I just purchased a 2000 a4 quattro with the 1.8t and the guy I bought it from made a custom exhaust that sounds nice but he deleted the catalytic converter. The car idles a little rough when in drive or reverse. Could this be because the catalytic converter is missing? I also have my check engine light on because of this. If it is the cat where could I buy a universal one that I could put in it to hopefully fix the idling problem?

All info is much appreciated,
Thanks

 

Firstly how do you know there is not another issue causing the check engine light? Second you might have a fouled o2 sensor and if that is so buy a new one and if you continue to run a test pipe, get some o2 sensor spacers. There are plenty of threads on here that tell you what to do to get them spaced and fitted right. If you plan on putting on a new cat, a universal one will not work, because of it's location and fittings connecting right to the turbo. You have to go oem or with a high flow cat which are both fairly expensive. Ecs tuning, 034 motorsports, are both places you can look around.

 

Well first off I would assume that its the cat because I do not have one. That is why I was going to start there. I was just wondering if anyone has had the similar issue when they have deleted the cat. The code I got was p0411. I can not go with an oem cat because I have an aftermarket exhaust. So a universal one is what I need.