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Fmu Re-programming

99greysierra

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99greysierra Enthusiast

99greysierra

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Posted

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 Senior Enthusiast

redvett

Posted
Posted

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 Senior Enthusiast

redvett

Posted
Posted

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 Enthusiast

99greysierra

Posted
  • Author
Posted
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 Senior Enthusiast

95Sierra2500

Posted
Posted

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 Enthusiast

Texsrt4

Posted
Posted

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 Senior Enthusiast

redvett

Posted
Posted
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.

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