PDI volumetric efficiency paste

Abstract

A port and direct fuel injection (PDI) fuel delivery system for a vehicle having an engine configured to selectively operate between a port fuel injection (PFI) mode, a gasoline direct injection (GDI) mode, and a PDI mode, the system including a PFI system including a plurality of PFI injectors, and a GDI system including a plurality of GDI injectors. The PFI and GDI systems are configured to provide various fuel mass injection split ratios to the engine based on particular engine operating conditions. The controller is programmed to identify a known first long term fuel correction (LTFT) for the first split ratio, identify a known second LTFT for the second split ratio, generate a linear equation based on the known first and second LTFTs, and determine an unknown third LTFT for the third split ratio using the linear equation in order to reduce fueling errors and emissions.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Application Serial No. 17 / 881,071, filed on August 4, 2022. The disclosure of this application is incorporated herein by reference in its entirety. Technical Field

[0003] The present application relates generally to internal combustion engines and, more particularly, to systems and methods for predicting long-term fuel trim for engines having port and direct fuel injection systems. Background Art

[0004] Internal combustion engines have traditionally used port fuel injection (PFI) fuel delivery technology. PFI engines mix fuel and air at the intake port and then draw the mixture into the engine cylinder for combustion. This mixing is performed to optimize combustion and improve engine performance. Recently, gasoline direct injection (GDI) fuel delivery technology has been introduced to improve fuel economy. GDI engines draw air into the cylinder during the intake stroke and inject fuel directly into the cylinder to mix with the air during the intake or compression stroke. This mixing may provide improved fuel economy and engine performance under various load conditions. However, both PFI and GDI engines have their own unique advantages and disadvantages compared to each other.

[0005] To take advantage of the benefits of both systems, some engines include both port and direct fuel injection (PDI) fuel delivery systems. Conventional fuel adaptation strategies have been utilized to minimize fueling errors. However, when using a PDI system, the errors learned when operating in one fueling mode (PFI or GDI) may not be nearly as accurate as the errors in the other mode. This can result in long term fuel correction inaccuracies which can negatively impact emissions, especially when attempting to run scavenges. Therefore, while such systems may work well for their intended purpose, it is desirable to provide continued improvements in related areas. Summary of the invention

[0006] According to an exemplary aspect of the present invention, a port and direct fuel injection (PDI) fuel delivery system for a vehicle having an engine configured to selectively operate between a port fuel injection (PFI) mode, a gasoline direct injection (GDI) mode, and a PDI mode is provided. In an exemplary embodiment, the PDI fuel delivery system includes: a PFI system including a plurality of PFI injectors configured to supply fuel to the engine during the PFI mode, and a GDI system including a plurality of GDI injectors configured to supply fuel to the engine during the GDI mode. The PFI system and the GDI system are configured to provide various fuel mass injection split ratios to the engine based on specific engine operating conditions, the split ratio being a ratio of fuel mass injection of the PFI injectors to fuel mass injection of the GDI injectors. The controller is programmed to identify a known first long term fuel correction (LTFT) for a first split ratio, identify a known second LTFT for a second split ratio, generate a linear equation based on the known first LTFT and the second LTFT, and determine an unknown third LTFT for a third split ratio using the linear equation, thereby helping to reduce fueling errors and emissions.

[0007] In addition to the above, the system may include one or more of the following features: wherein the linear equation is LTFT = (slope * split ratio) + offset, wherein the slope and offset are determined based on the known first LTFT and second LTFT and the first split ratio and the second split ratio; wherein the controller includes or is configured to reference a table of various split ratios for a PDI fuel delivery system indexing a specific engine operating condition; wherein the controller is configured to paste the determined third LTFT into the table as a known third LTFT at a third split ratio; wherein the controller is configured to determine all unknown LTFTs in the table and paste the determined LTFTs into the corresponding split ratio data cells in the table.

[0008] In addition to the above, the system may include one or more of the following features: wherein the table includes a plurality of regions, each region corresponding to a specific split ratio; wherein the known first LTFT is a learned LTFT established when a persistent error from a first short-term fuel correction (STFT) for a first split ratio is transferred to the first LTFT so that the first STFT is restored to a nominal value; and an EVAP system configured to store and subsequently dispose of fuel vapor emissions, wherein the controller is configured to operate the EVAP system based on a determined third LTFT.

