I know this subject has been picked apart in the past but I finally got my car back up and running (a year and a half later)with a turbo now. My BPC is set at .0725 now. The car is showing between 12.5 and 13 to 1 AFR on the wideband at idle and part throttle. If I want to scale down the fuel a little leaner across the board, do I raise the BPC number or lower it?

 

Here are the formula for the correct BPC.
So If you want it to go leaner you need to lower the value.


BPW vs EGR
The correct formula is: BPC = 730.75 * (vol of 1 cyl / inj flow in gms per sec)

BPC calc:

BPC = 730.75 * (VOL / RATE)

; VOL = Vol of 1 Cylinder in liters
; RATE = Injector flow in gms/sec
;
; gms/sec = (lbs/hr / 3600) * 453.6

 

Be careful when using that formula. That formula works well with the RR_V14.ecu file and derivatives. It will give a number like 100 or so. It will not give a number like .7025 (big scale difference). It sounds like you are using a non-TunerPro/non-Tunercat editor. That looks more like a Promgrammer number.

 

To use the formula in Tunercat use the editor and change

Edit step size 1
Minimum Table value 0
Maximum table value 255
Scale factor 1

/N.