View Full Version : Whistle at higher RPM, not boost level related

05-30-2010, 05:48 PM
99.5 1.8T 5 speed, bone stock, except for boost gauge, 98,xxx miles.

Quick read:

No leaks during boost leak test.
Only peaking at 9 psi.
Holds 21 inhg consistently at idle.
Whistle at higher rpm.
Boost will fall to ~2 psi by redline.
No codes.

I am getting a whistle at higher RPM, normally above 4,000. The whistle will come in at as low as 0 psi as I witnessed today. I can build full boost, ~9 psi at very most at a lower RPM and get no whistle until the RPMs get around or above 4,000. It gets louder as the RPMs climb. If I hold it to the rev limiter, only to see how it reacts at higher RPM, I will lose boost, at times it will fall all the way down to 2 psi. I am holding 21 inhg constantly at idle and did a boost leak test late last week. No codes. Great mpgs. Wondering if this could be an exhaust leak either at the turbo or dp. We did try to block off the tail pipes to see if there's a noticeable leak but didn't come up with anything.

06-02-2010, 11:14 AM
Guesses or ideas? Im going to see if the bolts that hold the turbo to the manifold are loose tonight.

ECS Tuning-Audi
06-02-2010, 11:21 AM
A whistle would indicate a vacuum leak or exhaust leak. If you can hear it constantly I'd be inclined to have you look at your exhaust again. Possibly you need to look at your gaskets. This is tricky because once they are separated they really ought to be replaced or you'll be fighting this noise all the time. From what you've said - check out the turbo to cat gasket. Look for signs of leaking, carbon or heat escaping, etc. Replacement gaskets are fairly inexpensive - even for OEM - Click here for replacement gaskets (http://www.ecstuning.com/Audi-B5_A4-Quattro-1.8T/Exhaust/OEM/Gaskets/?salesrep=CArmbruster&utm_source=audizine&utm_medium=forum&utm_content=CArmbruster&utm_campaign=postreply).