[0009] According to another exemplary aspect of the present invention, a method for controlling a port and direct fuel injection (PDI) fuel delivery system for an engine having a port fuel injection (PFI) system and a gasoline direct injection (GDI) system, the engine being configured to selectively operate between a PFI mode, a GDI mode, and a PDI mode. In an exemplary embodiment, the method includes: identifying, by a vehicle controller, a known first long-term fuel correction (LTFT) for a first split ratio; identifying, by the vehicle controller, a known second LTFT for a second split ratio; generating, by the vehicle controller, a linear equation based on the known first LTFT and the second LTFT, and determining, by the vehicle controller, an unknown third LTFT for a third split ratio using the linear equation, thereby facilitating reduction of fueling errors and emissions.

[0010] In addition to the above, the method may also include one or more of the following features: wherein the linear equation is LTFT = (slope * split ratio) + offset, wherein the slope and offset are determined based on the known first LTFT and second LTFT and the first split ratio and the second split ratio; a table of various split ratios of the PDI fuel delivery system for a specific engine operating condition is referenced by the controller; the determined third LTFT is pasted into the table as a known third LTFT at a third split ratio by the controller; all unknown LTFTs in the table are determined by the controller, and the determined LTFT is pasted into the corresponding split ratio data cell in the table; wherein the table includes multiple areas, each area corresponding to a specific split ratio; wherein the known first LTFT is a learned LTFT, which is established when a persistent error from a first short-term fuel correction (STFT) of the first split ratio is transferred to the first LTFT so that the first STFT is restored to a nominal value; and wherein the engine includes an EVAP system configured to store and subsequently dispose of fuel vapor emissions, wherein the vehicle controller is configured to operate the EVAP system based on the determined third LTFT.

[0011] Further areas of applicability of the teachings of the present disclosure will become apparent from the detailed description, claims, and drawings provided below, wherein like reference numerals refer to like features in the several views of the drawings. It should be understood that the detailed description, including the disclosed embodiments and the figure references therein, are merely exemplary in nature and are used for illustration purposes only and are not intended to limit the scope of the present disclosure, its application, or use. Therefore, variations that do not depart from the gist of the present disclosure are intended to be within the scope of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 is a schematic diagram of an engine and fuel delivery system according to the principles of the present disclosure;

[0013] Figure 2 is an example table that indexes fuel split ratios for engine speed / load operating conditions into data cells in accordance with the principles of the present disclosure;

[0014] Figure 3 is an example graph showing volumetric efficiency correction versus split ratio to be affixed according to the principles of the present disclosure; and

[0015] Figure 4 The invention is shown in accordance with the principle of the present disclosure. Figure 1 An example control strategy approach for long term fuel correction prediction of a fuel delivery system is shown in FIG. DETAILED DESCRIPTION

[0016] The present application is generally directed to control systems and strategies for engines equipped with port and direct fuel injection (PDI) systems, the engine being configured to selectively operate between port fuel injection (PFI) mode, gasoline direct injection (GDI) mode, or a combination of the two (PDI mode). The fuel delivery system changes the operating mode to take advantage of the advantages of both the PFI system and the GDI system, for example, reducing emissions and / or improving fuel economy. The advantages of the GDI system include charge cooling / knock mitigation, combustion stability (EGR), ignition / spark retard authority, combustion duration reduction, and multiple injection events. The advantages of the PFI system include fuel / air vaporization time (cold), reduced intake / valve deposits, reduced particulates, reduced oil dilution risk, and quieter operation.

[0017] In an example embodiment, a control strategy is referred to as PDI volumetric efficiency (VE) "pasting" within an engine control unit (ECU) that allows for faster "learning" (e.g., building) of long-term fuel correction (LTFT) data cells to reduce emissions for PDI-equipped vehicles. The fuel adaptation strategy utilizes LTFT and short-term fuel correction (STFT) to keep fueling errors to a minimum. The LTFT is arranged into data cells indexed by engine speed and load. In one example, the short-term fuel correction (STFT) is an instantaneous correction to the amount of fuel delivered to the engine based on errors indicated by one or more O2 sensors. The long-term fuel correction (LTFT) is a cumulative correction to the amount of fuel delivered to the engine. The LTFT may also be referred to as a volumetric efficiency correction, which describes a correction to an airflow estimation model. The LTFT and STFT work together to ensure that the error in the amount of fuel delivered to the engine is minimized. The sum of the LTFT and STFT represents the total fuel correction, or the total system richness or leanness.

