Compression, Checking

WARNING: This page is about a different car, the 2024 Audi Q5 e, 2024 Audi Q5, 2023 Audi Q5 e, and 2023 Audi Q5. However, it is still accessible from the selected car via links, so may be relevant.

Special tools and workshop equipment required

Spark Plug Removal Tool:3122B

Fig 1: Identifying Spark Plug Removal Tool 3122B
Courtesy of AUDI
Compression Tester Kit:VAG1763

Fig 2: Compression Tester Kit VAG 1763
Courtesy of AUDI
Adapter:VAG1763/13 , not illustrated

Test Sequence

Engine oil temperature at least 30 °C (86 °F)
Battery voltage at least 12.7 V.

-- Remove the engine cover. Refer to ENGINE COVER, REMOVING AND INSTALLING .

-- Disconnect the fuel injector connector -arrow-.

Courtesy of AUDI

-- Remove the ignition coils. Refer to IGNITION COILS, REMOVING AND INSTALLING .

-- Remove the spark plugs using the Spark Plug Removal Tool:3122B .

Courtesy of AUDI

-- Install the Adapter:VAG1763/13 as shown in the respective spark plug hole and connect the Compression Tester Kit:VAG1763 .

Courtesy of AUDI

-- Check the compression using the Compression Tester Kit:VAG1763 . Refer to the appropriate Operating Information.

-- Have a second technician press the accelerator pedal all the way down and operate the starter at the same time, until a pressure increase is no longer displayed on the tester.

-- Repeat the procedure on each cylinder.

Compression Pressure	Pressure
New	16.0 to 19.0 bar (232.06 to 275.57 psi)
Wear limit	12.0 bar (174.04 psi)
Maximum difference between cylinders	3.0 bar (43.51 psi)

TIP:

If the test with the Compression Tester Kit:VAG1763 does not lead to a clear result there are two additional tests.

In addition to the compression test a pressure test can be performed with the Pressure-Loss Tester:VAS522001 . The procedure for this is described in the operating instructions for the Pressure-Loss Tester:VAS522001 .
As an additional test the CO2 content in the coolant expansion tank can be measured. A raised CO2 content in the cooling system indicates a leak between the combustion chamber and the cooling system. The CO2 content can be determined using the CO2 Coolant Tester:VAS531009 . The procedure for this is described in the operating instructions of the CO2 Coolant Tester:VAS531009 .

Assembling

-- Install the spark plugs. Refer to OVERVIEW - IGNITION SYSTEM .

-- Install the ignition coils. Refer to IGNITION COILS, REMOVING AND INSTALLING .

-- Install the engine cover. Refer to ENGINE COVER, REMOVING AND INSTALLING .

-- Delete the DTC memory entries in the Engine/Motor Control Module that have occurred during the test using the Vehicle Diagnostic Tester.