car_ram_rod

Crush your comment about the LTFT's getting hosed up after setting cruise for 30-40 mins. is EXACTLY what I have been seeing with my car (FIC) for 2 years now. I'm glad someone finally posted the same issue...It'll go from 0 to +- 3 to something like 17 after awhile. Reset and I'm good to go as long as I don't cruise...not certain if it has to do with setting the cruise control or actually just cruising...Sorry for posting this here ScionFred...but there is something else besides fuel trims hosing us here

paul_dezod

Guys, this is normal. The stock ECU is on a long term mission to correct the values in closed loop to 100%. The longer you drive in one area, the more it learns the correction factor to be more precise. This is why taking into account LTFT and STFT are essential.

crush02342002

iTrader: (2)

Paul I understand that and tuned accordingly. I think I get where you are comeing from Paul but this issue is slightly different than having off stft turn into ltft's or a load change that pushes you to a different part of your fuel map that may be off causing high fuel trims. Atleast what im talking about is running the car for a couple of days with fantastic fuel trims at various loads and go out one day and the car has sudden high fuel trims through all loads for the entire day, only to return to "normal" the next.

for example...I start my car in the morning to go to work and let idle for a min, ltft -8 stft+-2 (to be expected on a cold engine). I get on the freeway and ltft eventually changes to -5 to -4 and cruising at 65mph, 5miles before I exit sudden ltft of -40 to -45 causing the car to really go to hell quick. stft stays fairly mild (+-4) while this is happening and still at 65mph though I am forced to let off the throttle. I never seen the stft change and if it had I would have felt the car go to crap. ltft will not change from -40 until the car cools down fully.

eventually fuel trims normalized for a few days and a new problem came up. Atleast once a day I would get stuck in open loop, I could shut the car off, restart, and it would resume closed loop operation for a few min then back to open loop.

So im thinking short (remember me talking to you about it?) so I disconnected the o2 lead for the fic and havnt had that issue come back but now that random ltft problem comes back after a few days.

now im thinking its primary o2 so when that -40ltft pop'd up on me one day I jumped out of the car and unpluged the primary o2 sensor to see what would happen to the afr's. Of course it runs pig rich when i do that which makes perfect sense to me, car is running rich and the o2 sensor is sensing that so the ecu is pulling fuel. But why is it so random and not doing this at a specific load or condition. Only God knows how many hours I spent trying to tune this thing out, Id guess every day on my way to work for a good month.

So I went back to the basics...full boost leak test, new tune from scratch and different tuning stratagy, clean and regap plugs, replace maf sensor o-ring and reseat it, replace resistors and check all wireing for pnp harness, clear fuel trims.
I did find some good boost leaks too...lol...20psi will do that when your last boost leak test was done at 12psi.

All that helped but not cleared up...still have a random large ltft pop up however the whole issue has mutated a bit but still similar. still a long way from where I want it and im still working on it (dont have much of a choice cause Im too damn poor for anything else...lmao).

car_ram_rod

yeah i'm almost positive my stft and ltft do not do anything out of the ordinary. When this happens and I go into open loop my car gets pig rich..9 to 10 AFR Literally goes slower when I get on the gas...it should not effect open loop so much. It's been a long time since I checked again on this issue, but if I recall the LTFT is not more than +-3 and stft near 0 when this happens. I'll check again next time I go on a long trip.

ScionFred

iTrader: (1)

^^^ I had the exact same thing happen to me several times with the FIC. I never went anywhere without my scan tool connected and usually logging so it was pretty obvious when my my fuel trims suddenly went haywire. It seemed to me that the FIC simply stopped adjusting the fuel delivery so that there was no correction for the larger injs.

Another possibility might be a stuck MAP sensor. I don't trust the tiny MAP sensor in the FIC. I've never seen a car use a tiny $5 MAP sensor like that and the only thing I'd trust it for is as a simple boost switch where accuracy isn't quite as critical.

ScionFred

iTrader: (1)

I may be calling you about this. I'm totally satisfied with how my car runs now at 6 psi but I recently tested at 7 psi and it was obvious that I either need a piggyback or a return fuel system and FPR to run more than 6 psi on my setup.

paul_dezod

Chris, one thing you have to remember when this occurs. THERE ARE differences and the FIC has no control over some of the variables that Toyota has in place. The FIC may indirectly alter some of those trims and such because of the way it controls fuel.

For example, the main differences that changed on your ride example are coolant temp and Intake Air Temp.

Coolant temp is probably pretty close to ambient temp when you start. Of course it's going to get warmer and run to about 190ish. You have no way of controlling any fuel or ignition trimming when she gets that warm or excessively warm. Same with spark. No control their either.

Air intake temp is greatly effected as well on this drive scenario. It starts out like coolant temp (close to ambient), but depending on turbo efficiency, ambient air, IC efficiency and MAF location, you can record IATs of up to 165F. The fuel requirements there are different from 80F.

crush02342002

iTrader: (2)

Thats fully understandable however this problem is not consistent though its not without reason that I have a sensor thats damaged. I havnt experianced this kind of condition in the past 4years tuning the fic hence why im scratching my head.

ScionFred

iTrader: (1)

My money is on the FIC. Try another one if at all possible.

crush02342002

iTrader: (2)

That is one thing I havnt tried but thought about, just didn't have the chance as of yet.