Compression, Checking

WARNING: This page is about a different car, the 2009 Audi S8, 2008 Audi S8, and 2007 Audi S8. However, it is still accessible from the selected car via links, so may be relevant.

Special tools, testers and auxiliary items required

Fig 1: Identifying Special Tools - Compression, Checking

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Spark plug removal tool 3122 B
Compression tester V.A.G 1763
Ignition Coil Puller T40039

Procedure

Engine oil temperature min. 30 C.
Battery voltage min. 12.5 V.

Switch off ignition.

Fig 2: Identifying Exhaust Pipe Fasteners

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For vehicles with auxiliary heater, remove bolts - arrows - for exhaust pipe of parking heater/auxiliary heater on noise insulation.

Fig 3: Noise Insulation Quick-Release Fasteners

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Loosen quick-release fasteners - 1 - and remove front noise insulation.

Fig 4: Disconnecting Electrical Connector On Engine Speed (RPM) Sensor G28

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Disconnect electrical connector on Engine Speed (RPM) Sensor G28 - arrow - at bottom of transmission.

Fig 5: Removing Front Engine Cover And Rear

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Remove front engine cover - 1 - and rear - 2 - - arrows -.

Fig 6: Left Air Duct Hose, Hose Clamps & Air Guide Hose Vacuum Hose

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Remove left air duct hose - arrows -.

Fig 7: Oil Dipstick, Bolts & Vacuum Hose

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Remove oil dipstick - 2 - from guide tube.
Remove bolts - 1 - and - 3 -.
Disconnect electrical connectors to ignition coils and press wiring harness to side.
Disconnect vacuum hose - 2 - from air guide hose.

Loosen hose clamps - arrows - and lay aside air guide hose.

CAUTION: Hose connectors - 1 - must not be opened.

Fig 8: Ignition Coil Electrical Harness Screws

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Remove bolts - 1 - and - 2 -.
Disconnect electrical connectors to ignition coils and press wiring harness to side.

Fig 9: Removing Ignition Coils Using Ignition Coil Puller T40039

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Remove all ignition coils using Ignition Coil Puller T40039.
Using spark plug removal tool 3122 B , remove spark plugs.
Check compression using compression tester V.A.G 1763.

NOTE:

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.

Compression pressure	Bar pressure
New	10.0 to 14.0
Wear limit	9.0
Difference between cylinders	max. 3.0

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

Install spark plugs → 28 - IGNITION/GLOW PLUG SYSTEM .
As a final step, check Engine Control Module (ECM) DTC memory and erase it, since malfunctions were stored by disconnecting electrical connectors

Tightening specifications

Component	Nm
Wiring for ignition coils at cylinder head cover	5