2008 Trailblazer SS e67 PCM Switching to e85

Hoping for some input on switching from pump gas (93) over to e85 full time, without flex-fuel sensing. Vehicle is a 2008 Trailblazer SS 6.0L, e67 PCM.

It was tuned on 93, and we would like to run e85 full time. Should i expect to have to reduce VVE/MAF by roughly 33%? Or will changing the stoich (from 14.7 to 9.8) setting be all that is required. Or Both?

Also going to 80# 3 bar injectors. With the hard coded injector limit of 63.5 lb/hr, others have suggested I use the method of Doubling Stoich, Halving the IFR, halving the IVT terms to get around this. Also - i have read that this method doesn't work with these computers.

Open to suggestions!

George

Hi George,

I have never done this on that particular ECU, although had done on a E38 about 4-5 weeks ago. I changed the Stoich AFR and it was pretty close, although other things which will need to be taken into account is the flow rate will drop as the fuel density changes. It will also upset other factors such as injector tip temps etc etc. Most can just be offset in the main fuel map/MAF scaling as only minor changes. If automatic, the trans does use this info for torque calculations to aid with correct pressure for shifting. But if you are not miles off then will be fine.

In regard to the hard limit of the injectors. This will change the fact of being able to do the above. I have not had to deal with changing to E85 and having the hard limit (Although have had the hard limit several times). I suggest having a read of this article from Dave Steck of DSX Tuning (Posted on Injector Dynamics website)