Circuit/System Testing
- Verify none of the following 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
- If a condition exists
- Ignition OFF, remove the appropriate T8 Ignition Coil from the spark plug and connect the EL 26792 HEI Spark Tester 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
- If no output or the output is weak
- 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 1-4 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
- If increments
- Test or inspect for the conditions listed below:
- A lean or rich Q17 Fuel Injector-Refer to Fuel Injector Diagnosis .
- An engine mechanical condition-Refer to Symptoms - Engine Mechanical .
NOTE:
An erratic or weak spark is considered a no spark condition.