Process

Looking for any help for an issue on my LNF.

Car is running lean on acceleration and randomly goes lean at idle. Short term fuel trims are always at least 7-9% positive during acceleration and long term trims are over 10% and will drop sometimes during deceleration. I've noticed a drop in power while in boost as well, but still spools up normally. Clearing the fuel trims result in short term trims being fully pegged at 10%-20% until long terms slowly climb back up.

Modlist:
Dejon intake, dejon hot side piping, ZZP intercooler, and 3 inch turbo back (catless)

Things I've checked/replaced:

New MAF
Both New MAP sensors
New upstream and downstream O2 Sensors
New spark plugs
New VVT Actuator Solenoids
No vaccuum leaks found by using the propane method
Boost leak test has been performed 4 times (found a leaking intercooler end-tank, replacing it did not fix the issue)
Vehicle does not have any exhaust leaks
Fuel pressure (before and after high pressure fuel pump) is in spec and injectors are all firing consistently and at proper pulse widths with no leaks
There is no Knock Retard or bad timing advance
Compression test is in great condition on all 4 cylinders
There are no misfires, DTCs, or otherwise strange symptoms.
The tuner that programmed the custom calibration has confirmed that the tune is not to blame
Charging system and battery tested good
Had a leaking fuel line replaced before this happened, it was spliced in from the center of the car to the fuel tank

Hopefully someone can help me figure this out, thanks!


Any suggestions are welcome and I'll answer every one. Whoever figures this out I'll gladly pay because at this point I'm desperate to fix this. Thanks

NickStarr

The only time my car went lean was cause of my HPFP.
I was in "P0089" low fuel pressure and limp mode.
That's my only opinion, sorry.

umrdyldo

iTrader: (1)

If you are hitting your target pressures and lamda at WOT then I'd suggest retuning the MAF.

You keep saying it's not tune related, but haven't confirmed if retuning the MAF fixes the issue.

As for what has caused this issue, you have done a good job of narrowing things.

If you were really concerned you could always do a compression and leak down test. How do your valves look?

Process

Valves were cleaned not too long ago with a new PCV and IM gasket. The car doesn't hit the commanded lambda at WOT. Im tuned for 12.4 and its around 15 so I don't go WOT until this is fixed

ECaulk

iTrader: (6)

It's the tune. The LNF stays in closed loop even at WOT, hence why you have a moving STFT and LTFT. Get the MAF dialed in better and watch the trims get closer to 0.

Is the STFT shifting more positive during WOT?

Process

Its fairly positive in vaccum but when I go into boost and WOT its just a bit lean. Im concerned with the normal driving being so damn lean and this is a recent issue so I'm unsure of how the tune is the problem. I've had this same tune for 2 years and am just now having issues within the past few months

ECaulk

iTrader: (6)

What pressure did you go to during your boost leak tests? Did you get a leak detector or soapy solution to cover everything and look for bubbles?

If you have hptuners start logging it and try to make an adjustment and see how it reacts.

Process

I went to 28 PSI, IM tuned for 23 PSI. Sprayed down every connection, coupler, vac line, and the intake manifold

Process

Bump,new info found