[0018] During operation, there are engine speeds / loads where the engine will operate using only the PFI system, only the GDI system, or a combination of the PFI and GDI systems (PDI mode). When operating in PDI mode, the system operates at various split ratios, which are the ratios of GDI to PFI fueling (or vice versa). As described in more detail herein, these split ratios are indexed in a table by a data cell ID, and the data cell is populated and updated when the volumetric efficiency (or LTFT) has been "learned" or established for that particular data cell.

[0019] Due to the way the vehicle is driven, some unit IDs will be updated or "learned" faster than others. This is because a unit is only updated when the vehicle is operating in the conditions corresponding to that unit. Once a unit has been updated, the system marks it as "learned". However, while some units will update and "learn" quickly, other units may not be updated at all. In some cases, it may be desirable to update or "learn" all data units, but this is not possible during normal driving. Therefore, the control strategy described in this article uses information from learned units to paste values ​​into unlearned units.

[0020] Fueling errors can occur in either the PFI or GDI fuel systems of a PDI-equipped vehicle. Therefore, information from both systems must be utilized when determining what fuel correction value to paste into the unlearned cells. It is assumed that the fuel correction error is caused only by the PFI and GDI fuel systems, and the resulting error can be modeled based on the contribution of each system to the total fueling. The pasting strategy for PDI-equipped vehicles described in this article utilizes a linear equation where the LTFT to be pasted is a function of the split ratio.

[0021] To create a linear equation, two points are needed to calculate the slope and offset. Therefore, the fuel correction from two different split ratios with the learned cell is used. This leads to the equation LTFT = (slope * split ratio) + offset. From here, the value to be pasted into the unlearned data cell can be obtained by entering the split ratio corresponding to the unlearned data cell.

[0022] First reference Figure 1 , an example internal combustion engine for a vehicle is shown and generally identified by reference numeral 10. The internal combustion engine 10 generally includes an air induction system 12, a fuel delivery system 14, and an exhaust system 16 having one or more catalytic converters 18 and an O2 sensor 19.

[0023] The engine 10 also includes a cylinder head and block 20 that defines one or more cylinders 22, each housing a reciprocating piston (not shown). Air and fuel are supplied to combustion chambers 24 of the cylinders 22 via the air induction system 12 and the fuel delivery system 14, respectively. The air / fuel mixture is ignited in the combustion chamber 24, and the resulting combustion gases are directed from the combustion chamber 24 to the exhaust system 16.

[0024] The air induction system 12 generally includes an air filter 26, a throttle control valve 28, and an intake manifold 30. Air enters the vehicle through an intake port 32 and is filtered in the air filter 26 before being delivered to intake ports 34 of the cylinders 22 for combustion therein.

[0025] In the exemplary embodiment, the fuel delivery system 14 generally includes a low-pressure fuel pump 36, a port fuel injection (PFI) fuel system 38, and a gasoline direct injection (GDI) fuel system 40. The PFI fuel system 38 includes a PFI fuel pressure rail 42 and a plurality of PFI injectors 60, and the GDI fuel system 40 includes a GDI fuel pressure rail 44, a plurality of GDI injectors 62, a first deactivation GDI fuel pump assembly 46, and a second deactivation GDI fuel pump assembly 48. In the exemplary embodiment, the engine 10 includes a three-function fuel delivery system 14, which is configured to be controlled by an engine control unit (ECU) 50 to selectively operate between a PFI mode, a GDI mode, or a combination of the two (PDI mode), as described in more detail herein. Generally speaking, the engine operates in a PFI mode at low engine load conditions or when the boost motion is low, in a GDI mode at high engine load conditions or when the boost motion is high, and in a PDI mode at other speed / load conditions.

[0026] The low pressure fuel pump 36 is disposed within the fuel tank 52 and is configured to supply fuel from the fuel tank 52 to a main fuel delivery line 54. As shown, the main fuel delivery line 54 supplies fuel to a PFI fuel delivery line 56 and a GDI fuel delivery line 58. The PFI fuel delivery line 56 is fluidly coupled to the PFI fuel pressure rail 42 to supply fuel to the PFI injectors 60. In the exemplary embodiment, the PFI injectors 60 are configured to supply fuel to the intake ports 34 where the fuel is mixed with air from the air induction system 12 and then supplied to the combustion chambers 24.

