On the question of whether a mail-in flash yields better gas millage, a forum search yields inconsistent reports. Some further reports would be helpful, and perhaps Al, if you could chime in as well?

Also, a post from Al seems to suggest (to me) that perhaps gas millege is worse (post-flash) during non-conservative driving and better (post-flash) during conservative driving (e.g., on the highway).

Thanks.

Ps. Just to save "flamers" the time, I know gas millage is far too **** of a consideration for most evo owners, and perhaps it should be...

 

Flashes only effect open loop operation maps--i.e. foot is being heavy. Most(95%) of your street driving is based on the closed loop maps. Given that(assuming your driving style remains the same) there would be no measuable change in MPG. Period! People how claim a difference have most likely changed thier driving style after getting the flash.

Even the non-flash tuning methods that can effect closed loop operation can't effect it to a noticable MPG change.

I have a dynoflash and it did not change my mileage.

 

I increased my mileage by about 4 mpg by adding the Buschur stage 2. Probably from the better air flow through the open filter and 3in exhaust.

 

Closed loop(02 sesnor feed back) is crusing and idle operation modes the evo sets a constant 14.6 / 1 a/f ratio (by reading back voltage from the 02 sesnor and ajusting the fuel trims - short term and long term) in these phases of operation which entail more highway crusing

Open loop or high load operation is NO feed back and runs off the target a/f maps in the ecu reardless of the actual a/f

Factory goes super rich up top - into the 9 / 1 range

My tune significantly leans out this area of operation to a steady target of approx 11.1 / 1 a/f which would theoetically result in less fuel consumption

Big overlooked factor is that with the reflashed ecu you are making more power so you need more fuel - even though it is at overall effective leaner a/f target

Baically - best way to conserve gas with an evo is to operate as much as you can OFF boost on closed loop

 

Al,
I think I understand, or do I? During your tune you focus primarily on the open loop? And, post-tune fuel consumption during open-loop-use remains about the same (since any gas saved by your leaning out of the a/f is consumed by the greater power output of the engine; i.e., "a wash"?)??? Is that right?

Also, would it be difficult and safe to re-program the "closed loop" program so as to yeild better gas milliage during "grandma driving"? And, if so, would this be something you could do during a custom tune? (And, if you can do it, are there any down sides to altering the fuel economy per the closed loop?) Thanks...

 

i actually gained approx 6mpg (slow driving) not just from the dynoflash but bcuz i only use 101 octane which burns alot slower & cleaner. my avg is at around 9mpg with normal driving...

 

house, you're getting only 9mpg? Holy crap... um, just fyi, I drove on open loop just as much before as I do now, and I have about 1-3 more mpg non-highway... Highway has stayed just about the same.

 

Leaning out closed loop would have detremental effects on engine durability - (extra heat) - and would not yield significant gains

You have the open loop figured out

 

If I drive very carefully I can get my milage up over 22MPG on 91 Chevron. If I reset my ecu my MPG take a dump downward to about 18. If I am not smoking something I believe this change is due to the ECUs learning capacity. These figures are closed loop driving as it is no trick to eat fuel with WOT or high speed drivng. I have never logged fuel consumption with "76" 100 octane since I only feed her that when I am going to "tear it up."