Fmu Re-programming

[99greysierra]

Hi All:

I am new to this forum, so be patient if I'm asking questions that have been covered before. I have a 99 GMC with the 4.8 liter. Since they put 10% ethanol in the darn gas my HWY MPG dropped from 20-21 down to 17.5. At $4 per that hurts !! Is there any way to reprogram the FMU to at least partially compensate for the fuel change ? Thanks in advance for any responses.

[redvett]

FMU???? No such animal on a truck.

You should only drop about 1/2 mpg with 10%.

You should make sure your truck is in top operating condition and then maybe get a tune.

If you put larger tires or larger exhaust and reduced back pressure put bit back to stock first.

[redvett]

FMU???? No such animal on a truck.

You should only drop about 1/2 mpg with 10%.

You should make sure your truck is in top operating condition and then maybe get a tune.

If you put larger tires or larger exhaust and reduced back pressure put bit back to stock first.

[99greysierra]

FMU???? No such animal on a truck.

You should only drop about 1/2 mpg with 10%.

You should make sure your truck is in top operating condition and then maybe get a tune.

If you put larger tires or larger exhaust and reduced back pressure put bit back to stock first.

 

Sorry......whatever manges the fuel delivery system....there must be a way to reprogram for better economy......any suggestions for vendors ? And my truck has the same tires and exhaust as it did before they aded the damn ethanol.

[95Sierra2500]

I hate to say it, but I notice a HUGE drop in mileage when I go to a station that advertises their 10% ethanol crap (a good 2-3 mpg) in EVERY vehicle I own. Even my dad's old truck has dropped from about 11 mpg to 8. Anyone who says you should only see 1/2 mpg drop is dead wrong.

[Texsrt4]

dont you love it. they increase the cost and add ethanol so your mileage drops at the same time. talk about screwing you into the ground

[redvett]

I hate to say it, but I notice a HUGE drop in mileage when I go to a station that advertises their 10% ethanol crap (a good 2-3 mpg) in EVERY vehicle I own. Even my dad's old truck has dropped from about 11 mpg to 8. Anyone who says you should only see 1/2 mpg drop is dead wrong.

 

Since you live in MI as i do you should know that MTBE is banned and 10% ethanol is the only anti knock additive avaliable.