87 Vette Owner

I am tuning my '87 vette (165 ECM, $6E, MAF) in 100% open loop. I've been data logging AFR vs MAF voltage to analyze areas that are rich vs areas that are lean.

I started with a stock APYP bin, and in TunerPro RT, there is a table called "Open Loop AFR % Change vs Load". It lists all the Load figures on the left (going from 0 to 256) and the corresponding AFR % change on the right. For very light loads, there is zero percent enrichment added. But, for medium and heavier loads, there is anywhere from 4% to 13% enrichment. What was GM's original intent for this - to ensure a safe, rich mixture in open loop at heavier loads?

Since I am tuning in open loop 100%, should I zero out these open loop enrichment tables and just tune using the MAF tables (voltages) and AFR? I'm thinking these enrichment percents might throw off some of my readings and make it more difficult to get the MAF tables dialed in properly.

Thanks!
Dan

RBob

iTrader: (1)

Adjust the MAF tables so that the WB reported AFR matches the ECMs commanded AFR.

I wouldn't zero out the enrichment tables, 14.7:1 may be a tad lean under heavy throttle.

RBob.

87 Vette Owner

Thanks RBob! In PE mode, (set to engage at 70% TPS), I've tuned the PE enrichment tables by RPM to hit 12.5 - 13.0:1. You're saying when not in PE mode, but at heavier throttle (55% - 69%), with heavier loads, I should still be a little richer than 14.7:1 (hence leaving the tables as is), correct?

RBob

iTrader: (1)

Yes.

RBob.