Hello S2KIers,

So after having my greddy kit in for awhile, I had to take off the manifold to put on a better gasket. After I did that, it got rid of a small exhaust leak I had. While driving for a few km's I got the P0139 code, not quite sure what to do here, I cleared the code and have yet to see it reappear. I also noticed my AFR is acting a bit weird, I used to cruise at 14.7, but now it seems to spike to 13.8 to 15.1 and slowly corrects itself. Also at WOT I used to run 11.8, now I'm seeing up to 10.8 AFR.

Any ideas boost geniuses!?

Thanks in advance

 

Not sure what EMS you are using, but sounds to me like:

1. The leak was bigger than you thought.
2. Short term correction is working as it should (AFR 13.8-15.1 cycling)
3. Your system is sealed now, and you are not diluting the AFR to read leaner than it is

Remember, it takes exahust pressure and flow to spin the turbine, typically more pressure than you generate on the intake side. Even a small leak under 10 psi will loose a lot. AND where ever there is a leak, fresh air will be sucked in (yes, it really happens) in small amounts as well- diluting the exhaust AFR.

IF that AFR is real, it's a little too low IMHO, you're just wasting fuel...

 

Thanks for the response!
I'm using flashpro for engine management. Everything in my turbo system is sealed with much better lock nuts. So I'm not too worried about leaks anymore, however I did get my tune probably when there was that tiny leak.

I'm starting to wonder if one of my O2 sensors went bad or is dirty, that's usually what throws the P0139 CEL code I'd assume. That would explain the jumping afr values aswell, but I don't see why they would go so early, my car only has 64,000km's