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BMW N57 Diesel engine, rough running from cold

Issue

From cold start, the engine runs rough/misfires for a couple of minutes then smooths out. Will not repeat until another cold start. Possible glowplug codes stored.

Cause

Fault in glowplug elements and controller, combined with excessive carbon build up creates a smooth running issue.

Action

Connect your Autologic device and carry out a quick test.

If you only have faults for glowplugs, or a glowplug controller fault, then please proceed as follows:

  1. Remove the inlet manifold.
  2. Inspect for carbon build up on the back of the inlet valves and in the inlet ports. Carry out a cylinder head de-coke to remove the excessive carbon deposits. This can be done without removing the head.
  3. Clean/replace the inlet manifold.
  4. Fit genuine glowplugs and controller.
  5. Update the DDE as there is modified software to improve the smooth running and use of the glowplugs from a cold start.