[0027] GDI fuel delivery line 58 is fluidly coupled to GDI fuel pressure rail 44 to supply fuel to GDI injectors 62. In the exemplary embodiment, GDI injectors 62 are configured to supply fuel directly to cylinders 22 where the fuel mixes with air from air induction system 12 and combusts. Figure 1As shown, the GDI fuel delivery line 58 is divided into a first GDI fuel supply line 64 and a second GDI fuel supply line 66. Each of the first and second fuel supply lines 64, 66 is fluidly coupled to the GDI fuel pressure rail 44 so that an increased fuel supply can be provided to the GDI injectors 62 when high output is required to meet peak engine power or torque requirements.

[0028] In one example, the first GDI fuel supply line 64 supplies a portion (e.g., three) of the GDI injectors 62, and the second GDI fuel supply line 66 supplies another portion (e.g., the remaining three) of the GDI injectors 62. However, in embodiments having only a single deactivated GDI pump assembly 46, 48, all of the GDI injectors 62 are supplied by that assembly 46 or 48. The GDI fuel pump assemblies 46, 48 are disposed on the GDI fuel supply lines 64, 66 and are configured to be controlled by the ECU 50 (or other controller) to selectively operate between an activated mode and a deactivated mode.

[0029] The engine 10 also includes an evaporative emission control (EVAP) system 68, which is configured to store and subsequently dispose of fuel vapor emissions to prevent the fuel vapor from escaping into the atmosphere. The EVAP system 68 is in fluid communication with the fuel tank 52 and the air induction system 12. The EVAP system 68 is designed to collect vapors generated within the engine fuel system and then deliver the vapors to the combustion chamber 24 through the engine intake manifold 30 to be burned as part of the aggregate fuel-air charge. When the pressure within the fuel tank 52 increases due to evaporation, the fuel vapors are transferred and stored in a carbon canister (not shown). Subsequently, when engine operating conditions are favorable, the ECU 50 opens the valve and the vacuum from the intake manifold 30 draws a purge flow of stored hydrocarbons from the canister to the combustion chamber 24 of the engine. Thereafter, the carbon canister is regenerated with the newly formed fuel vapors and the cycle can continue.

[0030] Continue to refer Figure 1 , the engine 10 equipped with PFI, GDI and PDI operating capabilities is configured to operate in various modes to selectively improve vehicle emissions, fuel economy and / or engine power output. Since each of the PFI, GDI and PDI fuel systems has a different amount of air and fuel error, the ECU 50 adopts a control strategy to treat the fuel error as a function of the split ratio. This provides a more accurate prediction of what the unlearned data unit should learn. This is especially important for the purge strategy of the EVAP system 68, because if the engine is operated under the condition that the data unit is not learned, the system will stop the purge operation.

[0031] As described above, the EVAP system 68 will only be activated when the data cell ID is considered to be learned. This is because, once the purge is turned on, the LTFT is not updated. Therefore, it is up to the STFT to keep the fuel-air ratio close to its target. If the LTFT is not learned or is not accurately pasted, the STFT will not be able to maintain the fuel-air ratio at its target. Therefore, by pasting long-term adaptation into the unlearned cell (thereby making the data cell "learned"), the EVAP system 68 can continue to purge stored hydrocarbons. Therefore, the pasting control strategy described herein is configured to prevent the situation where the purge must be turned off in order to further update the LTFT, thereby reducing emissions.

[0032] In general, the air-fuel adaptation strategy uses the LTFT and STFT to maintain a desired air-fuel ratio. These corrections are calculated based on the air-fuel ratio of the exhaust gas measured by the O2 sensor 19 in the exhaust system 16. If the air-fuel ratio indicates that too little fuel is being injected, the correction will increase the amount of fuel to be injected. If the air-fuel ratio indicates that too much fuel is being injected, the correction will decrease the amount of fuel to be injected.

