Recommended Procedure

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A/C must be off and engine oil temperature above 68°F (21°C) to run Cylinder Contribution Self-Test. This test will determine if all cylinders are contributing equally to engine performance. The PCM will test all eight cylinders continuously during the test; there is no change in engine speed or operation that can be detected by the technician. The test checks for cylinder-to-cylinder decrease in speed and sets a code if the decrease is too high. A fault must be present at the time of testing for the KOER Cylinder Contribution Self-Test to detect a fault, so the engine operating condition at which the idle is worst will produce the best test results. If a fault is detected, a Diagnostic Trouble Code (DTC) will be output on the data link at the end of the test when requested by a scan tool. Only a hard fault code (DTC) will be displayed.

If KOER CYLINDER CONTRIBUTION SELF-TEST under QUICK TEST in SELF-DIAGNOSTICS - 7.3L DIESEL article has been successfully completed previously and no DTCs were present, go to TEST 13: EXHAUST RESTRICTION . If KOER CYLINDER CONTRIBUTION SELF-TEST has not been completed, perform KOER CYLINDER CONTRIBUTION SELF-TEST under QUICK TEST in SELF-DIAGNOSTICS - 7.3L DIESEL article. Only hard fault DTCs will be stored. Service any DTCs that are present. Ensure KOER CYLINDER CONTRIBUTION SELF-TEST passes.