Compression Check: Testing and Inspection

Engine Compression Inspection

NOTE: After this inspection, you must reset the ECM/PCM. Otherwise, the ECM/PCM will continue to stop the fuel injectors from operating.

1. Warm up the engine to normal operating temperature (cooling fan comes on).

2. Turn the ignition switch to LOCK (0).

3. Connect the HDS to the DLC.

4. Turn the ignition switch to ON (II).

5. Make sure the HDS communicates with the vehicle and the ECM/PCM. If it does not communicate, troubleshoot the DLC circuit Testing and Inspection.

6. Select ALL INJECTORS STOP in the PGM-FI INSPECTION menu with the HDS.

7. Turn the ignition switch to LOCK (0).

8. Remove the four ignition coils and the four spark plugs Service and Repair.

9. Attach a compression gauge to the spark plug hole.






10. Step on the accelerator pedal to open the throttle fully, then crank the engine with the starter motor, and measure the compression.





11. Measure the compression on the remaining cylinders.





12. If the compression is not within specifications, perform a cylinder leak down test to determine the problem area. Then check the following items, and remeasure the compression:

- Incorrect valve clearance
- Confirmation of cam timing
- Damaged or worn valves and seats
- Damaged cylinder head gasket
- Damaged or worn piston rings
- Damaged or worn piston and cylinder bore

13. Remove the compression gauge from the spark plug hole.

14. Install the four spark plugs and the four ignition coils Service and Repair.

15. Select the ECM/PCM reset in the PGM-FI INSPECTION menu to cancel ALL INJECTORS STOP with the HDS.