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 TESTS W/CODES articles were performed before diagnosing a symptom. Symptoms available for diagnosis include the following:

• Will Not Start (Cranks Okay)
• Hard Starting (Cranks Okay)
• Engine Surges
• Rough, Unstable Or Incorrect Idle
• Excessive Fast Idle
• Engine Stalls
• Lack of Power, Sluggish or Spongy
• Hesitation, Sag or Stumble
• Engine Backfires
• Poor Fuel Economy
• Detonation/Spark Knock.