sbrown99TA

Is there an easy formula for scaled the PE table to change WOT fueling accurately? Like my car is at 11.8:1 right now and I want to take it to 12.5. I can kind of guess it in the ballpark, but I know there's got to be an easy formula to do it as well. Thanks.

bomax

iTrader: (3)

I am interested as well.

Black Blown 02

11.8 divided by 12.5 = .944

Divide your pe by .944 in the rpm range you want to change.

red ws6 99

AFR = 14.7/P.E. This assumes your IFR table is correct throughout the range (cruise and wot) and that maf is untouched and your ltrims are zero or negitve. With a wideband you can really dial in the IFR then you don't have to put in goofy numbers for PE. Once I got the IFR set my AFR at WOT stays within 3% of the programmed value.

Gary

bomax

iTrader: (3)

How do you go about dialing in the IFR properly? I just scaled it by 90%.

red ws6 99

I log map, ltrims, rpm, wideband AFR. Idle and cruise I run it a little rich -7% Ltrims. I look a the Ltrims and wideband and adjust the IFR table to keep them negative. I have a turbo car with boost referenced fuel pressure so theoritcally I should not have to change any of the IFR cells that you would be in boost. For me thats anything above 80 kpa (atmospheric pressure because I am at 4200 ft). My combination of 50 lb injectors, walbro 340 and crappy aeromotive regulator does not quite do that. So I use the wideband to adjust the IFR (boost region only) until the AFR is what I want. So I will change the PE table to get a 12.5 AFR. I then do some WOT passes ( not on a dyno), change the IFR until my wideband AFR is 12.5. Now I can change my PE table to say 12.7 (PE = 1.157) and the wideband will show the AFR of 12.7. If you change anything to much in the car (fuel, air, spark) related the IFR table will have to be tweaked. I prefer to change the IFR table instead of the PE. To me PE should always be 14.7/PE = AFR with some correction from the PE vs Temp tables. That probably made very little sense, but its one of those days.

Gary