Checking Engine Mechanical Systems

NOTE: If coming to this test from oxygen sensor (O2S) test and rich or lean condition is not corrected after checking items listed below, replace Powertrain Control Module (PCM). Perform TEST VER-2 .

At this point in diagnostic test procedure, all engine control systems have been determined to be operating as designed and not causing a driveability problem. Following additional items should be checked as possible causes:

Check if any Technical Service Bulletins (TSBs) apply to vehicle.
Check engine compression.
Check for exhaust system restriction.
Check camshaft and crankshaft sprockets.
Check valve timing.
Check torque converter stall speed.
Check engine vacuum. It must be at least 13 in. Hg in Neutral.
Check for fuel contamination.
Ensure PCV system is functioning properly.
Ensure injector control circuit is connected to correct fuel injector and injector is not plugged or restricted.
Check power booster for internal vacuum leak.