Is this normal?Ltft question

[empie1]

Finally got the car put back together and fixed all leaks.It runs pretty good, but i noticed at wot I am getting a little "skip" and the car is running a little rich.At idle my ltft lo is at 8.6%....At wot, the ltft lo is 6.8%, the ltft mid is 9.4% with the tps at 94% and the getting 16 degrees of timing...I believe I need new plug wires, would this be whats effecting the fuel?I have no leaks, perfect timing and good vaccum so Im a little confused.

 

[hediki12]

i just did my evo ecu swap so im working on my trims so lets see if i can help.
1) you dont use trims at wot or 94% throttle. trims are used under "little" load and over 4250rpm tps cant exceed 36% (im looked it up on the close loop map) .
2) how long do you let your car sit so you can log the ltft lo ? its recomended 16 mins (so that you can get 4 4min cycles)
3) drive at about 60mph try to keep speed and tps as constant as you can for again another 16 mins and there is your ltft mid.
4)if ## stft ever go from fluctuating to a dead consistent 0 in a log session u have just entered close loop. ltfm are what the ecu learns.
5) those +f.t's are saying you need more fuel. i dont know what your using for tuning but +-10% is ok but you want to aim for +-5% because fuel trims affects the afr map that on your ecu.

 

[empie1]

I get what ## saying.But on a stock fuel setup...what should my ltft be at idle?

 

[twdorris]

I get what ## saying.But on a stock fuel setup...what should my ltft be at idle?

Somewhere between +/- 5%. We have a complete description of fuel trim operation on our website if you're looking for something to read.

Fuel trims explained

Oh, also, if you're using one of our chips in your ECU, grab our latest V3 application off our downloads page. It'll work fine even with a V1 or V2 ECU. But the advantage is a much nicer application framework and, more specifically related to your question, a CombinedFT log item that's a much nicer way of viewing fuel trims than looking at the individual values. You also get a number of auto-helpers like this one that make dialing in trims trivial and practically automatic.


Thomas Dorris
ECMTuning, Inc.

 

[empie1]

Thanks a lot man.