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XfireZ51 · 03-03-2012

A 10% ethanol gasoline blend drops stoich to ~ 14.3:1. That means you need a richer mixture to equal the same energy available from a 100% gasoline mixture. I change the Stoich number in the calibration. The ECM will use that to calc the pulsewidth required to achieve that. So, if I use straight gasoline while leaving the calibration at a 14.3 stoich, in closed loop the BLM will be based on achieving a 14.3 AFR but in fact motor will run slightly rich. There's nothing "hard-wired" about 14.7 AFR. That's why I can manipulate the O2 sensor voltages and basically re-define what the ECM considers a stoich condition.

03-03-2012	#9
XfireZ51 Join Date: May 2007 Location: Chicagoland, IL Posts: 9,685	Re: stoichiometric vs. AF sensors A 10% ethanol gasoline blend drops stoich to ~ 14.3:1. That means you need a richer mixture to equal the same energy available from a 100% gasoline mixture. I change the Stoich number in the calibration. The ECM will use that to calc the pulsewidth required to achieve that. So, if I use straight gasoline while leaving the calibration at a 14.3 stoich, in closed loop the BLM will be based on achieving a 14.3 AFR but in fact motor will run slightly rich. There's nothing "hard-wired" about 14.7 AFR. That's why I can manipulate the O2 sensor voltages and basically re-define what the ECM considers a stoich condition.