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      11-20-2011, 07:32 PM   #1
Dr Zoidberg
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Drives: 08' 328i
Join Date: Mar 2011
Location: Gainesville, Va

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Engine noise and erratic idle

2007 328i 70k miles
This is kind of embarrasing since, I take pride in troubleshooting and fixing all my own cars.. but this has be stumped. I admit I have not done too much troubleshooting yet, but since it is still under CPO , I just dropped it on the dealer... so hear it goes..

So I go for a drive on friday, and I hear my car making a minor , squealing belt noise.. Ive hear this before and figure it would just go away. Guessing I may have gotten a drop of oil on the belt when I changed my oil 4 days ago.

I continue to drive and notice the idle is not smooth and while sitting at a light the tachometer is bouncing around. ( in older cars this usually indicates a alternator failure) While the squealing noise is getting worse.

So now I think it is a belt, tensioner or a belt accessory, I inspect the engine bay.

No signs of oil on the belt,
the belts are in good condition ,
there are no shiny makrs on the belts , no rubber powder or transfer on or near any pulley, ( indicating a stuck/sticky pulley . ) and no hot spots

During troubleshooting, I find the noise goes away when I am on the gas, and then comes back when off the gas.

While coming back to my house to change cars.. the car just idles so poorly I had to keep giving it gas,, and then finally the engine just dies..

I start it right back up, and the problem disappeared... sound too.. for awhile.

My voltage is good too,, 14.4 idle and 13.7v cruising

I have replaced many a Alternator or pulley, and this sound is usually constant,

It is loudest from under front/ passenger side of the car..

My other thought is a power steering pump..

what the heck is going on , any help or conjecture would be helpful .

I am hoping its covered under CPO, but I told them to let me know what they found first