I installed the full ATP GT28RS turbokit (manifold, turbo, downpipe, etc.) on my 1999.5 A4. I went with the Unitronic chip, which required a 3'' MAF sensor.

I failed the emissions test at DMV. Here are the explanations that I got for the failure: catalytic not ready, oxygen sensors not ready and evaporative system not ready. I'm trying to trouble shoot why these items failed and resolve the issues.

I had to make a custom intake system that eliminated some of the hoses that are normally plumed back into the intake system. I think this might be accounting for the evap failure. Any ideas here?

Since the ATP system came with a 3’’ test pipe I installed a 3’’ cat under the car and extended the 02 sensor in order to be emissions complaint. However, I ended up failing for both the cat and the 02 sensor. shouldn't this have worked?

Has anyone been able to make their big turbo kit street legal. Or have any idea of how an can fix these issues on my particular application?

Thanks.
Stretch

 

You need it close to stock as possible. Having the evap setup like stock will be a start. Also, your cat is probably to high flowing causing it to throw that code aswell. Unitronic can also program out those codes so you should pass also, talk to your rep about it

 

Agree with everything cincy says above...
I passed with a samco TIP and my stock airbox...
I know of a bunch of people running tantrumwerks/labree/tectonics high flow cats that are setup to run the 02 sensors in the stock places and they do not throw a code...

you should think about getting a HFC, and besides that just get the stock airbox in the car and you should be fine...and if you were wondering, the FMIC is 100% smog legal

sounds like your biggest problem will be your testpipe/HFC setup, they will be looking for the cat on the hotside of the turbo, not under the car....

good luck!

 

Thanks for the great advice guys. I don't think I'd be able to go back to the stock airbox. That would probably through off my tune. I'll plumb all lines from the stock system into the 3'' setup. I'm definitely going to call Unitronic on Monday to sell what can be done with regards to eliminating the codes. Cincy, would DMV get any kind of indication that the ECU is blocking any codes?