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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Technical Forums > Mechanical Maintenance: Break-in / Oil & Fluids / Servicing / Warranty > Loud knocking sound at the valves.

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      12-13-2010, 10:52 AM   #1
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Loud knocking sound at the valves.

Every now and then, I will hear a loud knocking sound coming from the intake manifold. It sounds a bit like someone is hitting metal with a hammer and it has a little steam engine sound to it too like blast of air is passing by when I hear it. Car is warm, usually when I hear it, no heavy loads or logs but after a normal 30-40 min drive I will hear it once every 60 days at idle. There is no performance loss but when I pulled into work today i heard it start as I pulled into my parking spot so I jumped out of the car and popped the hood to see if I could pinpoint the origin. My best guess, cylinder # 3 or the injector assocaited with it. Its on cadence with the running sound of the car. I have been running a tune for almost a year and meth for about 6-7months. All injectors have been replaced within the last 6 months. If I had to guess... it sounds like the engine knocking but when I hear it, the engine is not under load. I am currently on map 8, using meth but I was under the impression that it didn't make a difference while at idle. I can set my daily map to 3 or 5 and have it jump to 8 when the meth is spraying if that is the case.
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      12-15-2010, 08:25 PM   #2
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Question Knocking Noise

I have a 08 328i with 35000 miles on it. Twice now mine has done the same thing. It sounds to me like a rod knocking or a lifter. Rev the engine and then finally goes away. While idling has a low tapping noise. I wonder if it isn't bad gas?
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