV) based on the one or more engine characteristic data inputs and a comparison value (CV) associated with a threshold value; Comparison of the OV and the CV and Detect a misfire condition for the first cylinder based on comparing the FLV to the FELV. [36] The computer program product of claim 35, wherein the engine includes one or more of EGR, direct injection, and spark retard events. [37] The computer program product of claim 35, wherein the one or more data inputs include at least one of: exhaust manifold pressure (EMP), engine speed, mass air flow (MAF), exhaust gas recirculation (EGR) pressure, ambient pressure, turbine speed, and turbine position [38] The computer program product of claim 35, wherein if the FLV is less than the FELV, the first process used is the EEMPP, and wherein if the FLV is not less than the FELV, the first process used is the CPP, whereby the FLV is an engine characteristic, an engine load, a fuel quantity, a mass flow rate (MCF), a fresh air flow (FAF), and / or a flow rate, and the FELV is an estimated engine characteristic, an estimated engine load, an estimated fuel quantity, an estimated mass flow rate (EMCF), an estimated fresh air flow (EFAF), and / or an estimated flow rate associated with the FLV. [39] The computer program product of claim 38, wherein the EEMPP further comprises: a) estimating an EMP for the first cylinder (ESTEMP), b) determining a lag threshold with respect to one or more data inputs, and c) calculating a lag as the difference between the EMP and the ESTEMP; and wherein the CPP further comprises: a) calculating the center of gravity coordinates associated with the EMP, and b) projecting the associated center of gravity coordinates onto a parting line. [40] The computer program product of claim 39, wherein for the EEMPP, the backlog threshold is the CV, and the backlog is the OV; and for the CPP, the CV is a value of the projected center of gravity coordinates, and the CV is less than one. [41] The computer program product of claim 40, wherein if the value of projected center of gravity coordinates is greater than or equal to zero, a misfire condition is determined not to exist. [42] The computer program product of claim 41, wherein if the residue is greater than the residue threshold, a misfire condition is determined to be present. [43] A computer program product according to claim 35, configured for use in a vehicle having an engine which is one or more of a diesel engine, a natural gas engine, a hybrid engine, a battery-powered engine, or configured as a diagnostic tool suitable for the engine. [44] The computer program product of claim 35, further comprising a slow monitor filter applying a mean value model or a frequency-based model. [45] Diesel engine configured to detect engine cylinder misfire, with logic for: Comparison of a first load variable (FLV) with a first estimated load variable (FELV) for one or more cylinders of the engine, Determining a first process for use which is an estimated exhaust manifold pressure process (EEMPP) or a center of gravity projection process (CPP), wherein the CPP is based at least in part on an estimated exhaust manifold pressure (EMP), in response to determining the first process, applying the first process, calculating an operating value (OV) based on one or more engine characteristic data inputs and a comparison value (CV) associated with a threshold value; Comparison of the OV with the CV and Detection of a misfire condition for one or more cylinders of the diesel engine based on the comparison of the OV with the CV. [46] The engine of claim 45, wherein when the FLV is less than the FELV, the applied first process is the EEMPP, and wherein when the FLV is not less than the FELV, the logic applied as the first process is the CPP, whereby the FLV is one or more of an engine characteristic, an engine load, a fuel quantity, a mass charge flow (MCF), a fresh air flow (FAF), and / or a flow rate, and the FELV is one or more of an estimated engine characteristic, an estimated engine load, an estimated fuel quantity, an estimated mass charge flow (EMCF), an estimated fresh air flow (EFAF), and / or an estimated flow rate associated with the FLV condition in which no misfire is detected. [47] The engine of claim 46, wherein when the OV is greater than the CV, a misfire condition is determined to be no misfire.

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