Ok first off I searched and nothing came up for me so I have a question. Right now I have my 87 performance tune on my truck. I still have to update my sct x3s firmware which I'm guessing I need to copy my tunes to my computer and also return my truck back to stock before updating. I am thinking about changing to my 93 performance tune but have never used it plus I can't get 93 octane, best I can get is 91 which I am in high elevation so I know 91 acts like 93. Thing is, since I got my tunes i have only ever tried 1 of the 3 and have also been using 87 instead of 85 octane because justin said I should use what feels better to me. I was wondering how I go from 87 to 93 tune. Do I fill up the truck with 91 and tune it? I live 26 miles away from the nearest gas station that isn't gouging prices. So can I drive with 91 in my truck on an 87 tune or do I have to bring my tuner with me and change it at the gas station? I hate tuning it because I can never get my tire rotations per mile correct. I got lucky last time I tuned it 4yrs ago but never wrote down the number. I bad to tweak the number I found online for that size to get my speedo correct. Any info will help. Thanks in advance.

 

Yes, you can drive it with a higher octane than required for your tune. I too would not want to load a tune anywhere but home as you never know what can go wrong.

 

You can drive with a Octane tune that is lower than the Octane gas that you are running, but not with a Octane tune that is higher than the Octane gas. In other words, you are fine running 93 gas and an 87 tune, but not running 87 gas and a 93 tune.

 

Even at high altitude, I would not run a 93 tune with 91 octane gas without talking to Justin first.

Of course you can use 91 octane with an 87 tune, THAT won't hurt anything.

Why are you going to mess with it? Sounds to me like everything is running fine and you are getting good gas mileage? I'd seriously consider "if it ain't broke don't fix it".

 

Thanks everyone. I was told 85 is fine with an 87 tune in high elevation so I figured it was the same with running 91 with a 93 tune. I will email justin tho. Just fyi I am at above 6000 ft most of the time if not all of it. According to my garmin, my brothers driveway was 6800ft. My house is a little higher than that maybe 6900.

Glc I am only considering it because I am told I have to do the update on my sct x3. I am getting great mileage and power according to my scangauge2. I can play around and get on it all day in the city and then come home and still average over 20 and my scangauge has read 203hp at 6600ft even tho it was 25 degrees outside. I wanted to try the 93 tune since I have to mess with the tuning anyways but also what you said...If it ain't broke. .. Also the biggest problem is my truck likes to try to stall when in neutral after I tune or return to stock. It's fussy for a good 2000 miles I would say. Has done it since new without the tuner but I have helped prevent it by raising the idle rpm to 850 when I got the tuner.

I guess the biggest question is...do I need to update my x3 if I don't plan on changing the tune until I possibly change it to stock whenever I sell it? If not then I will just leave it..

 

Response from justin.

Hye, 91 and 93 are interchangeable as the KS should adjust, you can run 91 on the 87 tune but not the other way. The tunes will be fine at elevation.

 

If it ain't broke, don't fix it - no need to do the update unless you are going to swap tunes.

 

Ive been told by numerous guy on the other forum if i want to run a 93 tune and only have 91 octane to mix in some e85 to bump up the octane. Havent tried it, though

 

You would have to use enough E85 to raise the ethanol percentage significantly. I wouldn't do it - the EB isn't designed for it and the gas mileage will suck. It may trip lean codes.

 

Yeah I'll just leave it then...but the 93 performance tune does make me curious how much more power and if my mpgs would get any better. Btw I also just bought new tires. I got general grabber HTS tires and they are the only ones my size classified as low rolling resistance tires. So far I am noticing the truck using about 10 less horsepower to keep it going 65 than before but not seeing any difference in gas mileage. Scangauge says 65mph is taking mid 50s hp when it was mid 60s. Then again I've had them for 3 weeks with a tire out of balance until yesterday so we will see if that helps.

 

Yea, according to a online calculator on my truck id have to do 4 gallons of E85 and 22 gallon of 91 E10 to get 93 octane. 4 gallons out of a 26 gallon tank doesnt seem to bad.. Doubt i will try it though

http://www.intercepteft.com/calc.html

 

There's no need to do anything with the X3 at all. I've always been told to not even update it unless you absolutely have to, cause all it does it cause problems.

Mine won't connect to my computer and/or the SCT software won't read it, and I need to change my tunes. So maybe that actually requires a software update? I dunno.