Circuit/System Testing

WARNING: This page is about a different car, the 2017 GMC Acadia. However, it is still accessible from the selected car via links, so may be relevant.

Verify none of the conditions listed below exist:
- Damage, carbon tracking, or fluid intrusion of the spark plug boots and/or spark plugs
- Vacuum hose splits, kinks, and incorrect connections
- Engine vacuum leaks
- Crankcase ventilation system for vacuum leaks
- Fuel pressure that is too low or too high. Refer to Fuel System Diagnosis .
- Contaminated fuel. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .
- Exhaust system restrictions
  - If a condition exists
    Repair or replace as necessary.
  - If no conditions exist

NOTE:

An erratic or weak spark is considered a no spark condition.

Ignition OFF, remove the appropriate T8 Ignition Coil and connect the EL 26792 to the spark plug boot, engine Cranking.
Verify the spark output.
- If no output or the output is weak
  Refer to Electronic Ignition System Diagnosis .
- If the output is good
Ignition OFF.
Verify the conditions listed below. Refer to Ignition System Specifications .
- The correct spark plug type
- The correct spark plug gap
- The correct spark plug torque
- If a condition exists
  Repair or replace as necessary.
- If no conditions exist
Exchange the suspect spark plug with another cylinder that is operating correctly.
Engine Running.
Verify the scan tool Cylinder 1-6 Current Misfire Counter does not increment for the cylinder where the suspect spark plug was installed.
- If increments
  Replace the spark plug.
- If does not increment
Verify the conditions listed below do not exist:
- A lean or rich Q17 Fuel Injector-Refer to Fuel Injector Balance Test .
- An engine mechanical condition-Refer to Symptoms - Engine Mechanical .