AC misfire?

[Kasra]

Hey Guys!

I believe I’m having a misfire when I turn on my AC and the car is idling or at the stop. However, once I’m above 2000rpm the misfire is not there (maybe I just can tell).

This is how it feels: mmmmmmmmmm bum mm bum bum mmmmmmmmmmmmmmm bum mmmmmmmmmmmm bum mmmm
Mmmm = idle
Bum = misfire

Also, check engine light does not turn on. I’ve read it could be an old spark plug coil?

Any thoughts or ideas?

Thanks!

Topic

[Rob]

Im thinking more of a bad belt tentioner or bad belt or a vacuum leak more then a misfire.. but maybe others can say… but I would check that out first… also check the ac clutch

[Shaun Flichel]

What year, make, model and engine? The AC compressor does put an additional load on the engine. Does the engine physically shake during this time? Your timing belt can cause a misfire, not the serpentine belt. How many miles are on this vehicle?

[Kasra]

It’s a 2006 BMW 325i. I-6 N52 series engine with 150,000 miles.

[Kasra]

Yes the engine does physically shakes and the rpm drops and recovers quickly. It’s all in a split second

[Author]

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