Loud knocking sound at the valves.

M3 Eater · 12-13-2010, 08:52 AM

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.

welkerbrads · 12-15-2010, 06:25 PM

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?

12-13-2010, 08:52 AM	#1
M3 Eater Major 36 Rep 1,054 Posts Drives: 335i Sedan Join Date: May 2010 Location: Unknown iTrader: (3) Garage List 2007 335i [0.00]	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. __________________ JB4 beta 15 ohms FSB,AEM inline filter/ CM 10, ETS fmic, ER custom made charge pipe,TSW Donnington 18's,Simitumo HTRZ3, Injen DCI, AR DPs, Forge DVs, AA SLD, Koni FSD, ZSP springs.
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12-15-2010, 06:25 PM	#2
welkerbrads Private First Class 10 Rep 120 Posts Drives: 2011 white X3 Join Date: Apr 2009 Location: cape girardeau mo iTrader: (0)	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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