Whistling noise, please help!
01-01-2002, 09:48 AM
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Whistling noise, please help!
Last time I had a problem, you guys solved it for me. This time it is something new. At certain RPMs in 1-3 gears, there is a whistling sound that is getting rather annoying. It didn't start till it has gotten cold in my area. I have heard that there is a valve dealing with the turbo sometimes go bad with certain aftermarket chips (I have a Wett chip), could this be my problem. Also, the car had 53,000 miles, is it time perhaps to change all my hoses into and out of the intercooler. Thanks for any input you can give me.
01-02-2002, 07:37 PM
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lemme guess.....
It probably happens under accelleration around 2800 to 3200 rpm, and only on cold days when the engine is cold. It sounds like a coke bottle whistle, and it goes away after the engine warms up... right?
If that is the case, this is a VERY common and well documented issue with the A4 1.8t. So far, nobody has been able to really explain to my satisfaction why this happens. Other than that it is believed to be coming from the diverter (bypass) valve. However, the consensus is that, although it can be slightly annoying, it is a harmless phenomena.
My best guess, is that the stock A4 bpv is not strong enough to hold in boost on a chipped car. So maybe it opens slightly under the higher boost pressure. Couple that with the fact that the rubber gaskets inskde the valve probably stiffen up a bit in cold weather.. I'd bet that the valve opens juuuuuuust barely... and allows the air to whistle through.
Some people have successfully eliminated this problem by switching to a TT diverter valve. Since it is designed to hold in the stronger boost of the 225TTQ, maybe it won't leak. I plan to do this mod on my car. If it doesn't solve the issue, it's only $30 bucks.
If that is the case, this is a VERY common and well documented issue with the A4 1.8t. So far, nobody has been able to really explain to my satisfaction why this happens. Other than that it is believed to be coming from the diverter (bypass) valve. However, the consensus is that, although it can be slightly annoying, it is a harmless phenomena.
My best guess, is that the stock A4 bpv is not strong enough to hold in boost on a chipped car. So maybe it opens slightly under the higher boost pressure. Couple that with the fact that the rubber gaskets inskde the valve probably stiffen up a bit in cold weather.. I'd bet that the valve opens juuuuuuust barely... and allows the air to whistle through.
Some people have successfully eliminated this problem by switching to a TT diverter valve. Since it is designed to hold in the stronger boost of the 225TTQ, maybe it won't leak. I plan to do this mod on my car. If it doesn't solve the issue, it's only $30 bucks.
01-07-2002, 06:32 AM
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Actually, I suspect it is the belt tensioner..
I get the same thing in cold weather. In my case it is a screeching sound, and sounds exactly like my previous car, where I knew for a fact it was the tensioner bearing.
A few people tried having the tensioner replaced under warranty when this first started getting reported, but this only corrected the problem for a short time, then the noise returned.
A bad BPV does not make a screeching sound that I know of. From what I understand, it's a different noise (I haven't had this problem).
Paul
A few people tried having the tensioner replaced under warranty when this first started getting reported, but this only corrected the problem for a short time, then the noise returned.
A bad BPV does not make a screeching sound that I know of. From what I understand, it's a different noise (I haven't had this problem).
Paul
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