Switched to E85, changed stoich value and VE way off?

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08-19-2013
MustangPunk

Switched to E85, changed stoich value and VE way off?

I drive a turbo'd 2006 Silverado WT 4.8L non flex fuel. I filled up with e85 last night, with only a few gallons of gasoline left in the tank, I drove for a few minutes to maybe get some of the gas outta the rails. Then uploaded a tune, I changed the values in all cells of the stoich table to 9.8 for e85. It started rough but I drove for a little while (10 miles maybe) and it stayed rich, and I had to take out 20% from the VE to get to lambda while driving. I ended up driving for over 40 minutes. The gas tune was pretty spot on. This morning the cold start was super lean, and just a little lean crusing, man am I confused, I thought all fueling would be adjusted to the change in stoich?
08-19-2013
Eric@HPTuners

Quote:

Originally Posted by MustangPunk

I drive a turbo'd 2006 Silverado WT 4.8L non flex fuel. I filled up with e85 last night, with only a few gallons of gasoline left in the tank, I drove for a few minutes to maybe get some of the gas outta the rails. Then uploaded a tune, I changed the values in all cells of the stoich table to 9.8 for e85. It started rough but I drove for a little while (10 miles maybe) and it stayed rich, and I had to take out 20% from the VE to get to lambda while driving. I ended up driving for over 40 minutes. The gas tune was pretty spot on. This morning the cold start was super lean, and just a little lean crusing, man am I confused, I thought all fueling would be adjusted to the change in stoich?

I have not converted a GM vehicle over to Flex Fuel, but have done a lot of Fords, and the same things happens with them. Re-adjusting the VE table is probably the easy way out. I believe the injector values are probably the reason for this.
08-19-2013
Iam Broke

Check your fuel pressure, E85 requires ~30% more fuel so if your pressure is tanking, the IDC climbs and you are going to need to retune.
08-22-2013
sarg

Did you check the actual percent of ethanol?
08-28-2013
CarsonTech

OP, you can get a "flex fuel sensor" (oem ones work fine) and a gauge/module to display the ethanol content of your gas. Make sure you get one with outputs, so you can log ethanol percentage in HPTuners. I think you could also just use the sensor if you just wanted to pipe the voltage directly to HP Tuners.

http://www.zeitronix.com/Products/ECA/ECA.shtml

https://www.youtube.com/watch?v=wsWZVrdpSRI