[0033] The long term correction and short term correction work together to compensate for the total error in the system. The STFT is a correction that is constantly updated based on the measured air / fuel ratio. This correction reacts immediately to errors in the measured air / fuel ratio to ensure that it always matches the desired air / fuel ratio. The purpose of the LTFT is to save or "learn" the error in the system and be able to proactively apply it and prevent any additional errors in the air / fuel ratio. If the right conditions have been met, the LTFT will begin to adapt and update using the STFT. Any long term error that can be seen in the STFT is essentially transferred to the LTFT. This will restore the STFT to closer to nominal.

[0034] If the process of transferring the persistent error from the STFT to the LTFT has been completed and the STFT has returned to nominal, then the LTFT can be said to have been "learned". This means that the ECU 50 now has a good estimate of the error in the fuel system and can actively compensate for it to ensure that the air / fuel ratio remains close to its desired value without having to react to the error. When the LTFT is learned, the STFT returns to nominal and can be used to identify and adapt to errors that may be inherent in other fueling sources, such as the purge system.

[0035] Reference now Figure 2, the sticking control strategy will be described in more detail. In the example embodiment, the sticking control strategy advantageously accounts for PFI and GDI fuel system errors and applies them to the unlearned cells based on the split ratios of these particular data cells. In the example shown, the ECU 50 generates a table 100 consisting of individual data cells 102 representing the fuel system split ratios for various engine speed / load operating conditions in PFI mode, GDI mode, and PDI mode.

[0036] Each data cell 102 represents engine operation at a predetermined speed and load. Thus, each cell 102 is defined by calibrable load and RPM breakpoints (e.g., cell boundaries). This allows the calibrator to adjust the way the cell IDs are selected. Based on a particular speed and load, the engine will be fueled at a predetermined split ratio. Data cells 102 with the same split ratio can be grouped into split ratio regions, such as Figure 2 100. As the system learns the LTFT for a particular cell, it populates that cell with the learned LTFT, e.g., as shown in “before pasting” table 100. Once the system has learned a predetermined number of LTFT cells in at least two split ratio regions, the system can learn any unlearned cells through a pasting operation (“after pasting” table 100), as described in more detail herein.

[0037] In the example shown, table 100 includes twenty-six individual data cells 102 numbered 0-25. Data cells 0, 24, and 25 represent engine operating regions in PFI-only mode (100% PFI, split ratio = 0). In this example, data cell 24 corresponds to an idle drive reverse (Drive-Reverse) engine operating condition, and data cell 25 corresponds to an idle park neutral (Park-Neutral) engine operating condition. Data cells 1, 4, and 5 represent engine operating regions in a first PDI mode (75% PFI, split ratio = 0.25). Data cells 2, 6, and 8-10 represent engine operating regions in a second PDI mode (50% PFI-GDI, split ratio = 0.5). Data cells 3, 7, and 11-15 represent engine operating regions in a third PDI mode (25% PFI, split ratio = 0.75). Data cells 16-23 represent the engine operating region in GDI only mode (100% GDI, split ratio = 1.0).

[0038] During driving, the learned LTFT is used to fill the learned data cells, which can also be expressed as volumetric efficiency (VE). This is shown in Figure 2100 in the "before pasting" table 100 in FIG. As previously described, a data cell is considered "learned" when the persistent error from the STFT is transferred to the LTFT so that the STFT returns to a nominal value. In an example embodiment, the control strategy will only paste after the fuel correction has been learned for at least two different split ratios or split ratio regions. Once this occurs, a linear equation is determined for the purpose of modeling the fuel correction error as a function of the split ratio. The resulting linear equation is determined as:

[0039] LTFT = (Slope * Split Ratio) + Offset From here, a linear equation is used to calculate the value to be pasted into the unlearned data cell based on the split ratio, ensuring that fueling errors from the PFI and GDI systems are accounted for. This is shown in Figure 2 In the "after pasting" table 100.

[0040] Now refer to Figure 3 , an example PDI VE pasting strategy is described and illustrated by plotting a graph 200 of split ratio and VE correction to be pasted. In this example, LTFT (or VE) is learned in one or more cells in, for example, only the PFI region (e.g., Figure 2 200 ). Similarly, the LTFT is learned in one or more cells in another split ratio region (e.g., the 50-50 split ratio region in PDI mode). Next, for each split ratio region, the average LTFT is taken for all learned LTFT cells. For example, the determined average LTFT for the data cells in the PFI region (e.g., data cells 0, 23, 24) is 0.17 ("LTFT1"), and the determined average LTFT for the data cells in the 50-50 split region (e.g., data cells 2, 6, and 8-10) is 0.20 ("LTFT2"). Using the following information, the ECU 50 is able to determine the slope and offset of the LTFT linear equation, as shown in graph 200.

