NTC-18A Checking the Engine Mechanical Systems

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At this point in the diagnostic test procedure, you have determined that all of the engine electrical systems are operating as designed; therefore, they are not the cause of the driveability problem. The following additional items should be checked as possible mechanical causes of the problem:

NOTE: Always look for any Technical Service Bulletins that may relate to the problem.

1. ENGINE VACUUM - must be at least 13 inches in neutral (see below)

2. ENGINE VALVE TIMING - must be within specifications

3. ENGINE COMPRESSION - must be within specifications

4. CAMSHAFT LOBES - check for abnormal wear

5. CRANK SENSOR PICK-UP - check crankshaft slots for debris/deterioration

6. ENGINE EXHAUST SYSTEM - must be free of any restrictions

7. ENGINE PCV SYSTEM - must flow freely

8. ENGINE DRIVE SPROCKET - must be properly positioned

9. TORQUE CONVERTER STALL SPEED - must be within specifications

10. POWER BRAKE BOOSTER - no internal vacuum leaks

11. FUEL - must be free of contamination

12. FUEL INJECTOR - plugged or restricted injector; control wire not connected to correct injector

NOTE: If you came to this test from the oxygen sensor, and the rich or lean condition is not caused by one of the first items above, replace the powertrain control module and perform TEST VER-2A (Road Test Verification). Verification Test VER-2A - Road Test Verification

NOTE: The readings in the image are only indicators of possible mechanical engine problems.