Posted: Sun May 20, 2007 10:39 am
Thanks! I think I finally have it. Ultimately, I want to lean the car a bit more than the tune allows, being at 6700'. Will check the readings and go from there.06MonteSS wrote:no... if your ltft's are positive, you bring it down and get it inline by going negative on injector slope. If you go more positive on slope as you mentioned in your post, you will be making the car more lean... going negative on slope makes it more rich.Whiterock1 wrote:So, we ideally want a LTFT of zero, and if it is positive, bring it in by going positive roughly the same % on the injector slope. What exactly is the value of zero? I assume an AFR of 13 or so? Does this vary by car? ('06 Vette, 7194 in my case) Are the nominal values in the ECU the same in all cars, or do they vary in some range? Is it possible to have a car that already has values of zero or negative? Inquiring minds...
Mike
If your ltft's are negative, that means your car is running rich and the ECM is subtracting that much fuel.
If your ltft's are positive, that means your car is running lean and the ECM is adding that much fuel.
If you go negative on injector slope, it tells the ECM that your injectors are smaller and to spray more fuel.
If you go positive on injector slope, it tells the ECM that your injectors are bigger and to spray less fuel.
At normal cruise/driving, the AFR will always be stoich at 14.75 - since the ECM constantly adjusts the fueling to keep it at this value - that's what the fuel trims are for.
