Commander 4WD V8-4.7L VIN N (2006)
Compression Check: Testing and Inspection
CYLINDER COMPRESSION PRESSURE
The results of a cylinder compression pressure test can be utilized to diagnose several engine malfunctions.
Ensure the battery is completely charged and the engine starter motor is in good operating condition. Otherwise the indicated compression pressures
may not be valid for diagnosis purposes.
1. Clean the spark plug recesses with compressed air.
2. Remove the spark plugs.
3. Secure the throttle in the wide-open position.
4. Disable the fuel system.
5. Remove the ASD relay.
6. Insert a compression pressure gauge and rotate the engine with the engine starter motor for three revolutions.
7. Record the compression pressure on the 3rd revolution. Continue the test for the remaining cylinders.
8. Refer to SPECIFICATIONS for the correct engine compression pressures.
