Compression Check: Testing and Inspection

Engine Compression Test

Special Tools

EN-48248 - Cylinder Compression Pressure Gauge

For equivalent regional tools, refer to Special Tools Tools and Equipment.

Removal Procedure

1. Remove the throttle body assembly. Refer to Throttle Body Assembly Replacement Removal and Replacement.

2. Remove the spark plugs. Refer to Spark Plug Replacement Service and Repair.

3. Remove the relay holder cover.

4. Remove the fuel pump relay.

Note: The engine cranking time for the compression test should be less then 10 seconds and at 30 second intervals.

5. Crank the engine with the starter motor for 5 seconds to remove any foreign substances from the cylinders.

6. Prior to taking a compression reading, verify the cranking speed is greater than 300 RPM. If the cranking speed is below 300 RPM, repair the slow cranking speed condition before continuing with the compression test.

7. Install EN-48248 - gauge in the spark plug bore for the cylinder that is being checked.

8. Using the vehicle's starter motor, rotate or crank the engine for 4 compression strokes, puffs, for the cylinder being tested.

9. Observe the compression gauge and note the reading as the compression test is being performed. A normal cylinder reading will be indicated if compression builds up quickly and evenly to the specified level. An abnormal reading will be indicated if compression is low on the first compression stroke, starts increasing on the following compression strokes but does not reach the specified level.

10. Record the compression reading for the cylinder just tested.

11. Repeat steps for all remaining cylinders. All 4 cylinders must be tested to obtain valid test results. Record the readings.

12. The maximum pressure differential should not exceed 100 kPa (14.5 psi).

13. The nominal cylinder compression value is

* for natural aspirated engines 1300 kPa - 1500 kPa (188.5 psi - 217.6 psi).

* for turbo engines 1200 kPa - 1400 kPa (174 psi - 203.1 psi).

Installation Procedure

1. Install the fuel pump relay.

2. Install the relay holder cover.

3. Install the spark plugs. Refer to Spark Plug Replacement Service and Repair.

4. Install the throttle body assembly. Refer to Throttle Body Assembly Replacement Removal and Replacement.