BMW 325i N53 Engine - Misfire

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Tue 22 Aug 2023 08:11
BMW 325i N53 Engine - Misfire - Luke@GDA

Hi,

We have an ongoing issue with a customers car.

2010 BMW 325i N53 Engine. Not N52 as listed.

The car has had a misfire issue for a while. It happens mainly in the first few miles from cold but has a slight hesitation at times.

29CF - misfire cylinder 3 has been the ongoing fault code.

Other misfire codes have flagged at times but 29CF is the one that keeps returning.

The other codes have been:

2A2B 29D1 29D0 29CC

I have switched ignition coils and spark plugs to see if the fault moved cylinder. It hasn't, still cylinder 3.

I have scoped the ignition and injectors and compared the waveforms. Cylinder 3 doesn't show any differences to the other cylinders.

Oxygen sensors look OK on live data and respond as expected when forcing a rich mixture. Plus I can't see how an oxygen sensor would only cause a misfire in cylinder 3.

It's also difficult to get readings when the misfire is present as it only happens for a short time when cold.

Any thoughts gratefully received.

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Tue 22 Aug 2023 09:03
BMW 325i N53 Engine - Misfire - elekie&a/c doctor
This is a hi pressure injection system , so possibly a faulty injector or a clogged up air inlet tract . You’ll probably need to remove inlet manifold for inspection.
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