DRIVEABILITY Test No 24 - Non-Engine Control Related Problems

At this point in driveability testing procedures, all engine control systems have been determined to be operating properly. Therefore, engine control system devices are not the cause of the driveability problem. Check the following items as possible causes of driveability problem:

• Engine vacuum MUST be at least 13 in. Hg in Neutral.
• Valve timing must be set to specifications.
• Engine compression must be within specifications.
• Engine exhaust system must be free of restrictions.
• Engine PCV system must flow freely.
• Ensure engine drive sprockets (camshaft and crankshaft) are properly installed, meshed and timed.
• Torque converter stall speed must be within specifications.
• Power brake booster must not have any internal vacuum leaks.
• Fuel must not be contaminated (high alcohol and water content).
• Crossed fuel injector control wires (wrong wire connected to injector) may cause rough idle.

Any one or more of these conditions can cause a driveability related problem. They must be considered as possible causes.