My AFR'S are confusing the hell outta me and i was wondering if anyone had any ideas about what it could be. My car was road tuned at 26psi with meth, full exhaust, intake, stock turbo, aND kelford 272's. I have a hallman MBC. My idle AFR's are usually 14.5-15.2. and when id step on it my AFRs would go to 11.2-11.3. but it smoked black and smelled terrible, so i decided to try to slowly turn the boost up. I tuned it up a half turn and the afr's were pretty much the same. eventually i got to a turn and a half. the boost went up about 2 pounds. But now when i step on it, my afr's went down to 10.8-11.0. i just dont get why it would get richer with more boost?? wouldnt it get leaner? please let me know your input. thanks.

 

oo ya i have an evo ix

 

Ignore - I'm an idiot.

 

the reason it got richer when you turned up the boost is because the way the car was tuned. whoever tuned the car made the map richer incase the boost was turned up to keep it from being lean. hope that helps

 

The black smoke is from excess amounts of unburned fuel. The fuel map needs to be leaned out up top. Also remember to keep your meth mixture consistent because it can effect your AFRs as well.

 

Yeah that does help thank you. I just don't see why it would still get richer. I can see if it stayed the same, or atleast went +.1-.2. On the leaner side. But I guess that's just how it works lol. Thanks guys.

 

Turning up the boost caused you to reach higher load cells which had richer fuel values than the ones you were previously hitting. This was likely done on purpose by your tuner for 2 reasons: protect the car from an overboost situation caused by some sort of mechanical bug, and protect the car from what you did; turn up the boost without really knowing what would happen. I'm not trying to sound like an ****, but that's just how it is.

If you want to run the car leaner, you need to adjust the fuel map, not turn up the boost. That's just asking for trouble if you aren't tuned ofr the higher level of boost.

 

Thank you. And now I understand. I put it back to where it was so it's safe again. Thanks.

 

11.2-11.3 is slightly rich for peak torque area, so you could lean it out to 11.5-11.7.

FYI though, my car also smokes black a bit when I go WOT, so does my friend's, and so does every other Evo I've seen in the area. It's probably normal considering the amount of fuel Evo's need in order to be able to run 20+ pounds of boost safely without getting crazy EGT's. If you have a test pipe then that could also explain part of the black smoke.

 

True. I don't mind the black smoke at all. It's seems pretty normal for most high horsepower cars, atleast from what I've seen. My old turbo civic used to do that too LOL