EFIDynoTuning Forum

I've been working on my idle and startup air and I have hot idle pretty well dialed in.

I'm now working on startup adjustments and trying to dial in FN1861.

Random numbers here, lets say I start the car and ISC is low, so IPSIBR increases to add air eventually stabilizing at 0.2.
I know I need to increase the cells in FN1861 table, but not sure how much. Since that table is a multiplier, it's not as simple as adding 0.2. I tried that and overshot. The first couple times I overshot up and down so it either revved high for too long or low for too long. Now I'm creeping the values, but it seems like there could be an easier way to somehow use the IPSIBR value to modify the table in the specific cells.

Is there a rule of thumb for making adjustments to the FN1861 table based on IPSIBR, or is it trial and error?

Set up a histogram to log your idle airmass divided by ipsibr and you'll have a multiplier percentage for the isc multiplier table.

ipsisbr +/- 0.2 is well within limits, its not going to make a difference if you adjust for that or not. Best bet is to just kick it up a little bit and try again later if you'd like. Again though its not going to make any difference.