Just got my 3865, and I was wondering how bad it would be to run the performance tune with 87 octane? The gas stations around here offer 89 and 93 octane, if I can't run 87, how about 89?

 

why dont you just tune it with the 87 tune

 

You're probably going to get a lot of pinging trying to run 87 with the 91 tune. The tune is meant for 91, run that or higher, meaning use the 93. If you don't want to spend the money on gas, then run the 87 Tune. You wouldn't get as much of the power gains anyway running the 87 with that 91 tune, and it's not good for the truck.

 

yea for the tunes each one just means u gotta run a minimum of that grade fuel for said tune, u could run 93octane on the 87 tune but dont go down

 

The 87 tune is pretty damn good, go with that unless you put in some higher octane fuel.

 

I cant realt tell the diffrence between the 2 to tell you the truth

 

Oh I read the 87 tune description in the manual as being meant for cars that need premium can run on 87. But it's really just a lesser 91 tune?

 

yeai read that too but its still a big diffrence and you can set pretty much everything the same as you can with the 91 tune. But if you wana c go buy a quarter tank of 93 and set it to that tune and run it for about 100 miles, then put 87 in it and set it for the 87 tune and do the same thing.

 

So what options would make it like the 91 tune?

 

Make sure you drive the truck 30-60 miles before judging the performance. The computer needs to learn the new tune.

If you really want to test it out, your tuner has the ability to show what the knock sensors are reading and what degree your knock retard is set at. Even on 93, I still get some knock retard of .5-1.5 degrees if the engine isnt warmed up or if I push it really hard.