Pinpoint Test AO: Injector Control Pressure Too High: Introduction: Detection/Management
An open or shorted to ground control circuit can be detected by an on demand output circuit check performed during the KOEO test. When the starter is engaged and the engine fails to start, the IPR command increases toward its maximum until the engine starts. The normal range for the IPR at idle is between 16-24%. An above 24% range indicates high effort or higher commanded ICP to achieve idle. A below 16% indicates low effort to achieve idle.
The PCM is capable of detecting whether the desired injection control pressure is equal to the measured injection control pressure while the engine is running. If the measured injection control pressure does not reasonably compare to the desired injection control pressure, the PCM ignores the measured ICP sensor signal and attempts to control the engine with the desired value. (If the problem is in the sensor circuit, this strategy causes little performance deterioration. If the problem is in the control circuit, engine performance will probably still be unsatisfactory).
An injection control pressure step test, in which the PCM commands and then measures calibrated pressures, is performed during the KOER test.