Symptom Diagnosis

Symptom checks cannot be used properly unless the problem occurs while the vehicle is being tested. To reduce diagnostic time, ensure steps in BASIC TESTING and G - TESTS W/ CODES articles were performed before diagnosing a symptom. Symptoms available for diagnosis include the following:

• Will not start (cranks okay)
• Difficult start (cranks okay)
• Engine surges
• Rough or unstable idle
• Excessive fast idle
• Engine stalls
• Engine lacks power
• Engine misfires or hesitates
• Afterburn in exhaust system
• Poor fuel mileage
• Detonation or knocking
• Fails emission test