Vehicle applicability: This diagnostic supplement covers multiple Ford vehicles and engines. Follow the application named in the source below. Some references apply to vehicles other than Mustang.
JC8 CHECK FOR LOW SPARK PLUG FIRING VOLTAGE
Is there consistently low spark plug firing voltage or sloping sparkline on one or more cylinders?
Yes | No |
|---|---|
INSPECT the spark plug wires for missing cylinders. MEASURE the resistance of the spark plug wires. INSTALL a new spark plug wire if the resistance is greater than 7,000 ohms per 30.5 cm (1 foot). MEASURE the resistance of the spark plugs. INSTALL a new spark plugs if the resistance is lower than 2,000 or higher than 12,000 ohms. REFER to the Workshop Manual Section 303-07, Engine Ignition. Clear the PCM DTCs. REPEAT the self-test. | GO to JC9 . |
JC9 CHECK FOR EVENNESS BETWEEN CYLINDERS
• Check the spark plug firing voltage average pattern.
Is the evenness of spark plug firing voltage greater than 6 kV?
Yes | No |
|---|---|
INSPECT the spark plug wires for missing cylinders. MEASURE the resistance of the spark plug wires. INSTALL a new spark plug wire if the resistance is greater than 7,000 ohms per 30.5 cm (1 foot). CHECK for damaged spark plugs or narrow spark plug gaps. MEASURE the resistance of the spark plugs. INSTALL a new spark plugs if the | GO to Pinpoint Test Z . |
2016 Mustang workshop publication supplied to Mustang Atlas. Original technical text and illustrations; HTML formatting by Mustang Atlas. Source page numbering is retained for traceability. Follow the configuration, revision, warnings, and cross-references in the material. About this edition.