LTFT Basic Question
Thread Starter
Joined: Mar 2004
Posts: 10,316
Likes: 6
From: Dayton, OH
LTFT Basic Question Okay...been wondering about this for a while. I'm running a closed loop SD tune, and for right now, my LTFTs are disabled. From what I know, LTFTs are nothing more than averaged STFTs, which are still active. So what good is it to turn them back on? The reason I turned them off was because I didn't want the LTFTs it figured out from the conditions the day before messing with what was going on at the present...good idea? Bad idea? I'm not noticing any bad side-effects. Runs great.
Thread Starter
Joined: Mar 2004
Posts: 10,316
Likes: 6
From: Dayton, OH
I'm just trying to get control over a PCM that has it's grubby little fingers in everything...I hate trying to go through the convoluted process the computer uses to figure out how much fuel needs to be dumped in at any given time.
I've had the LTFTs disabled for a month, and never noticed any problems. Gas mileage is right where it was on my MAF tune, and the power is definitely there according to my SOTP meter...
I've had the LTFTs disabled for a month, and never noticed any problems. Gas mileage is right where it was on my MAF tune, and the power is definitely there according to my SOTP meter...
i tried to tune with STFT's exclusively, and it was too jumpy, i could never get any consistent readings, not only run to run, but also cell to cell. LTFTs are there to prevent these sort of situations, and just know where your engine is at generically speaking.
so far, my trims are -4 to -1, -6 to 2 in extreeme weather, and holding steady since early june, SD or MAF.
so far, my trims are -4 to -1, -6 to 2 in extreeme weather, and holding steady since early june, SD or MAF.
Teching In
Joined: Jun 2005
Posts: 14
Likes: 0
I was wondering the same thing. My STFTs with LTFT off are almost always between -3 and +3. When I turn LTFTs on, all of a sudden I start getting +4s, +6s, even some +8s.
So I raise my whole ve table by say 3-4 to get a negative trend going. But I still get +ve numbers.
So I've just turned my LTFT off and left it off. What could be causing this? Is my VE table still that far out? Can't see how it can be?
So I raise my whole ve table by say 3-4 to get a negative trend going. But I still get +ve numbers.
So I've just turned my LTFT off and left it off. What could be causing this? Is my VE table still that far out? Can't see how it can be?
Teching In
Joined: Oct 2003
Posts: 14
Likes: 0
From: South Florida
STFT represents the small fuel adjustments made to keep the O2 sensors swinging through 14.7:1 A/F. LTFT is derived from STFT. When the limits for the STFT counter range are reached the LTFT counter is incremented/decremented by 1 and the STFT is reset. This occurs in various fuel trim cells, each representing a different load/rpm condition.
HTH,
Cal
HTH,
Cal
for those who dont speak tech talk...what he just said was...
once you STFT go to far for too long..they add or subtract an LTFT...
so LTFT's really should be enabled to keep the tune in check...
The STFT's are constantly adjusting...and so are you LTFT's...
and as conditions change..your fueling needs to keep it at 14.63:1 also change...
STFT and LTFT are your vehicles way to maitain them.
Now if you are running an Open Loop SD Tne...then who cares... but if you are in Closed Loop....you probrbly would be better off with LTFT's enabled.....
Though this is still all just user opinion...cause nobody has any major bad stories to prove it right or wrong.....
once you STFT go to far for too long..they add or subtract an LTFT...
so LTFT's really should be enabled to keep the tune in check...
The STFT's are constantly adjusting...and so are you LTFT's...
and as conditions change..your fueling needs to keep it at 14.63:1 also change...
STFT and LTFT are your vehicles way to maitain them.
Now if you are running an Open Loop SD Tne...then who cares... but if you are in Closed Loop....you probrbly would be better off with LTFT's enabled.....
Though this is still all just user opinion...cause nobody has any major bad stories to prove it right or wrong.....
