I know some people and companies have tuned with LTFT and STFT. ( Short and Long Term Fuel Trim)

I have a dashHawk that reads these as well. Can someone explain how these numbers work as far as lean and rich? Also, what values are good and bad?

 

positive trims mean the pcm is having to add fuel to get you back to stoich, negative trims mean the opposite.

 

So as long as it's not like more than 10% the engine is probably doing well. Right?

 

arrggg u should use clear titles without abbreviation.

 

Well when I post LTFT and STFT in the tuning section I want real responses. Those who know what those abreviations are will answer my question. Sorry to ruin your day

 

winna winna

trims are there for a reason. you don't have a speed density car, so this is the maf doin it's job

 

If its +/- 10% thats a lot of fuel it is adding or subtracting. STFT is what the ecu is doing that instant. If any tuning is to be done based off of trims its the LTFT. Have done plenty of tuning on both of my GTO's and Mustang by making adjustments to the LTFT, all with great results. Increased MPG and HP.

 

qft. if your LTFT is varying by 10% something is up

 

you want your LTFT as close to 0% as possible. right now mine is sitting at -10% with a 2.80g/s on the maf and a misfire on the #2 piston probably all related to the same issue.

 

when i got to florida from Atlanta my LTFT went from 0 throughout the band to -8 to -12 throughout the band.....

Figured more air/oxygen in less volume = less fuel during ignition WTF?