It should be stored in volatile memory and would be set back to defaults of 0% correction when battery power is removed. Another thing to think of when dialing-in a tune using adjustments in fuel pressure or electronic tuning methods (piggyback, etc.) that trick the PCM is that it if you have the car set up how you want it and the PCM losses power it will have to re-learn these variables as well as others such as long term knock retard. For someone really pushing the limits of these tuning methods and putting down a lot of power that could have some not so pleasant results if it ran a little leaner than you expected. It does learn and adjust the short and long term values pretty quick, but you do have to operate in that particular cell for it to adjust fuel trims for that cell.
at what voltage is the tps kicking the pcm into PE mode where none of this applys. also on the lt1 and ls1 pcm's they will pull fuel in PE if they are also pulling fuel in a long term trim, does the srt do that too
My long term trim is way off. If I reset my computer and restart the car it will go rich, 12:1 for about a minute and climb back to 14.7 at idle. Long term shows maxed out trying to lean car out? LIke 30% leaning. What would cause my car to be so rich and need that much fuel takin out? Car runs fine, just wondering why so far off. I am stage 0 w/mods, see my sig. No cat, with spark plug non-fouler on 2nd O2.
I fixed my TPS with the mopar wiring package yesterday, my idle was off like everyone elses. Didn't affect my A/f though. Took to my buddy at the Dodge dealer after fix, still showing long term fuel trim over 20% correction,leaning. YIKES
PS- I thought my NOS fuel solenoid was leaking into the intake so I dissconnected it. NOPE
I fixed my TPS with the mopar wiring package yesterday, my idle was off like everyone elses. Didn't affect my A/f though. Took to my buddy at the Dodge dealer after fix, still showing long term fuel trim over 20% correction,leaning. YIKES
PS- I thought my NOS fuel solenoid was leaking into the intake so I dissconnected it. NOPE
Did you check you fuel preasure?
__________________
-------------------------------------------
Don't argue with an idiot; people watching may not be able to tell the difference.
Soooo how would someone go about trying to tune the trims in closed loop?
It seems that since there are so many different sensors constantly adjusting everything based on load, speed, temps, O2, etc.... that you can't really account for every situation with something like a SAFC? There's just too many variables?
Also do you just drive down the street at a constant rpm & speed looking at the trims. Then go into the piggyback at that rpm range & make your adjustments?
__________________
John Ruckman
- Stage 3 W/ Toys
- AGP WGA, Race FMIC & 3" Intake
- Custom Magnaflow Exhaust & O2
- Eibach Prokit
- B-Woody Traction Bars
- ND Performance Traction Control System See My Ride Here
You've basically got the idea of it. You could try to tune for each cell but there's so many variables that affect the trims and you can only somewhat alter a few of them. The best thing to do is just keep an eye on them to make sure they aren't getting near the end of their adjustment capability. What I mean by that is when long term correction starts to get up over 20% you might see if there's a way you could mechanically or electronically add/remove a little fuel to bring that down closer to 0%.
One of the computer-based OBD-II scan tools that can data log might be the best bet to watch what's going on with the fuel trims. As long as they aren't going from a heavy correction in one cell to mild or no correction in an adjacent cell I wouldn't take drastic steps to only alter the fuel trims. It is something to keep an eye on, but don't put its priority over A/F, EGT's, timing curve, etc. If you're getting some subtle drivability issues it is something to look into.
AutoForums.com is the premier network of enthusiast-owned
enthusiast-operated automotive communities.
We operate more than 100 automotive forums where our users consult peers for shopping information and advice, and share
experiences and opinions as a community.
Linear Mode
