Compression Check: Testing and Inspection

Compression Check
1. Check that the battery is fully charged. Recharge it if necessary.
2. Warm up the engine to the normal operating temperature, then stop it.
3. Allow about 10 minutes for the exhaust manifold to cool.
4. Remove the front and rear trailing-side spark plugs.
5. Disconnect the fuel pump relay and the igniter connector.











6. Connect the SST to the front rotor housing and the battery.





7. Fully depress the accelerator pedal and crank the engine for 5 to 10 seconds.
8. Record the compression of the three combustion chambers and cranking speed.

Compression:
690 kPa (7.0 kgf/cm2, 100 psi)-250 rpm.
Differential limit between chambers:
150 kPa (1.5 kgf/cm2, 21 psi).
Differential limit of rotors:
98 kPa (1.0 kgf/cm2, 14 psi).

1) If pressure is below 290 kPa (3.0 kgf/cm2, 43 psi) at one or two chambers of a rotor, the tester indicates one correct measurement and two 00.0 readings.
2) If pressure is below 290 kPa (3.0 kgf/cm2, 43 psi) at three chambers, the tester indicates three 00.0 readings.
3) In the above cases, the cranking speed readings are all 00.0.

9. Check the rear chambers by using the same procedure.
10. Compensate the compression values if they are measured at cranking speeds other than standard or if they are measured at high altitude.





Cranking speed compensation
Compensate the compression according to the cranking speed.





Altitude compensation
Compensate the compression according to the altitude.