Audi Workshop Service and Repair Manuals

Checking compression

Special tools and workshop equipment required

t	Spark plug socket and extension -3122 B-

t	Compression tester -V.A.G 1763-

t	Puller -T10094-

t	Assembly tool -T10118-

Test conditions l  Engine oil temperature at least 30 °C. l  Battery voltage at least 12.5 V

Test sequence –  Switch off ignition. –  Open lid of electronics box in engine compartment and remove fuse -26- for Motronic current supply relay -J271-.

–  Unclip air intake hose from air duct -arrows-.

–  Unplug electrical connector at intake air temperature sender 2 -G299--item 2-. –  Detach vacuum hose -1- from actuator for intake air preheater.

–  Pull dipstick -1- out of guide tube. –  Remove the engine cover together with air cleaner housing -arrows-. –  Re-insert dipstick in guide tube.

–  Apply puller -T10094- at ignition coil -arrow- and pull out ignition coil slightly. –  Detach electrical connectors at ignition coils by releasing tab -arrow- with assembly tool -T10118- and carefully pulling connector. –  Remove ignition coils. –  Remove spark plugs with spark plug socket -3122 B-. –  Test the compression pressure with the compression tester -V.A.G 1763-.   Note Using the compression tester → Operating instructions. –  Have a 2nd mechanic press down the accelerator pedal completely and simultaneously operate the starter until the pressure no longer increases on the tester display.

Compression pressure	bar
When new	10.0 … 15.0
Wear limit	7.0
Difference between cylinders	max. 3.0

Installation is carried out in the reverse order; note the following: –  Install spark plugs → Rep. Gr.28. –  Interrogate and erase the fault memory for engine control unit, as faults are stored when the connectors are unplugged → Vehicle diagnosis, testing and information system VAS 5051.