Compression Pressure, Checking: Procedure

WARNING: This page is about a different car, the 2012 Audi S5, 2011 Audi S5, 2010 Audi S5, 2009 Audi S5, and 2008 Audi S5. However, it is still accessible from the selected car via links, so may be relevant.

Engine oil temperature: minimum 30 °C (86 °F)
Battery voltage minimum 12.5 V.

-- Remove the rear noise insulation -2-. Refer to NOISE INSULATION .

Fig 1: Automatic Transmission Fluid Oil Pan

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-- Disconnect the connector -2- from the Engine Speed Sensor -G28-.

Fig 2: Disconnect Connector From Servotronic Solenoid Valve

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NOTE:

Ignore item -1-.

-- Remove the air duct -arrows-.

Fig 3: Identifying Air Duct

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-- Free up the fuel line and the line to the Evaporative Emission (EVAP) canister on the air guide pipe.

-- Disconnect the connector -1- from the Mass Airflow Sensor -G70-.

Fig 4: Disconnecting Connector On Mass Airflow (MAF) Sensor

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-- Disconnect the vacuum line -3- from the air guide pipe.

CAUTION:

Risk Of Violating Emissions Legislation On USA Vehicles.

Do not open hose connection -2- !

-- Lay aside air guide pipe with connected crankcase ventilation hose -2- by loosening hose clamp -4- and opening clips -arrows-.

-- Disconnect the vacuum line -1-.

Fig 5: Identifying Secondary Air System Components

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-- Remove the air filter housing and disconnect the electrical connector -2- on the rear side at the Intake Air Switch-Over Valve -N335-.

-- Remove hose -3- from the Secondary Air Injection (AIR) system.

-- Disconnect the coolant hose from -3- from the coolant overflow reservoir.

Fig 6: Identifying Coolant Hose And Coolant Reservoir

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-- Remove the bolts -arrows-.

-- Disconnect the connector on the Engine Coolant Level Warning Switch -F66- and move the coolant overflow reservoir with the coolant hoses -1 and 2- still connected to the side.

-- Pull the oil dipstick -1- out of the guide tube.

Fig 7: Identifying Oil Dipstick, Bolts & Ignition Coils Electrical Harness Connectors

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-- Remove the bolts -2 and 3-.

-- Disconnect the connectors on the ignition coils.

-- Press the electrical wiring harness to the side.

-- Remove the bolts -1 and 2-.

Fig 8: Identifying Bolts & Ignition Coils Electrical Harness Connectors

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-- Disconnect the connectors on the ignition coils.

-- Press the electrical wiring harness to the side.

-- Remove all the ignition coils in direction of -arrow- using the :T40039 .

Fig 9: Identifying Ignition Coil Puller T40039 Removing Ignition Coils

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-- Remove spark plugs with :3122B .

-- Check the compression using the :VAG1763 .

NOTE:

For Information On Using The Tester. Refer To The Operating Instructions.

-- Have a second mechanic press the accelerator pedal down all the way while operating the starter until the pressure increase is no longer displayed on the tester.

-- Repeat Procedure On Each Cylinder.

Compression Pressure	Pressure
New	10 to 14 bar (145 to 203 psi)
Wear limit	9 bar (130 psi)
Maximum difference between cylinders	3 bar (43 psi)

Assemble in reverse order of disassembling. Note The Following:

-- Install the spark plugs. Refer to

-- Install the rear noise insulation. Refer to NOISE INSULATION .

There will be faults stored in the engine control module Diagnostic Trouble Code (DTC) memory because the connectors were disconnected.

-- Generate Readiness Code in Guided Functions . Refer to Vehicle Diagnostic Tester.