Fuel Rail Pressure Sensor Diagnostics via DFCO and Shutdown
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Solution Overview
Problem
Inaccurate fuel rail pressure sensors in internal combustion engines lead to increased emissions due to excess or insufficient fuel injection, and existing diagnostic techniques often cause adverse effects on vehicle operation and fuel system durability by frequently commanding extreme pressure changes.
Innovation Solution
A method involving two diagnostic routines executed by the engine controller to detect faults in fuel rail pressure sensors, one during deceleration fuel cutoff events and another during engine shutdown, which actively manage fuel rail pressure to accurately assess sensor accuracy without damaging the system, using pressure differences to identify sensor faults.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing diagnostic techniques frequently command extreme pressure changes to test the fuel rail pressure sensor, then the sensor accuracy can be assessed, but the fuel system durability deteriorates
Solution Approach 1:
The diagnostic routine is executed preliminarily during normal engine operation before actual failure occurs, using the upcoming DFCO event as the trigger. This allows sensor accuracy to be tested under normal operating conditions rather than through extreme pressure changes that would damage the system.
Solution Approach 2:
The fuel rail pressure sensor diagnostic is performed using the engine's own operational cycles (DFCO events) rather than requiring external testing equipment or extreme test conditions. The system uses its normal fuel injection and pressure regulation processes to automatically test the sensor accuracy.
2Object-generated harmful factors
If the fuel rail pressure sensor is inaccurate, then emissions increase due to excess or insufficient fuel injection, but the device complexity increases if continuous monitoring is implemented
Solution Approach 1:
Instead of continuous monitoring, the diagnostic routine is executed periodically at upcoming DFCO events. This periodic execution reduces the complexity of the monitoring system while still providing regular assessment of sensor accuracy to prevent emissions problems.
Solution Approach 2:
The system uses feedback from the fuel rail pressure sensor readings during the diagnostic routine to determine sensor accuracy. This feedback mechanism allows the controller to identify when the sensor is inaccurate and take appropriate action without requiring complex continuous monitoring infrastructure.
Data Source
AI summary
A first computer-implemented diagnostic method can run in response to an imminent deceleration fuel cutoff (DFCO) event. A second computer-implemented diagnostic method can run on engine shutdown. Both diagnostic methods involve controlling fuel injectors and a fuel pump to make the fuel rail pressure change from a desired minimum to a desired maximum. Measurements from the fuel rail pressure sensor at these endpoints can then be used to detect a fault of the fuel rail pressure sensor. One or both diagnostic methods can be implemented.