Engine Not Running on All Cylinders

WARNING: The electronic ignition system generates voltages of 40,000 V. This voltage can prove fatal to people with weak hearts or those who are fitted with pacemakers. The ignition system should therefore be treated with great respect.






FAULT DIAGNOSIS, ENGINE NOT RUNNING ON ALL CYLINDERS

Fault symptom
Engine not running on all cylinders.

DIAGNOSTIC PROCEDURE

1. Identification Of Misfiring Cylinder
Start The Engine And Run It At Idling Speed
Turn off one injector at a time to pinpoint the misfiring cylinder. Do this by unplugging each injector connector in turn.
Listen to the engine to ascertain which cylinder is not firing.
Continue with point 2.


IMPORTANT: The ignition discharge module must be positioned with the ignition coils facing downwards during the step 2 test to ensure that the transformer oil effectively insulates the high-tension part of the ignition coils.





2. Checking The Ignition Discharge Module
Detach the ignition discharge module from the camshaft cover.
Fit a test spark plug (part No.86 11 386) in place of the misfiring cylinder's spark plug.
Use the Scan Tool to activate the ignition coil for the cylinder that has been identified as the misfiring one.
Connect the Scan Tool.
Select "TRIONIC".
Select "ACTIVATE".
Select "IGNITION COILS"
Select "IGNITION CYL1", "CYL2", CYL3" or "CYL4".

If sparks are produced, continue with point 3.

If no sparks are produced, proceed to ignition - misfiring. Ignition - Misfiring







3. Checking The Compression
Check the compression of the cylinder in question.

If the compression test is not OK, further engine examination is needed.

If the compression test is OK, change the spark plug and try to start the engine.

If the fault symptom persists, proceed with fault diagnosis, injectors. Injectors