I have driven for 120 miles with the O2 sensor being used as a reporting instrument only. The voltage sent to the ECU manually is .61VDC max with the engine running under a very lean fuel/air mixture above that point. .42VDC drives it to the rich side with .55VDC giving me the same mileage as the O2 sensor in control. So it would appear that there would not be a large gain in fuel efficiency by playing with the ECU trim alone. For those that are experimenting with alternative fuels, it is important to hide the true air/fuel mix from the ECU, since the addition of hydrogen drives the O2 sensor into the high O2 range causing the ECU to richen the mix, effectively negating any advantage gained. LP Gas or propane drives the O2 sensor to report a very rich condition effectively shutting down the injectors. I will report on anything that may seem note worthy as the project rolls along.

Regards,
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Will Dallas, www.willdallas.us, www.willdallas.org, www.willdallas.com, www.dallasprecision.com 86 245 DL 222K miles, 93 940 260K miles, 88 765 GLE 152K miles