I've been attempting to get my tune correct for a while, but have been meeting success only to the point of "good enough." I've accomplished a .98 lambda tune on the VE with MAF Failed, then tuned the MAF. I get surging at low throttle and low rpm once the MAF is back on.
Long story short, I have a 5.7L with a 2004 suburban fuel system that supposedly has the 33LB injectors. the part numbers match up, but the data I'm recording implies that they aren't as large as GM suggests in their factory tune for the 2004 suburban. (or my math is wrong)
I'm using the following formulas to try and back calculate the VE from the MAF and VE from the injector pulse width (corrected by the injector offset) and flow rate. I'm using my wide-band o2 (connected to my EGR sensor return) as a correction factor to normalize both equations, but the end result is numbers that are starkly different based on their source.
Using IPW
100*((([50151.254]-.660)+([50152.254]-.660))/2000*4.1640625*14.681*(([2811]*2.375+7.3125)/14.681))/(0.70821*([50030.90]/(287.058*([50011.240]+(([50010.240]-[50011.240])*.1)))))
100*((([bank 1 IPW-offset)+(bank 2 IPW-offset))/2000*Flow rate*Stoich*((EGR*voltage slope+offest)/stoich)/(cylinder volume*(manifold pressure/(dry air constant*(IAT+((ECT-IAT)*Charge temp Bias factor)))))
100*(Metered fuel*ideal stoichiometric and corrected by wideband o2)/(theoretical maximum cylinder charge)
Using MAF
100*(([50040.71]/([50070.56]/60*4)*([2811]*2.375+7.3125)/14.681))/(0.70821*([50030.90]/(287.058*([50011.240]+(([50010.240]-[50011.240])*.1)))))
100*((Mass airflow/rpm/60*4)*(EGR*voltage slope+offest)/stoich))/(cylinder volume*(manifold pressure/(dry air constant*(IAT+((ECT-IAT)*Charge temp Bias factor)))))
100*(Measured airflow corrected by wideband o2)/(theoretical maximum cylinder charge)
The equations are based off of info I've pulled from this forum and many other sources.
Am I barking up the wrong tree?
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