Symptom Diagnosis

Symptom checks cannot be used properly unless the problem is actually happening while the vehicle is being tested. To reduce diagnostic time, ensure steps in BASIC DIAGNOSTIC PROCEDURES article have been performed before attempting to diagnose 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 has lack of power
• Engine misfires or hesitates
• Afterburn in exhaust system
• Poor fuel mileage
• Detonation or knocking
• Fails emission test