ok. i have a 98 audi a4 with 127k miles. i bought the car with one problem. the wastegate was shot and the car hasnt seen boost for who knows how long. anyways it drove great just not quick. a month ago the icm went out and just replaced it yesterday. at the same time i replaced the wastegate and installed a 3" cat delete pipe. when i started it up all ignition coils were firing and the turbo was spooling, but now a have another different problem. it sputters and accellerates rough after 2k rpms, usually when more throttle is applied. i took my a4 to autozone to see what codes it was throwing and found 4 air/fuel codes, 2 o2 sensor codes, and a mass air flow sensor code. any ideas what my problem could be? please help me out. thanks

 

1. You can't run a test-pipe (cat delete) without non-foulers for the O2s or tuning.

2. Post the code numbers (PO or Audi specific).

 

thanks for the reply. what are non-foulers? ive heard that the ecu needs tuned for the cat delete, but how much would that cost me and where can i get it done at? whats the cheapest way? i will be sure to post the code numbers tomorrow around noon. i gotta go back n get em

 

also i was told when i bought the cat delete that it would just throw converter codes without harming the performance of the engine. is this obviously false?

 

False. Secondary O2 sensor codes (depending on the code) can still put the car in limp mode, resulting in poor boost. Your better off with a high flow cat from Labree than a huge test-pipe, especially with a stock turbo.

A non-fouler is essentially a spacer to trick the secondary O2 into reading as if there were a cat installed.

The only tune I know of that eliminates the secondary O2s is companies such as European Performance Labs (CT) that flash the stock ECU. It's much cheaper to go with a chip from a company such as AWE, REVO, or APR and run non-foulers. Search the forum for these topics.

But in order to help you, I really need to see the code numbers (PO or Audi specific). There are literally hundreds of codes for engine performance, all with very specific meanings and conditions.

 

ok. so is there a certain size non fouler to buy? i found 14mm long or short non foulers for $3+ship. thanks for your help