Operation CHARM: Car repair manuals for everyone.

Compression Check

1. Start and warm engine to operating temperature.
2. Remove all spark plugs and apply a few drops of engine oil into spark plug holes.
3. Relieve fuel system pressure as outlined under Precautions.
4. Disable ignition system, by removing ignition fuse.
5. Connect a tachometer and crank engine, ensure cranking speed is 300 RPM or higher.
6. Install compression gauge, then crank engine with throttle wide open.
7. Minimum pressure should be 128 psi.