NOTE: For circuit identification, see WIRING DIAGRAMS article. After each repair procedure has been completed, reconnect all components. Perform TEST VER-2 to ensure system is functioning properly. Ensure no DTCs are present before performing this test.

Prior to performing this test, all engine electrical systems have been determined to be operating as designed and not causing a driveability problem. The following items should be checked as possible causes of a driveability problem:

Check for technical service bulletins relating to driveability problem.
Check engine vacuum. Engine vacuum must be at least 13 in. Hg in with transmission in Neutral.
Check engine valve timing.
Check engine compression.
Check camshaft lobes for abnormal wear.
Check crankshaft sensor pick-up. Check crankshaft slots for debris or deterioration.
Check exhaust system for restrictions.
Ensure PCV system is functioning properly.
Check camshaft and crankshaft sprockets for proper position.
Check torque converter stall speed.
Check power brake booster for internal vacuum leak.
Check fuel for contamination.
Ensure proper injector driver wiring is installed on correct injector. Ensure injector is not plugged or restricted.

When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.

• Brakes feel soft, pull hard to one side, or make grinding noises.

• The engine overheats, stalls repeatedly, or misfires under load.

• You are missing required tools, torque specs, or safe lifting equipment.

• You are not confident in the next step or safety outcome.

Safety Warning

Test NTC-4: Checking Engine Mechanical Systems

Use the Manual With the Right Hardware

When to See a Mechanic

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