RevGTO

iTrader: (12)

Do long term fuel trims function on the basis of O2 sensor feedback alone, or do other calculations figure into the equation? Example: Commanded AFR/IAT/ECT result in fuel trimming?

I'm working on my OLMAF tune and wondering if I should have disabled LTFTs.

Thanks for any help ...

macca_779

Hell yes you should disable LTFT's.
LTFT's are built off STFT averages and then stored for permanent reference. If you don't zero them prior to trying to dial in a MAF or VE. The stored values are still effecting primary fuelling.

ringram

Best to disable LTFT IMO anyway,
They are evil and will come back to rape you sooner or later.

RevGTO

iTrader: (12)

Well, yes, I disabled them when I went full time open loop and ditched my O2 sensors. Just wondering if they were supposed to function even without the O2 sensors.

Thanks guys.

Pavetim

iTrader: (15)

so you can leave your LTFT disabled and it won't hurt anything? Will it still correct for altitude and baro changes with LTFT disabled?

macca_779

Yes. LTFT's are only there to correct for errors. If there are none then they are useless.

Pavetim

iTrader: (15)

But what do you mean by errors? Errors in the tune or errors in say if you drive from florida to colorado?

Mez

iTrader: (1)

Error vs. commanded a/f ratio in your tune.

macca_779

Tune mate

disc0monkey

iTrader: (10)

huh ?

tording99Z28

iTrader: (3)

Errors in your tune. If your tune is spot on and your STFT's are very close to 0 then the LTFT's do nothing and therefore could be left off is what they are saying.

LS1C5Vette

iTrader: (11)

Full time OL huh? Stay on your tune. Not something I would ever do.

Frost

iTrader: (45)

not full time OL, just no LTFTs. STFTs will keep things in check once the car is tuned.

LS1C5Vette

iTrader: (11)

Dammit, I read the 1st post wrong. I agree tho, shut off LTFT.