KOER Cylinder Contribution Self-Test: Description
KOER CYLINDER CONTRIBUTION SELF-TEST is a functional test of PCM performed on demand with engine running, A/C off and engine oil temperature above 70°F (21°C). This test will determine if all cylinders are contributing equally to engine performance. PCM will test all 8 cylinders continuously during test and there is no change in engine speed or operation that will be detectable by technician. See Fig 1. Test checks for cylinder-to-cylinder changes in engine RPM, and sets a DTC if RPM change is not within a pre-calibrated range. Test also checks for weak injectors or low compression cylinders. A fault must be present at time of testing for KOER CYLINDER CONTRIBUTION SELF-TEST to detect a fault, so engine operating condition at which idle is worst will produce best test results. For automatic transmission vehicles, best results are reached with parking brake set and transmission in Drive. If a fault is detected, a DTC will be output at end of test when requested by a scan tool. Only a hard fault DTC will be displayed.