i know there is a e85 update at the dealership and they will flash it when i take my truck in for warranty work. i have hp tuners and i dont want it to mess my tune up. does anyone know what is done?

 

Put it back to stock tune, go get the update, then compare the tunes. Put you current tune back into it and see if there is anything from the updated E-85 tune that you could benefit from.

 

sounds good but, i think they change the os. is that going to make a difference.

 

I have a 2007 classic 5.3 flex fule and got the update and they didn't change a thing. The invoice said that they reflashed the computer and did a fuel relearn. I compared it to my stock tune and found no diferances.

 

Changes could have been made to the part of the tune that we don't have access to. I would keep the tune they put in it and just do a cal only flash with your settings.

 

i did not compare the tunes but the last truck i tuned they did change the os. i ust copied the changes to the new os and reflashed it.

 

That sounds about right? What I did was read the new GM tune and added my changes and reflashed. Making changes to the tune that we don't have access to didn't even cross my mind. Now all I gotta do is figure out what AFR to command for the diffrent Stoiches (Dose Stoiches make any sence) in the PE table. I just tuned it for gas up to I think....12% Ethanol.

 

al have you tried to do the rtt in your hp tuners????

 

I did the same to my friends truck.
But I did do a compare, the changes cannot be seen in HPT.
He says it runs noticeably better on gas and e85 now.

 

No I have't tried it. I did see a help file on rtt and it looks bad ***. Dose it require any more credits to get rtt? I'd like to try it out. All I have done so far is tire size, rev limiter, speed limiter, fans for 160 t-stat, trans shift RPM, trans TQ managment, and A/C cut off rmp. and I did change the stoich up to I think 12% ethanol to 14.62. I just got it dualled out the Fri. befor Christmas and I had "another" O2 bung (Thats another story) welded on befor the driver side cat as well. Kroger and GM sent me a $20 gift card for E-85 and I just used it so I want to make sure all of the extra ethanol is out befor I tune it with the WB. I guess with the rtt you will need to reset your VE histogram after you make your changes??? Or can you just play with the VE table a bit and see if the cells are getting closer to zero. I have a stock MAF on the truck, but not on the Z28. I wounder if rtt would make tuning the MAF and VE that much easier?