Symptom Diagnosis

Symptom checks cannot be used properly unless problem occurs while vehicle is being tested. To reduce diagnostic time, ensure steps in BASIC TESTING and TESTS W/CODES articles in the ENGINE PERFORMANCE Section were performed before diagnosing a symptom. These symptoms are available for diagnosis.

• Backfire through induction or exhaust.
• Dieseling (run-on).
• Lack of power.
• Spark knock (pinging).
• Stalls/quits.
• Stumble/hesitation during acceleration.
• Misses/surges.
• Idle is fast/slow return to idle.
• Idle is rough.
• Engine speeds up.
• Cranks normally/no start.
• Cranks normally/slow to start.
• Poor fuel economy.
• Exhaust smoke/odor.
• Fuel odor/leaks.
• Fails emission test.