Thread: Running e85 on stock fuel system

Isn't the tune as simple as adjusting the stoich. reference in the cruise tables, and then changing the PE target AFRs as well for the E85?? Wondering if I could pick up injectors, a stock pump rewire, and tweak as few as 2 or 3 tables in my tune and run full E85 without any issues.

Originally Posted by 97AutoXVette

Isn't the tune as simple as adjusting the stoich. reference in the cruise tables, and then changing the PE target AFRs as well for the E85?? Wondering if I could pick up injectors, a stock pump rewire, and tweak as few as 2 or 3 tables in my tune and run full E85 without any issues.

You completely can. I picked up a set of 60's used cheap, bolted them in. No need to change any target AFR's, Stoich for all fuels = Lambda 1 it doesnt matter if its E85 or gasoline the O2 sensor doesnt know the difference. For instance running E85 with a wideband setup for gasoline, when it is showing 14.7 you are actually at E85 stoich of 9.76 or lambda 1 all the way around. The gauge is just converting lambda 1 from the sensor to AFR so you have something relatable to read on the gauge. Your stock narrowband works the same way. AFR is just a way to read stoich for different fuels.

Either way all I needed to do is change the injector tables from stock to 60's then the 30% for e85. Ran the tank dry with the pump on and a fuel line off then filled with E85. Fired right up with no other changes, no pump, no rewire, no injector o-rings, not even a filter change, only took 20 minutes. After that I set the timing from stock to 22* and dropped from my 3.4" pulley to my 3.1" picked up probably 30 hp.

Originally Posted by Anthony Smith

You completely can. I picked up a set of 60's used cheap, bolted them in. No need to change any target AFR's, Stoich for all fuels = Lambda 1 it doesnt matter if its E85 or gasoline the O2 sensor doesnt know the difference. For instance running E85 with a wideband setup for gasoline, when it is showing 14.7 you are actually at E85 stoich of 9.76 or lambda 1 all the way around. The gauge is just converting lambda 1 from the sensor to AFR so you have something relatable to read on the gauge. Your stock narrowband works the same way. AFR is just a way to read stoich for different fuels.

Either way all I needed to do is change the injector tables from stock to 60's then the 30% for e85. Ran the tank dry with the pump on and a fuel line off then filled with E85. Fired right up with no other changes, no pump, no rewire, no injector o-rings, not even a filter change, only took 20 minutes. After that I set the timing from stock to 22* and dropped from my 3.4" pulley to my 3.1" picked up probably 30 hp.

Excellent info and detail. Thanks!! Where exactly is the injector table?? Maybe I just have to jump back into the tune this evening and take a look. I also understand what you're saying about the wideband and AFRs, Lambda = 1, etc. That makes sense.. Does the computer always target lambda = 1, and then target a percentage of lambda based on what the PE table/mode is targeting? (when you are on the throttle enough to enter PE mode).