Compression Check: Testing and Inspection

NOTE: If there is lack of power, excessive oil consumption or poor fuel economy, measure the compression pressure.

1. Warm up engine to normal operating temperature, then stop engine.
2. Remove throttle body and intake air connector assembly, refer to Powertrain Management.
3. Disconnect high-tension wires from cylinder head covers.
4. Remove spark plugs.
5. Disconnect injector connectors.
6. Disconnect distributor connector.
7. Check cylinder compression as follows:
(a) Insert a compression tester into the spark plug hole.
(b) While cranking the engine, measure the compression pressure.

NOTE: Always use a fully charged battery to obtain engine revolutions of 250 RPM or more.

(c) Repeat steps (a) and (b) for each cylinder.

NOTE: This measurement must be done in as short a time as possible.

Standard pressure: 1275 kPa (185 psi) or more.
Minimum pressure: 1,079 kPa (156 psi).
Cylinder Differential: 98 kPa (14 psi) or less.
(d) If the cylinder compression in 1 or more cylinders is low, pour a small amount of engine oil into the cylinder through the spark plug hole and repeat steps (a) through (b) for the cylinder with low compression.

NOTE:
- If adding oil helps the compression, it is likely that the piston rings and/or cylinder bore are probably worn or damaged.
- If pressure stays low, a valve may be sticking or seating improper, or there may be leakage past the gasket.

8. Reconnect distributor connector.
9. Reconnect injector connectors.
10. Reinstall spark plugs.
11. Reconnect high-tension wires to cylinder head covers.
12. Reinstall throttle body and intake air connector assembly.