WOW...what a MPG improvement!!!!
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Joined: Apr 2006
Posts: 7,253
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RE: WOW...what a MPG improvement!!!!
my compression is fine, checked that already.truck runs great and is actually faster than my buddies identical 06 h3. I pull him from the line and in 1/4 mile strip I beat him by at least 5 lenghts every time. I know the problem is in my PCM tune, somehow someway a tech at the dealership had to be playing with it....but they keep telling me that it because I'm running 35's, even though I was getting 11 mpg with the stock base 265's. Last dealership told me they can't reflash the pcm to stock....technology isn't available yet for the h3....I didn't tell him I was a gm tech...just laughed in his face. I'm going to send it out to pcmforless.com and have tehm look at it and correct. Pretty sad that a I5 is getting worse mileage than a worked 350 SB would get.
I am thinking that something in the cooling system culd be bad, causing the truck to run constant coolant so the motor runs like it is always cold...which burns more fuel. Kinda like having the choke open all the time on a carb motor.
I am thinking that something in the cooling system culd be bad, causing the truck to run constant coolant so the motor runs like it is always cold...which burns more fuel. Kinda like having the choke open all the time on a carb motor.
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Joined: Jul 2006
Posts: 6,692
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RE: WOW...what a MPG improvement!!!!
ORIGINAL: jbnjc123
Since ours was new in Nov.we have never gotten better than 13 mpg. I don't know what you are doing to get 20+. I wonder why there is such a difference? I have been very unhappy with this since I have gotten the H3. If I would have known this I would have gotten the H2. I wonder if elevation would have anything to do with it, but it is fuel injected so really that should have no effect.
Since ours was new in Nov.we have never gotten better than 13 mpg. I don't know what you are doing to get 20+. I wonder why there is such a difference? I have been very unhappy with this since I have gotten the H3. If I would have known this I would have gotten the H2. I wonder if elevation would have anything to do with it, but it is fuel injected so really that should have no effect.
I'm actualy thinking about removing my big clunker light bar. That will definitely increase my mileage.
Joined: Aug 2006
Posts: 82
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RE: WOW...what a MPG improvement!!!!
ORIGINAL: importkiller
my compression is fine, checked that already.truck runs great and is actually faster than my buddies identical 06 h3. I pull him from the line and in 1/4 mile strip I beat him by at least 5 lenghts every time. I know the problem is in my PCM tune, somehow someway a tech at the dealership had to be playing with it....but they keep telling me that it because I'm running 35's, even though I was getting 11 mpg with the stock base 265's. Last dealership told me they can't reflash the pcm to stock....technology isn't available yet for the h3....I didn't tell him I was a gm tech...just laughed in his face. I'm going to send it out to pcmforless.com and have tehm look at it and correct. Pretty sad that a I5 is getting worse mileage than a worked 350 SB would get.
I am thinking that something in the cooling system culd be bad, causing the truck to run constant coolant so the motor runs like it is always cold...which burns more fuel. Kinda like having the choke open all the time on a carb motor.
my compression is fine, checked that already.truck runs great and is actually faster than my buddies identical 06 h3. I pull him from the line and in 1/4 mile strip I beat him by at least 5 lenghts every time. I know the problem is in my PCM tune, somehow someway a tech at the dealership had to be playing with it....but they keep telling me that it because I'm running 35's, even though I was getting 11 mpg with the stock base 265's. Last dealership told me they can't reflash the pcm to stock....technology isn't available yet for the h3....I didn't tell him I was a gm tech...just laughed in his face. I'm going to send it out to pcmforless.com and have tehm look at it and correct. Pretty sad that a I5 is getting worse mileage than a worked 350 SB would get.
I am thinking that something in the cooling system culd be bad, causing the truck to run constant coolant so the motor runs like it is always cold...which burns more fuel. Kinda like having the choke open all the time on a carb motor.
Thread Starter
Joined: Apr 2006
Posts: 7,253
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RE: WOW...what a MPG improvement!!!!
my wifes drives it to work in the am...I drive it in the pm. Until I get my truck in 15 hours we are a 1 car household....not including my JGC but thats in the rebuild faze still.
Joined: Oct 2006
Posts: 532
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RE: WOW...what a MPG improvement!!!!
Buddy, this MPG problem is really bad.[:@]
Why don't you try to put some sugar in your gas tank and find out if your engine is less thirsty whith a 'sweet' gas hmmm?
Another idea could be that you become 'buddy-buddy' with some koweiti oil producer (after all, you guys saved their butts back in '91) and ask him to send you half a VLCC at a discount price.
Sorry, Import I could not resist[&:][8D]
Why don't you try to put some sugar in your gas tank and find out if your engine is less thirsty whith a 'sweet' gas hmmm?
Another idea could be that you become 'buddy-buddy' with some koweiti oil producer (after all, you guys saved their butts back in '91) and ask him to send you half a VLCC at a discount price.
Sorry, Import I could not resist[&:][8D]
Joined: Jan 2006
Posts: 960
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RE: WOW...what a MPG improvement!!!!
IK have you thought about putting stock sized tires on it, driving it for a couple of tanks, and taking it back to the dealership to show them it gets poor fuel economy on it's own? I'm sure a local tire shop would have some used tires you could get for cheap just for the experiment.
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Joined: Feb 2007
Posts: 48
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RE: WOW...what a MPG improvement!!!!
I just filled up on Sunday, and I had driven half city half highway. Now, to credit the Hummer a bit, it's been nasty cold out here (-20'C to -40'C ish), so I think that may have contributed a bit.
This last tank, I put in 76.74 litres (20.30 US Gal, or 16.903 UK Gal). I travelled 404 KM (251 Miles).
That makes my mileage 12.36 US MPG, or 14.85 UK MPG.
All stock on my H3.
This last tank, I put in 76.74 litres (20.30 US Gal, or 16.903 UK Gal). I travelled 404 KM (251 Miles).
That makes my mileage 12.36 US MPG, or 14.85 UK MPG.
All stock on my H3.