[0041] LTFT = (slope * split ratio) + offset

[0042] LTFT1 = 0.17, split ratio 1 = 0

[0043] LTFT2 = 0.20, split ratio 2 = 0.5

[0044] Slope = 0.06 and Offset = 0.17

[0045] Once the slope and offset are determined based on the learned data unit, the predicted or estimated LTFT can be pasted into the unlearned unit by inputting the corresponding split ratio and the calculated slope / offset of the predicted or estimated LTFT into the linear equation. Figure 3As shown, LTFT3 with a split ratio of 0.25 is equal to 0.185; LTFT4 with a split ratio of 0.75 is equal to 0.215; and LTFT5 with a split ratio of 1.0 is equal to 0.23. Figure 2 As shown in the "after paste" table of , the system then (i) pastes LTFT3 into the data cells corresponding to the 0.25 split ratio region (e.g., cells 1, 4, 5); (ii) pastes LTFT4 into the data cells in the 0.75 split ratio region (e.g., cells 3, 7, 11-15); and (iii) pastes LTFT5 into the data cells in the 1.0 split ratio region (e.g., cells 16-23). ​​Now that all data cells have been "learned", the system can ensure that certain operations (e.g., clearing) are not blocked because the cells are not learned.

[0046] Reference now Figure 4 , a flow chart of an example PDI volumetric efficiency sticking control strategy method 400 according to the principles of the present disclosure is shown. At 402, the ECU 50 generates and / or populates a table that indexes the fuel system split ratio to a correction unit or data unit. Through operation in PFI, GDI and / or PDI mode, each data unit "learns" its LTFT and is populated. At step 404, the ECU 50 determines whether the number of learned data units in a given split ratio area is greater than a predetermined threshold. If not, then at step 406, the ECU 50 determines that the split ratio for the area has not been learned and proceeds to step 410. If yes, then at step 408, the ECU 50 determines that the LTFT for a particular split ratio area has been learned and proceeds to step 410.

[0047] In step 410, the ECU 50 determines whether the number of learned split ratio regions is greater than two. If not, control returns to the start. If yes, based on the learned data unit, the ECU 50 determines LTFT1, LTFT2, split ratio 1, and split ratio 2 in step 412 (see, for example, Figure 3 ). It will be appreciated that the ECU 50 may determine additional LTFTs and split ratios (eg, LTFTn and split ratio n). In step 414, the ECU 50 uses the data determined in step 412 to calculate the slope and offset of the linear equation LTFT=(slope*split ratio)+offset.

[0048] In step 416, the ECU 50 calculates the LTFT for all data cells in the table using the equation LTFT=(slope*divider ratio)+offset. In step 418, the ECU 50 pastes the calculated LTFT values ​​into the appropriate data cells. Control then ends in step 420 and may return to step 404 for another loop if necessary.

[0049] Systems and methods for a fuel delivery system for an internal combustion engine are described herein. The engine and fuel delivery system are configured to selectively operate between a PFI mode, a GDI mode, and a PDI mode. The system includes a PDI volumetric efficiency sticking control strategy within the ECU that is configured to populate unlearned LTFT data cells in a table that indexes the split ratio operating conditions of the PDI system. The strategy utilizes the LTFTs from two different split ratios and the learned data cells to create a linear equation. The split ratio from the unlearned cell is then input into the linear equation to determine the predicted / estimated LTFT value to be stuck into the unlearned cell, thereby making the engine run smoother and reducing emissions.

[0050] It should be understood that the term "controller" as used herein refers to any suitable control device or a group of multiple control devices configured to perform at least a portion of the technology of the present application. Non-limiting examples include an application-specific integrated circuit (ASIC), one or more processors, and a non-transitory memory having instructions stored therein, which, when executed by one or more processors, cause the controller to perform a set of operations corresponding to at least a portion of the technology of the present application. The one or more processors may be a single processor or two or more processors operating in a parallel or distributed architecture.

