Originally Posted by never2muchboost
hmm i could be wrong but as long as your lt adaptive is below 30% i dont think that there is any difference in timing.i never bother tuning for driveablilty unless im using bigger than 750 injectors.there have been instances though where its pretty close and if im pulling 30% at wot i have to drop the fp because timing gets low.the long term is a broad learned value .i try to pay more attention to short term.i havent really noticed any performance differences in driveability by getting the fuel trim close to 0.but i havent spent all that much time tuning for driveability. i think i am gonna try that on the dyno and see if it really does make a difference.either way the adaptive memory has nothing to do with the big turbo stumbles.i spent tons and tons of time when the stumbles first started showing up trying to get rid of them.i thought the same thing at first,and i had noticed that when i log it with a drb it was always when the pcm switched from one cell to another we were getting a lean spike.still got it even when driving it and forcing both cells to match in numbers.vector and aaron were the ones that realized it was the fuel system restriction that was causing the stumbles.since then any of them that have the stumbles ive been removing the bottleneck and the stumbles are gone.we had a 7 million post discussion about it
why would u pay attention to short term fuel trims? they make no differences because they are based on the long term fuel trims
for example -3.0 on short term with a ltft of -9 is -3 on top of the -9
notice that the short term fuel trims like to stay around zero? while long term will jump out into double digits?
the reason id want to get it as close to zero as possible is because it allows the computer to have the leway it was designed to have for daily driving.
doing this will eliminate the stumbles and bogs those that run fuel kits get while daily driving because the car is running the "fuel talbes" in a way that it was designd.
in my experience the range of change in LTFT between teh cells is what causes the stumble, switching in a great ammount from say -17.9 cell one to -4 cell 2 causes the quik glitch
just an experiment, mb not related to it at all.
because the factory fuel table is setup to run a bit richer at idle, one cant just pull a certain map voltage across the board.
doing so will force the computer to over compensaite LTFT therefor affecting cells and transition
(from my experience) in one instance
if im wrong some one point me in the write direction, these are just conclusions i have come to while monitoring LTFT v. STFT
note: i also did the bottle neck fix stumbles were not "all gone" still had an idle stumble when the rpms would de-celerate and come to in idle rpm, the car still had a bog stumble.
erik's(wowguysrt) car does not have the bottle neck fix and does not have "the stumble"
you say you havent spent any time tuning daily driving or seeing what affects LTFT had on teh dyno yet you go on to say you spent so much time trying to figure out what the stumble was caused by. well how can u even say that its not caused by that if u never tuned your long term fuel trims or daily driving???
another point to your post - the more map you pull timing wont go lower heh that would be great, in reality timing gets higher because the timing equation the pcm uses is based on map volage, less boost = more timing. sooo if u pull too much your just going to get more timing (BAD! on big turbo cars) if your timing is being lowerd its the cause of Kock Retard(the ammount pulled from the total timing in degree's to eliminate knock)
that happens when your tune is too aggresive and causing knock