Another_User

As the title says, can the addition of positive trims in PE mode be disabled. I have been dealing with some quirky issues where my car runs a lot better with slight positive trims than negative trims. I actually noticed this back in my "MAF translator" days too. The real PITA is that positive trims have a tendency to stick. But if I could disable that...

MNR-0

Yes there is. Its quite simple. Disable LTFT learning in the Fuel Control section of HPT.

Another_User

I know that. I only want it disabled in PE mode. I hate how my really good questions never get addressed. Weak.

gameover

why does your car run better with slight positive trims? tried messing with your O2 sensor switch points to lean the car out with negative trims? It would be an operating system hack to change the PE mode LTFT behavior.

MNR-0

Well I misunderstood your original question. Sorry for trying though. Weak.

Another_User

I have not seen much in the line of changes after changing O2 switch points. My car does seem to run a hair leaner and better with positive trims, plus they don't go so wacky sometimes. Has anybody had any good results changing the switch points? Can it actually make any significant AF ration difference?

WS6FirebirdTA00

iTrader: (33)

yeah this is what i was gonna say, try to alter the o2 switch points so that the desired switch point is higher and at the fuel trim reading you want. then it should zero out but use the same amount of fuel as before when it was running good. that should be with the upper cells in those tables. just figure out how many g/sec you are getting at these points and relate that to the cell and change that cell.

if i didnt sound clear on this let me know, i can get kinda confusing lol

Another_User

Oh, I follow. The real PITA is MAF table changes affect your airflow, so changing one will affect the other. Shouldn't I go lower if I want to go leaner? Have you successfully made O2 switch point changes with useful results? I never could.

WS6FirebirdTA00

iTrader: (33)

the high end is set at about 550-600 as a switch point which means its running on the richer side, prob around 13.9-14.1 AFR or so would be my guess. try to up your numbers, say your trims are +2, i would go up about 20mV on the switch point. if you are in PE i would imagine u would wanna shift cells 8-16 up, i havent done anything to confirm this just lots of reading and stuff, just makes sense to me, but like i said i dont have any proof to back it up

WS6FirebirdTA00

iTrader: (33)

so u want the car to run leaner, hold on let me rethink this lol, ive got a lot going through my head

ok, i get it now, you have + trims and want them to go down because the car runs good now. so u want to lower the switch point like you said. this will make the car inject less fuel to reach the desired setting, leaving it where you are now and running good, sorry i was thinking backwards. so i would drop down the cells 20 instead

Another_User

I don't suppose anybody has tested this out on a wideband O2? It would be really interesting to see if there is a measurable impact on O2 switching point changes.

WS6FirebirdTA00

iTrader: (33)

i had made changes to this just by smoothing, didnt notice anything bad. as long as your above 451 mV your on the rich side of 14.7 so its safe to just go out and test

Another_User

Ok. I'll tinker with the tune some more.