[0051] It should be understood that the mixing and matching of features, elements and / or functions between various examples may be expressly contemplated herein so that those skilled in the art can understand from the present teachings that features, elements and / or functions of one example may be incorporated into another example as desired, unless otherwise specified above.

Claims

1. A port and direct fuel injection (PDI) fuel delivery system for a vehicle having an engine configured to selectively operate between a port fuel injection (PFI) mode, a gasoline direct injection (GDI) mode, and a PDI mode, the system comprising: a PFI system comprising a plurality of PFI injectors configured to supply fuel to the engine during the PFI mode; a GDI system comprising a plurality of GDI injectors configured to supply fuel to the engine during the GDI mode; wherein the PFI system and the GDI system are configured to provide various fuel mass injection split ratios to the engine based on specific engine operating conditions, the split ratio being a ratio of fuel mass injection of the PFI injector to fuel mass injection of the GDI injector; and A controller configured to: identifying a known first long term fuel correction (LTFT) for a first split ratio; identifying a known second LTFT for a second split ratio; generating a linear equation based on the known first LTFT and the known second LTFT; and The unknown third LTFT for a third split ratio is determined using the linear equation, thereby facilitating reduction of fueling errors and emissions.

2. The PDI fuel delivery system of claim 1, wherein the linear equation is LTFT = (slope * split ratio) + offset, The slope and the offset are determined according to the known first LTFT and the known second LTFT as well as the first split ratio and the second split ratio. 3 . The PDI fuel delivery system of claim 1 , wherein the controller includes or is configured to reference a table indexing various split ratios of the PDI fuel delivery system for the particular engine operating condition.

4. The PDI fuel delivery system of claim 3, wherein the controller is configured to paste the determined third LTFT into the table as a known third LTFT at the third split ratio.

5. The PDI fuel delivery system of claim 3, wherein the controller is configured to determine all unknown LTFTs in the table and paste the determined LTFTs into corresponding split ratio data cells in the table.

6. The PDI fuel delivery system of claim 3, wherein the table includes a plurality of regions, each region corresponding to a specific split ratio.

7. A PDI fuel delivery system according to claim 1, wherein the known first LTFT is a learned LTFT that is established when a persistent error from a first short-term fuel correction (STFT) for the first split ratio is transferred to the first LTFT so that the first STFT is restored to a nominal value. 8 . The PDI fuel delivery system of claim 1 , further comprising an EVAP system configured to store and subsequently dispose of fuel vapor emissions, wherein the controller is configured to operate the EVAP system based on the determined third LTFT.

9. A method of controlling a port and direct fuel injection (PDI) fuel delivery system for an engine, the engine having a port fuel injection (PFI) system and a gasoline direct injection (GDI) system, the engine being configured to selectively operate between a PFI mode, a GDI mode, and a PDI mode, the method comprising: identifying, by a vehicle controller, a known first long term fuel correction (LTFT) for the first split ratio; identifying, by the vehicle controller, a known second LTFT for a second split ratio; generating, by the vehicle controller, a linear equation based on the known first LTFT and the known second LTFT; as well as An unknown third LTFT for a third split ratio is determined by the vehicle controller using the linear equation, thereby facilitating reducing fueling errors and emissions.

10. The method of claim 9, wherein the linear equation is LTFT=(slope*dividing ratio)+offset, The slope and the offset are determined according to the known first LTFT and the known second LTFT as well as the first split ratio and the second split ratio.

11. The method according to claim 9, further comprising: A table indexing various split ratios of the PDI fuel delivery system for the particular engine operating condition is referenced by the controller.

12. The method according to claim 11, further comprising: The determined third LTFT is pasted into the table by the controller as a known third LTFT at the third split ratio.

13. The method according to claim 11, further comprising: All unknown LTFTs in the table are determined by the controller, and the determined LTFTs are pasted into corresponding split ratio data cells in the table.

14. The method of claim 11, wherein the table includes a plurality of regions, each region corresponding to a specific split ratio.

15. The method of claim 9, wherein the known first LTFT is a learned LTFT established when a persistent error from a first short term fuel correction (STFT) for the first split ratio is transferred to the first LTFT to restore the first STFT to a nominal value. 16 . The method of claim 9 , wherein the engine includes an EVAP system configured to store and subsequently dispose of fuel vapor emissions, wherein the vehicle controller is configured to operate the EVAP system based on the determined third LTFT.

Images