I purchased my 99 1.8t in feb been a good car upon buying it I replaced coils, Injectors and sparkplugs just because. About 3 weeks after having it I replaced the cam sensor it went bad . Then couple weeks later started to get some exaust leaks between turbo and manifold and precat and turbo new gaskets the leaks kept coming back I noticed the bolts that bolt the turbo to manifold kept coming loose put some lock tight it still kept happening so I used some exaust sealer that hardens and by that point it was leaking between turbo and precat so sealed it all up then I noticed my turbo getting ret hot right before the cat. And my new problem of not being able to rev above 2000 rpm and its intermittent freaks out the snaps back to normal but it's getting worse and worse and ofcourse the exaust leaks are back. I've have cats collapse on other cars but there was no back and forth it was clogged and done . Anyhow I'm sure it collapsed and its making all kinds of noise now . i ordered a new resonated downpipe to get rid of . I'm looking for some from you guys and what you thing will be greatly appreciated . O and btw it's now throwing up a code for therear o2 sensor. My research tells me that a bad sensor would not affect drivability

 

You are correct the O2 sensor wont cause drive ability issues.. I would look at the Cam sensor you replaced as the cause for the 2000RPM limit.. That and the crank sensor are really the only things I can think of for limiting the RPMs.. I have never heard of the exhaust leak issues you are having in my experiences, so I can't help much there...

 

I will definatly look at the new sensor and its the crank/camshaft position sensor. And I don't think am exhaust leak is causing the issue I think the pre cat collapsed and as a result I pressure is causing the leaks

 

Checked the sensor ohm meter says its fine.