Tuning larger LT-5 cams - ZR-1 Net Registry Forums

XfireZ51 · 05-29-2011

I've been reviewing the def file for my 92 ZR ($D0A) and I noticed there is a constant for O/L Change Bias v CTS of -13.67%. Coincidently?, the table values in the O/L Change Bias v CTS do not go below -13.67% beginning at 80C on up.
I had set the O/L Change to -11.67% from 80C on up in an attempt to lean out O/L idle. I have a suspicion that anything less or should I say leaner than the Change Bias number prevents the LEARN flag from flipping to ON. At 80C and above with a Change Bias of -13.67, the ECM won't modify the AFR produced by using the appropriate VE table value (RPM x MAP). Makes me wonder if there's a way to run O/L idle. Perhaps setting the O2 idle voltages to the point where the O2 sensor doesn't swing thru the O2 window at idle. So O/L idle and C/L cruise. Hmmm?:huh:

05-29-2011	#7
XfireZ51 Join Date: May 2007 Location: Chicagoland, IL Posts: 9,686	Re: Tuning larger LT-5 cams I've been reviewing the def file for my 92 ZR ($D0A) and I noticed there is a constant for O/L Change Bias v CTS of -13.67%. Coincidently?, the table values in the O/L Change Bias v CTS do not go below -13.67% beginning at 80C on up. I had set the O/L Change to -11.67% from 80C on up in an attempt to lean out O/L idle. I have a suspicion that anything less or should I say leaner than the Change Bias number prevents the LEARN flag from flipping to ON. At 80C and above with a Change Bias of -13.67, the ECM won't modify the AFR produced by using the appropriate VE table value (RPM x MAP). Makes me wonder if there's a way to run O/L idle. Perhaps setting the O2 idle voltages to the point where the O2 sensor doesn't swing thru the O2 window at idle. So O/L idle and C/L cruise. Hmmm?:huh: