Compression Check: Testing and Inspection

Checking Compression of All Cylinders
- Read out fault memory of DME control unit
- Check stored faults
- Rectify faults
- Clear fault memory

Disconnect fuel pump relay or fuel pump fuse.
Start engine and allow remaining fuel to escape.
This prevents fuel from being injected, the catalytic converter from being damaged and the test result from being distorted during the compression pressure check.

Caution: High tension - danger!

Disconnect all supply leads from ignition coils (interrupt power supply to ignition coils).

- Remove lower microfilter section (E46 only)
- Remove ignition coil cover
- Remove ignition coils
- Remove all spark plugs





Note: Check that sealing ring is in perfect condition on special tool 110235.

Screw special tool 11 0 235 by hand into spark plug thread and connect special tool 11 0 224.
Depress accelerator and actuate starter until compression stops rising.
Compression pressure, refer to Specifications.

Now clear the fault memory.