i need fuel help...

[08chev]

i live in a small midwest town and the highest grade fuel i can get is 92, and thats at a no name discount fuel station... i'm running that right now with the diablo tune and every once in a while i'll show 2-4 kr on my data logger. (08 silverado 5.3 u7194 9rO6) the other name brand stations offer 91 but i thought i should be running 93... can i dump in a few gallons of e85 (105 octane) to bring it up??? any help would be great...!

[animosity242]

First off: Don't put in the E85! Yes, E85 has a high octane rating but there's not as much energy in ethanol as there is in gasoline. Fuel tables have to be calibrated specifically to deal with E85. If you really want to experiment with a higher (but unknown) octane you can try some additives. I experimented once and got an extra +10% timing before knock.

Secondly: That's quite a bit of Knock! You need to narrow down the variables to better help yourself. Like: It shows 3-4KR when shifting from second to third with more than 90% load. Or: It knocks right when I slam the accelerator down.
How often is "every once in a while"?

[Grumpy_Aero_Guy]

best to post a csv log file with some cruise and WOT bursts for folks to look at...

[08chev]

i'll just have run the 87 tune... i've never had good luck with fuel additives and i cant get good fuel... the nearest 93 is 40 miles away...

[06MonteSS]

the "Diablo Tune" for the trucks is made for 91 octane, not 93... so with using 92 octane gas, you should be fine...

when are you seeing the 2-4 kr on the data logger?? is it when just normal driving, or is it when you're getting on it and goin WOT???