[mybimmerlife]

Hey guys so i need a little help and advice. My car runs great still has its get up and go and no problems. Slight jitters when i first start the engine (rpms bounce and car has slight lurching) but they disappear when i start driving. Well just recently the SEL came on. Went to OReilleys and had the codes ran, pulling up the dreaded cat codes, Both bank one and two. Would replacing the cat fix this issue? If so how diffucult is it? Im pretty good at figuring things out so anything short of welding and I can do it. Also would replacing the whole exhaust system fix this?

Thanks for your help.

[Punisher3.0si]

95% of the time it's cats that are bad. Especially with over 100k. Assuming you have a 3.0 engine you would have to get new manifolds because they are built into them. Great time to get AA headers and a tune.

[mybimmerlife]

Originally Posted by Punisher3.0si

95% of the time it's cats that are bad. Especially with over 100k. Assuming you have a 3.0 engine you would have to get new manifolds because they are built into them. Great time to get AA headers and a tune.

So instead of searching for "bmw e90 [cc]" I should search for "bmw e90 exhaust manifold"? And you mention new headers as well. What advantages do those bring? HP gain or just better responsiveness?

[Dan Bilzerian]

Originally Posted by mybimmerlife

So instead of searching for "bmw e90 [cc]" I should search for "bmw e90 exhaust manifold"? And you mention new headers as well. What advantages do those bring? HP gain or just better responsiveness?

New headers from what it sounds like is having a whole new car, but you have to get the tune as well!

[mybimmerlife]

Originally Posted by Dan Bilzerian

New headers from what it sounds like is having a whole new car, but you have to get the tune as well!

I was reading on the AA headers page that i could probably install the headers my self. So thats not an issue. However what kind of tune is needed? And how much do those generally run? I already dont have money for this lol so Im doing what i can. Im also not quite understanding exactly where the cc are. Are they located towards the tail end of the headers? In all my other cars they have been a stand alone unti. But as he mentioned above they are built into the manifold. So im taking a shot in the dark and saying the headers are the same thing as the manifold?

[Punisher3.0si]

Yes the AA headers replace the exhaust manifolds (catless). The tune prevents the codes from coming back. That all costs money though. Either way though it's not going to be cheap.

[mybimmerlife]

Originally Posted by Punisher3.0si

Yes the AA headers replace the exhaust manifolds (catless). The tune prevents the codes from coming back. That all costs money though. Either way though it's not going to be cheap.

Being catless in my state is illegal. So now im faced with the option of running it illegally, which isnt a huge concern except i have annual inspections.

[3002 tii]

Originally Posted by mybimmerlife

Being catless in my state is illegal. So now im faced with the option of running it illegally, which isnt a huge concern except i have annual inspections.

If it's visual then you'll fail. But if you go custom catback, you could install your own [high flow] cats downstream. That plus a tune might allow you to pass since you won't have any codes and the inspector will see some cat underneath the car. Else aFe sells headers with high flow cats.

If it's obd and they allow 1 incomplete readiness, you might pass with a tune.