Compression Test

Compression test

Special tools:
999 9689 COMPRESSION METER 999 9689 Compression Meter
115 8540 EXTENSION 115 8540 Extension

Ignition system
A check for cylinder leakage (also called "leak down") can be carried out instead of a compression test. Cylinder leakage test Component Tests and General Diagnostics





Caution! The ignition system operates at high ignition charges and produces dangerous voltages in both the low and high voltage circuits. There is dangerous voltage throughout the entire ignition system including connectors etc.

Conditions

Note! The engine compression must always be checked with wide open throttle (WOT) and engine at operating temperature.

Preparations

Remove:
- the charge air pipe over the engine to improve accessibility.
- the upper timing belt cover.
- the cover over the ignition coils.
- the ignition coils.
Mark up and put to one side without disconnecting the connectors.
- the spark plugs.

Note! Separate the connector for the engine speed (RPM) sensor.

Compression testing





Note! Compression testing should always be carried out at wide open throttle (WOT) and with the engine at operating temperature. Diagnostic trouble codes (DTCs) will be stored because the engine speed (RPM) sensor and (where applicable) the camshaft position (CMP) sensor have been disconnected.

Have an assistant hold the accelerator pedal (AP) depressed at wide open throttle (WOT) during the compression test.
The starter motor is activated with the ignition key.
The ignition must be switched off after each cylinder has been compression tested.

Note! It will no longer be possible to control the throttle if the ignition is on for longer than 2 minutes. The throttle function is controlled by the control module.

Use compression meter 999 9689 COMPRESSION METER 999 9689 Compression Meter
with extension sleeve 115 8540 EXTENSION 115 8540 Extension.






Install

Install:
- the spark plugs.
Tighten to 25 Nm.
- the ignition coils according to the earlier markings.
Tighten to 10 Nm.
- the cover over the ignition coils.
- the upper timing belt cover.
- the disassembled connectors.
- charge air pipe.
Remove the seals.
Tighten the mountings and hose clamps.

Erase diagnostic trouble codes (DTCs) and check





Erase diagnostic trouble codes (DTCs):
Start the engine. Check that the engine is functioning normally.
Use VIDA vehicle communication to check which diagnostic trouble codes (DTCs) have been stored.
Erase the diagnostic trouble codes (DTCs).
Check the engine compartment. Wipe the engine compartment clean.