Dr-34A: Performing No Fault Code Mechanical Test
At this point in the driveability test procedure, you have determined that all of the engine control systems are operating properly. The engine control systems are NOT the cause of the driveability problem.
The following items should be checked as possible mechanical causes of the problem:
- ENGINE VACUUM must be at least 13 in. Hg in Neutral.
- ENGINE VALVE TIMING must be within specification.
- ENGINE COMPRESSION must be within specification.
- EXHAUST SYSTEM must be free of restrictions.
- PCV SYSTEM must allow crankcase gases to flow freely.
- ENGINE CAMSHAFT & CRANKSHAFT SPROCKETS must be in good mechanical condition.
- POWER BRAKE BOOSTER must NOT have an internal vacuum leak.
- TORQUE CONVERTER STALL SPEED must be within specifications.
- FUEL CONTAMINATION: Fuel should NOT have a high alcohol or water content.
- FUEL INJECTOR(S) must NOT be plugged or restricted. Ensure that wiring harness is connected to correct injector.
NOTE:
If you were directed to this test by an oxygen sensor problem, and the rich or lean condition is NOT caused by one of the items above, replace the engine controller.