High STFT At Idle
 

Hey Guys,

Having some issues with my tune right now and after a few revisions with my tuner the fuel trims at idle are still pretty high (15-20%). Looking for suggestions.

FBM turbo kit. I have looked over all the intake piping and cannot find a leak. Manifold pressure at idle is around 0.32 bar, vacuum at idle is -19 mm/Hg, which from what I've read on here is normal.

The trims look a lot better under light throttle and cruising around, really just having the issue at idle. I'm leaning towards and exhaust leak, but this issue only popped up after I adjusted/tighted up my IC piping right before the throttle body.

Front O2 sensor is relatively new and maf sensor was cleaned recently so I think I can rule those out.

I'm trying to spend as little time laying on my freezing garage floor as I can so any help is appreciated. TIA

https://datazap.me/u/motox16/1212-idle?log=0&data=30

Then maybe you had an intake leak before tightening the IC and you just need now an updated Maf scaling/SD VE scaling(if hybrid SD)

I usually see a bit higher engine load during warm idle, like 0.21 or a bit more at those rpm you are
You having only 0.17,i would just fix the maf scaling, I don't think you have a mechanical problem

Its very possible I had a leak before hand, but I have been working with my tuner since I made these changes. We've done 3 or so revisions since then and my stft's havent really changed at all, which is why I was thinking a hardware problem.

As far as engine load goes I have no idea why it would be different. I am definitely a bit of a noob when it comes to tuning, but I'm trying to learn more. I wouldnt say it was warmed up though, oil temps were only 110F

What I said about engine load, I was meaning that I think the actual maf scaling could be a bit low than needed
In fact STFT is trying to put more fuel

Any idea why my maf voltage jitters around so much? Seems like 1.2-1.35V is a pretty big range to be jumping around in

Doesn't seem so problematic, it always tend to do so to an extend, also turbos could cause a bit of MAF fluttering I guess

Do you have bigger port injectors ? If so check injector latency values


Anothe way round it willbe run 100% direct injection to about 0.4 load in pi\di tables


If that fixes fuel trims at idle once car warm then its likely port injector scaling\latency problem with the bigger injectors