Compression Check: Testing and Inspection

Compression, Checking

Special tools, testers and auxiliary items required

• Spark Plug Removal Tool (3122 B)

• Compression Tester (V.A.G 1763)

• Ignition Coil Puller (T40039)

Procedure

• Engine oil temperature min. 30 °C / 86 °F

• Battery voltage min. 12.5 V

- Switch off ignition.

- Disconnect electrical connector on engine speed (RPM) sensor (G28) - arrow - at right of transmission.





- Disconnect electrical connector - 2 - at Mass Air Flow (MAF) sensor 2 (G246).





- Remove left air guide hose - 1 - from air duct.

- Release retaining clips - 3 - and remove upper left section of air filter housing.

- Disconnect hose - 1 - to Secondary Air Injection (AIR) pump.





- Disconnect electrical harness connector - 4 - at Mass Air Flow (MAF) sensor (G70).

- Remove right air guide hose - 3 - from air duct.

- Release retaining clips - 2 - and remove upper right section of air filter housing from lower part.

Vehicles with air suspension:

• If necessary, remove electrical connector for Heated Oxygen Sensor (HO2S) 2 (G108) from bracket at right strut tower for better access.

- Press circlip - 1 - forward from hose coupling.





- Press release ring - 2 - down - arrows - and remove vent hose - 3 - from upper section of air filter.

All Vehicles

- Remove oil dipstick - 1 - from guide tube.





- Remove the bolts - 2 - and - 3 -.

- Disconnect electrical harness connectors at ignition coils.

- Press electrical wiring harness to side.

- Remove the bolts - 1 - and - 2 -.





- Disconnect electrical harness connectors at ignition coils.

- Press electrical wiring harness to side.

- Remove all ignition coils using (T40039).





- Using (3122 B), remove spark plugs.

- Check compression using (V.A.G 1763).

• Using tester => operating instructions.

- Have a second technician press accelerator pedal completely and at the same time operate starter long enough until pressure increase no longer appears on tester.






Assembly is in reverse order of removal, note the following:

- Install sparks plugs.

- If electrical connectors were disconnected and the engine was started, then malfunctions have been stored in the engine control module. "Generate readiness code" in "Guided Functions" vehicle diagnostic tester.