Hey guys I'm new here. I have an issue (or so I think) that may be to do with either my turbo or my motor.

I have a 98 a4 1.8t, I recently installed a cone air filter for performance, and of course for the sound of my dv to be louder. However even though I can here my dv now after letting off at 4000 rpms (a sputtering release, turbo surge I'm sure) there is also a tzzzz sound that I hear right after. I can't tell what it is but I have taken a video and I am HOPING someone can help me.

Now I apologize if this issue has already been addressed, and if that's the case modz feel free to direct me in the right direction and cancel this thread.

Anywho here is the link to the YouTube vid, I thank you all in advance.

that sounds like wastegate rattle.

You know that's what I thought too, but when you listen to like the rhythm closely it's sound #1 like its coming from cat and #2 that is might be the back spinning of the turbine?

Reason I think that is because when the dv blows off its flutters (turbo surge) and literally after the blow off you hear the tzzzzzz

The waste gate flange plate is right next to the turbo exhaust turbine and before the cat. What DV do you have?

I have stock dv.

i dont hear turbo surge this is what compressor surge sounds like.


yours sounds like this

Hmmm slightly confused. The videos have the cho cho cho sound. But I don't hear the tzzzz sound.

Although in all of this I forgot to mention, Out of every Audi that I've heard on YouTube with a cone air filter you can hear the diverter valve you can hear the blow off when they are taking video at the engine bay when manually revving the motor... But mine you can't, rather tzzzz

Say it is compressor, what the diff in compressor vs turbo, what's the worse that can happen, can't imagine it's an easy fix

the second video with the bmw sounds more like yours. the first video is what compressor surge sounds like( compressor = turbo. what you actually hear is the compressor side or cold side turbine fins being suddenly stopped in rotation due to pressure spike and the sound is the fins back cutting the air.) <- very bad for turbo it can cause blown seals and broken turbine fins, as well as messing up the throttle body plate.