Re-programmed ECM, 87 vs. 91/92 octane

[gavin]

I reprogrammed my ECM with a SuperChips tuner a long while back, like, middle of last summer.. well, recently I realized, my gas mileage hasn't went up any since summer hit. And, I think this is really weird, I get better gas mileage with 87 octane, compared to 91/92 octane, even tho the ECM is reprogrammed. Somewhere along the lines of 4-5 mpg better. This isn't normal, is it?

 

[jimbo74]

in most cases, 87 will yield better mileage as a performance burn or flash using 91/93 is normally setup to increase power, less mileage being a side effect of that....

 

[gavin]

I guess I was just going by all the assumptions that say chipping increases power and gas mileage, lol... oh well. Removed the programming for now to see how the gas mileage is.

 

[jimbo74]

at 87 octane there is less power but less fuel used..... this means better mileage... with a performance burn, it uses more fuel and sets the timing and all that differently

 

[gavin]

yeah, that makes sense.
I guess I should stop believing all the ad's, haha

 

[aldive]

at 87 octane there is less power but less fuel used..... this means better mileage... with a performance burn, it uses more fuel and sets the timing and all that differently

That is simply NOT true.

Take a look at http://www.explorerforum.com/forums/showthread.php?t=127945&highlight=evaluation

and

http://www.explorerforum.com/forums/showthread.php?t=128827&highlight=Computer+tunes+evaluation

 

[gavin]

on a side-note of my re-programmed ECM.... it's not normal, after re-flashing the stock programming, for the RPMs to jump up anywhere between 200-400 RPMs for no apparent reason.... almost seems like the TC is slipping, but I don't know...
didn't seem to have this problem until after I switched back to my stock programming..

 

[storlied]

I know this is an old thread, but this is directed toward Gavin anyways..: Where the hell did you find 91 or 92 octane? All we have here is 90 for premium, and I didn't see any higher when I was in atown?? [Which is pretty sad in my opinion..] Were you down in the states by chance?

 

[gavin]

good lord this is an old thread.

at times there has been 91 octane around. Atleast 5 yrs ago when I made this thread I musta found it.

usually just see 90, but have seen 91 at times.

 

[storlied]

I spose since the economy has taken a beating the luxery of 91+ has been limited.