What is the difference between and E85 and an 98 tune?

[Black X]

Just wondering what the difference is between the two tunes?

Reason being is I just had my car tuned and I asked for an E85 tune but then when I looked at the dyno sheet it said the fuel was 98.

 

[Trewman]

Just wondering what the difference is between the two tunes?

Reason being is I just had my car tuned and I asked for an E85 tune but then when I looked at the dyno sheet it said the fuel was 98.

Id say the tuner wasn't aware you had e85 in the tank and just wrote 98. They will just tune the car to suit the present fuel. So I think Im not an expert.

There is 2 separate maps for each fuel type.

 

[revster]

I asked my tuner about an E85 tune. He said don't bother as the quality varies. I had mine tuned with United P100 but my tuner didnt add in any timing advance so I could run 98 if I wanted. The other thing he said was that the Holden ethanol sensor wasn't all that great with mixed fuels and really only worked properly with either full E85 or 98. He said is becomes confused with a mixture.

 

[VS_Pete]

I can feel a PIR4TE coming on.

 

[07GTS]

there are two tables of timing and a 0-100% table of the ethanol ratio for lambda, basically if u tune it to suit 98 petrol on the petrol side and then the e85 ethanol side has its own spark table that is added or subtracted from the petrol table, so as the ethanol percentage is changing from 85 and anywhere to 0 (petrol) it will use the lambda AFR for that percentage and also a sliding scale of timing to suit... so if set up correct u will have no problems with any fuels...