Quote:
Originally Posted by chiphead
So what does a AFR gauge read on E10 vs straight gas? Does the gauge read richer on E10 if lambda isn't calibrated to E10? Meaning the gauge may read 12.0 AFR, when the actual AFR is about 12.6?
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If the gauge is reading gas scale, you have to know where your stoich numbers are and calibrate it in your head and you need to command the carb or EFI to give you what you want.
Remember the sensor itself doesn't know what you're pumping through the engine, so lambda is always 1 and it delivers a reading based on voltage variance away from 1. You gas scale calibrates from there.
This really only becomes a concern when you're going very far away from gasoline, like all the way to E85 where your stoich numbers are significantly different.
What I do on my FiTech system is to command a couple points richer everywhere and leave it be. Instead of running around 12.8:1 at WOT, I commend closer to 12.5:1 and at idle and cruise I command closer to 14.1:1 instead of 14.6:1.
As with any type of tuning, listen and smell what the engine is telling you. Don't just worry about that number on the wideband. My engine likes around 14 to 14.4:1 at idle and at cruise will happily tolerate close to 15:1. Outside of WOT, it doesn't like to be richer than about 13.6:1 anywhere. This is all with e10. There's very few gasoline only places in Colorado and when you do find it, it's typically lower octane, meant for small engines.