98audiqtt

I have a 1998 audi a4 1.8t awd. I bought the car with the cel light on and it gives 2 codes.

1.) P1565 - Dirty Throttle Body
2.) P0422 - Faulty Cat Converter

The car passed emissions last Monday and has a new oil change. The lady who i bought the car form said the CEL came on after someone test drove it a few hours before i bought the car.

It blows white smoke out the exhaust when it is at idle. I put a boost gauge in the car today and when i am driving it seems to only go over the vac 0 maybe an inch.. i think the turbo is blown?

98audiqtt

It seems slow on acceleration also.

4Driver4

Gotta do more diagnostics than that.

I did not know there was a code for "dirty throttle body".

AudiMick

Strictly speaking that's the position switch on the throttle body not being set. It could be dirt but it could also be a bad TB or it needs an adaptation.

P0422 could be a cat converter, but it could also be upstream at the turbo (impeding flow) causing a problem.

Can you hear the turbo spool, hope you bought it cheap. You should have 7-10psi at least. Check the wastegate, to see if it's closing.

98audiqtt

i did get it cheap, how do i check the wastegate?

AudiMick

Get a mirror and look at it.

4Driver4

With the codes he's seeing, wouldn't it be less intrusive and make more sense to check for boost leaks and check the BPV first?

Pete@ECSTuning

Have you tried a boost leak test??

Pete

AudiMick

Got the white smoke thing going on, that seems to be related to turbo health.

If he's only getting 1 psi of boost, that's a pretty big leak I would expect more codes.

4Driver4

Hard to argue with that. I'm curious because I have basically the same issue minus one pound of boost and minus the smoke. I've been all through the car and can't figure it out. Will be replacing the turbo this weekend.