lean vs rich.

[jrmybck]

if we are trying to make power by leaning why are we changing injector slope to - numbers and not +

[06MonteSS]

those old 350's teach you nothing??? j/k man...

k.. the slope setting gets your ltft's into the proper range for part-throttle driving and fueling needs... at part-throttle normal driving, your AFR will always be at 14.7... the ecm uses the fuel trims to know how much to compensate the amount of fuel in order to keep the AFR at that stoich value...

by adjusting the slope, you make it so the ecm does not have to correct as much with a swing in the amount of fuel to add or subtract... which results in faster response (throttle) and acceleration, and better mileage - cuz it's not adding in more fuel than it has to, then take it out, then add, then take it out, etc etc in order to stay at the 14.7 AFR...

WOT is different... that has it's own PE (power enrichment) fueling table and AFR settings specifically for WOT... leaning THAT out gives you more power (to an extent) - like with anything, too much can be bad for ya... WOT does not use the LTFT fuel data to adjust it's fueling, since it has it's own separate PE fueling table... HOWEVER - there IS a caveat to that..

if your ltft's are positive, meaning you are lean so the ecm has to add fuel - then the ecm assumes you will be lean at WOT also, so it will add additional fuel on top of that wot/pe fueling table - which you do not want to happen.

so, that is why you need to get your part-throttle fueling ltft's dialed in to be between 0 to -2 before you do any WOT adjustments...

that way, when you go WOT, your ltft's will be 0 or slightly negative... and when your ltft's are 0 to slightly negative, the ecm does not use them for WOT/PE operation...

hope that clears some things up for ya...

[jrmybck]

so now to set my fuel at wot what do i need to do.. and thanx, i understand.. how do i get to 12.8. if thats where i need to be

[06MonteSS]

you'd need to use a wideband to know for sure where you're at... but... predator is close for N/A vehicles....

if you're slope is adjusted to -11% right now... we'll call it -10%... for evenness sake...

so, in the PE settings, adjust those to 1/2 of your slope setting for now... so, adjust all the rpm ranges in the PE settings to -5%....

[jrmybck]

i dont have pe settings.2.xxx are they called something else like fuel wot? should i set wot fuel at -5% to lean, then check afr, which should be 12.5-12.8 correct?

[06MonteSS]

yep...

and yep...