So Ive been troubleshooting this tuning issue for a few weeks now and still havent figured it out. It started prob 3 weeks ago. I street tune the car myself and have it dialed in perfectly when its say 80-85 outside at night. LTFT are within +5/-5 across the board. The problem is when under wot when its over about 90 outside during the day, the car runs pig rich (10 afr across the board). The weird thing is, LTFT are still in line with very minimal STFT even when its up to 100 outside. Ive also verified fuel pressure is not fluctuating based on temp (I have a fuel press gauge in the car). Also for future ref, I have my wideband set to 14.7 stoich, so any references I make will be using gas afr. Whats weird is it only started doing this in the last few weeks, no real changes to anything.

My setup is as follows -

60-1 at 15 psi
E85 - return system at 60 psi base fuel pressure.
Built shortblock (9:1 comp)
dezod intercooler/piping
MAF is AFTER the bov in the charge piping
AEM FIC

So onto the IAT question -

For those of you with a blowthrough MAF, what IAT's are you seeing under boost in say 87-92*F weather?

Whats weird is mine are consistently 95-97 while driving and max at like 100 while under boost. It seems the sensor is working as itll climb to 105 ish while sitting still but it seems like its reading low under boost, which could be causing the pig rich condition when its hot outside.

Thanks for any help, and if your response is ditch the FIC, you're not being helpful and can feel free NOT to post your reply.

 

Im really starting to think it could be the MAF sensor causing my issues (IAT related). Ive done some research and have yet to find ANYONE who has a IAT within 10 deg of ambient under boost.

**EDIT**

When I take the car out for a lunch break around 4 ish (hottest part of the day) Ill log IAT again and well see, if its similar to earlier than maybe Ive found the issue (Not that I want to have to buy a new MAF )

 

Update,

Well does not appear to be an IAT issue - Iat's seem to vary as expected, and Ive also found the issue sometimes also occurs at night (when its cooler). I played with the fuel map under vacuum as there were some parts with higher ltft and got it corrected, however the issue still occurred at random. I also have a tranny issue now, so this has kind of taken the back burner, however once shes back up and running in the next week or two Ill need to address this once again. The 02 sensor is under warranty from Autozone, so Im thinking about going in and getting a replacement. Also thinking about picking up a new maf from the scrapyard for $30. If you guys have any other ideas feel free to shoot them out there.

 

Hey im no longer participating with scionlife.com

But if you would like any help with this issue, please feel free to email me @ Mike@mtuned.net

Im sure we can get this worked out for you!

 

No love for SL anymore? Ill shoot you an email with all the details, copy of the map, and some datalogs.

 

So what are normal IAT's cruising before boost? on a hot day (85-95) degree weather? And what IAT's is everyone seeing under boost?

 

try taking the o2 sensor out, check ur fuel trims against ur psi and dial it in that way and see how u like it.

i dont run the factory o2 sensor, people have flamed me for it but the car runs smooth as if it were na, and im making 296whp in 105degree florida temps, and i have about 5k miles on this setup

 

____, forgot there were multiple threads on this. This turned out to be a short in the wiring / connector to the maf. Discovered this after the issue occurred one night, than i began playing with the wiring/connector to the maf, and suddenly the fuel trims started going back to normal. I went back through and resoldered a new maf sensor connector/pigtail in from a spare wiring harness I had in my garage, than heat shrinked the connections - no problem since.