13 - Cylinder Contribution Tests

13. Cylinder Contribution Tests





Purpose:
To test individual cylinders and injectors to determine if all are contributing equally to engine performance. This is a test performed after a standard KOER test is performed.

Recommended Procedure:
If the base engine condition meets specifications, the injector may not be functioning correctly and will need replacement. The solenoid and wiring should have been checked in earlier tests. Verify KOEO Injector electrical Self Test passed.

NOTE: The A/C must be OFF and engine oil temperature above 76.6°C (170°F) to run this test.

This test will determine if all cylinders are contributing equally to engine performance. The PCM will test the cylinders in order. This test consists of two portions. First, the 8-cylinder test checks for a non-contributing cylinder; then, the 4-cylinder test detects a weak cylinder. The 4-cylinder portion of the test will never run if a fault is detected on the 8-cylinder portion of the test. The engine will give off smoke and rpm will vary for each test although you will not hear an rpm difference between good and bad cylinders during the test. A fault must be present at the time of testing for the KOER Cylinder Contribution Self Test to detect a fault. If a fault is detected, a 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.

Possible Causes:
Failing this test could indicate mechanical engine problems such as:
- broken compression rings
- leaking or bent valves
- bent push rods
- bent connecting rods
- damaged rocker arms
- faulty injector assembly

Tools Required:
New Generation Star Tester 007-00500 or equivalent