Fuel trims wont move

[domenico_169]

hey guys, well i just put my evoIII16g in and im having a hell of a time tuning my car. i have 550's, and a 190. when i had my small 16g in it was running pretty good, and i had it tuned okay, but that was a while ago. anyways im tuning with a maf translator, and and laptop with TMO. i have a a/f ration gauge, im not using it to tune but i wanna fill you in because when i had it hooked up none of my fuel trims on my laptop would move, but when i unhooked it i get a low fuel trim reading. i get a oxy feedback no matter if its hooked up or not. i dont know what to do, i am using maf version 1.3 and a 3.5 inch mas. is there any reason why i cant get those reading. (well there actually there but they dont move at all, they just stay straight across the line bellow 90.) as soon as i hit full boost it rumbles like im getting too much fuel or something. i dunno. any help would be greatly appreciated.

 

[domenico_169]

wow, no one had a problem like this before? im gonna hook my stuff up on my buddy's talon tommorow and see what happens. ill post it just in case anyone runs into the same problem

 

[domenico_169]

k well i hooked it up on my buddys just now, he has nothing to tune with but here's what i wanna ask. should the fuel trims be fluctuating at all? or should they sit still?

 

[awdrst]

my fuel trims dont move unless i make some fuel changes and even then it takes a while for the changes to happen. The only trim that moves all the time is my o2 trim.

 

[Budget90GST]

Sounds like your A/F gauge is interfering with your laptop connections. Disconnect it while you're tuning then hook it back up when you're done. Low trims should only move while you're idling or moving real slow (mostly idling). Mid and high trims will not move or fluctuate unless the ecu sees enough changes then they will move. It takes quite a bit of driving to change the mid and high trim ( about 15 or so miles for me). Set the base knob and drive her until you see them change then go from there.

 

[domenico_169]

yeah i unhooked that stupid thing, but i will take your advice and drive around for a while. wish it would take so long. thanks alot though.

 

[BoostedTalonTS]

...I JUST had the same problem in my 94!! -Turns out that the new O2 Sensor I just bought was damaged internally some how, and it wasn't setting a CEL, but after swapping my head and a few other things (including an new O2 housing & sensor), I had the same problem... It took me a while to figure it out but it ended up being the new O2 sensor... DAMN Kragen's... They wouldn't accept it for a refund, as it is an "Eletrical Item", so I got a ~$50 paperweight! -The ceramic inside it wasn't even broken! Ah well.

Another thing to remember, is that the Mitsu ECU adjusts the fuel trims according to consistant engine RPMs... The longer the engine is running under the RPMs listed below, the more adjustments the ECU will make in that specific fuel trim. Here is a list of RPM ranges for the different fuel trims:
0-1500 RPM -Low
1500-2500 RPM -Med
2500-3999 RPM -High
4000&up -Whatever you have set on your SAFC

 

[BoostedTalonTS]

OH, one more thing...
About those anoying A/F guages... A while back I noticed that my A/F guage WAS changing my O2 voltage by about 2-4 hundredths of a volt... SIMPLE FIX: Diode iscolate the guage's O2 sensor wire allowing voltage to travel accross the diode, but not back from the guage. -You can wire it with the diode's silver band facing away from the car's O2 sensor wire.

 

[domenico_169]

thanks for the info man. about the rpm thing, i dont have a SAFC. i hope my o2 sensor isnt shot cause i got it from the devil dealer last year. when i use my TMO i get a oxy feedback trim, and my low trim moves. so i think i will try the patience thing as some members have said that it may take upto 15 miles for the fuel trims to change. i dunno, i just hate this... dammit! but im sure ill be real damn happy once it runs good. but for now im at about 10 psi.