SATAN

iTrader: (2)

Ok, so everyone knows that E85 requires roughly 30% more fuel depending on conditions.

That being said, my question is...
When you change your injector size in HP Tuners or EFI live for running e85, do you say that the injector is 30% smaller than it really is, thus tricking the computer to deliver 30% more fuel everywhere right off the bat? Or do you tell the computer that the injectors are the correct size and then adjust your entire VE table to run 30% more fuel?

I know that you have to go into your VE table and tune anyways, and that it is not going to be 30% more in every cell, but just wondering what route you guys take when you put the injector size in your PCM for use with E85.

Sarg

iTrader: (6)

Think a lot of people just adjust the stoich value. On cars that don't have that, I have just adjusted the injectors 30-35 percent smaller.

soundengineer

iTrader: (16)

you cant just change injector size...
and changing stoic values just change the "reported" AFR...nothing else

you will need a full retune of the VE and MAF tables for E85
you need to keep the proper Injector Values in your tune to get injector pulse widths correct to have optimal driveability and throttle response

in general, you need 30-40% more fuel with E85. to accomplish the same power results with your car...

Sarg

iTrader: (6)

Of course, but it does give you a starting point. But according to another thread with someone running E98, when they changed the stoich value it automatically added the extra needed fuel. Not sure which gm ecu it was, but that is what she reported. I can't remember which board it was, here or hptuner forums. I have yet to try it personally.

kenp

iTrader: (9)

You do not change the injector values unless you change injectors. You do change the stoich value (B3601) to reflect the value needed to achieve theoretical stoich with the fuel you are using.

If you do not change the stoich value you can get to where you need to be with higher than actual VE table values, but why not do it riight?

I think stoich for E85 is 9.86.

Sarg

iTrader: (6)

Depending on the ecu. Not sure what the op is planning to run, but some ecus do not have the stoich value that can be changed. In those cases, I have found it best to change the injector value for a global modification and then use the VE or maf table to dial it in the rest of the way.

There is a thread on hptuner:

http://www.hptuners.com/forum/showthread.php?t=36343&highlight=E98

The person in that thread tried it both ways and had about the same results. She ended up just adjusting the stoich value which I guess seems to be the "more correct" way of doing it. Apparently this will make a global change in fueling for you so that you can leave the injectors scaled correctly.

2TR

You don't change your injector size in the tune unless your REALLY changed injectors. Change your stoich value to 9.765 for E85.

Sarg

iTrader: (6)

depending on the ecu. Some do not have a stoich value in them.

NicD

iTrader: (7)

Changing your injector size or the stoich AFR table accomplishes the same exact thing, it's a global fuel multiplier. Anybody who says otherwise reads the internet too much and very apparently hasn't done it. The one thing that you do NOT do is scale your VE by 30% to accomplish this as that changes your load, timing, etc. You should only have to make VERY minor adjustments to the VE/MAF afterwards.