Checking compression

Special tools and workshop equipment required

Spark plug socket and extension -3122 B-

Compression tester -V.A.G 1763-

Procedure

Engine oil temperature at least 30 °C.

Battery voltage at least 12.5 V

• Remove fuse for fuel pump control unit from fuse holder. Fuse assignment → Current flow diagrams, Electrical fault finding and Fitting locations

Note

Removing fuse interrupts voltage supply for fuel pump control unit.

• Start engine and run it until it turns off.
• Switch off ignition.

• Release hose clips -1- and -2-, and remove air pipe.

• Pull off connector -2- and unscrew bolt -1-.
• Pull out ignition coils with output stages.
• Unscrew spark plugs using spark plug socket and extension -3122 B-.
• Check compression using compression tester -V.A.G 1763-. Refer to → operating manual for information on how to use it.
• Have a second mechanic press down accelerator completely and simultaneously operate starter until pressure no longer increases on tester display.
• Repeat procedure on each cylinder.

Reassembly

Installation is carried out in the reverse order; note the following:

• Install spark plugs.
• Install ignition coils with output stages → Chapter.
• Entries are stored in the event memory of the engine control unit because electrical connectors were disconnected and the engine was started: Generate readiness code in Guided functions → Vehicle diagnostic tester.

Specified torques

→ Chapter „Assembly overview - ignition system“