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.

Test Procedure

Bring vehicle into service bay and connect electrical power the charge port.

1. Remove the ignition coils. Refer to Ignition Coil Replacement Service and Repair.

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

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

Note:
In order to perform the compression test it will be necessary to use a scan tool to crank engine.

Note:
If engine does not crank when CRANK is selected on the compression test diagnostic screen the theft deterrent feature has become active. Therefore it will be necessary to cycle the start/stop switch to reset this feature. After 10 seconds the theft deterrent feature becomes active and the compression test will not run.

Note:
In order to stop the engine from cranking you must select CRANK ABORT on the Compression Test screen.

3. Crank the engine using the scan tool for 5 seconds to remove any foreign substances from the cylinders.

4. 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.

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

6. Using the Compression Test function on the scan tool, rotate or crank the engine for 4 compression strokes, puffs, for the cylinder being tested.

7. 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.

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

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

10. Maximum pressure differential 100 kPa (14.5 psi).

11. Remove EN-48248 - gauge.

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

13. Install the ignition coils. Refer to Ignition Coil Replacement Service and Repair.