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Hello, 2005 GMC
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popfuel Offline
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Post: #1
Hello, 2005 GMC
Hi to all -- Very interesting site, first time post. I have a 2005 GMC 1500 4x4 4.8L gas, 3.42 gear, reg cab, auto trans, 32,300 miles that I purchased with 29,500 miles from a good friend. This vehicle always did 14.5 MPG since new at best according to my friend and my fuel figures, in all weather conditions (N.E. Ohio) -5 to 90 deg F. in city driving. Maybe 17 mpg highway using 87 octane only. My goal is to increase MPG at city driving speeds not to exceed 45- 50 MPH. I also purchased from my friend a "Max MicroTuner" model 2714. My friend used this tuner for "performance mode" for a while but returned computer to stock settings. Using this tuner I changed computer to "87 octane mode" or economy. MPG had an honest increase to 17.4 MPG city driving. Still under test, I reduced all shift points by about 3-4 MPH and see not over 1800 RPM in any gear to reach 40 MPH. This of course is not using jack rabbit starts but driving for economy. I'll keep you posted on any increase. A PCV jar was installed showing no gains but may in long run help to keep engine clean. I intend to install "drilled spark plugs" and "HHO system with double helix type plates" and dual EFIE from Mike. The challenge is fooling the OBD II computer, from what I've read its smart,smart,smart. I'll keep you posted.
05-03-2008 07:13 AM
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mike Offline
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RE: Hello, 2005 GMC
Hi popfuel, and welcome to the forum.

I'm interested int that MicroTuner. Can you adjust settings such as air/fuel ratio with that thing? Or just select from the factory designed presets (most of which are to get more HP and less fuel economy)? I guess if you could dial in the AFR, you wouldn't need the efie. But 3 mpg is still pretty significant by itself.

Please keep us posted on your progress.

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05-03-2008 09:29 AM
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retmil46 Offline
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RE: Hello, 2005 GMC
Got a similar Superchips tuner for my father's '98 F150 5.4 L. While it does let you change shift points, as far as tuning the engine you're stuck with 3 or 4 generic overall tunes - ie, 87 Octane, Towing Performance.

The PCV jar will at least keep the oil vapor being carried over with the blowby gases from getting sucked into the intake manifold and burned in the engine, forming carbon and gunky deposits in the cylinders and on the valves. I used a similar device on the gasser Subaru I used to have, called a Condensator - captured quite a bit of oil that otherwise would have been burned in the engine, but as in your case, didn't see any real effect as far as fuel mileage.

Mitchell Oates
Mooresville NC
'87 MB 300D Turbodiesel
'05 Jeep Liberty CRD (Common Rail Diesel)
05-03-2008 10:59 AM
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popfuel Offline
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RE: Hello, 2005 GMC
mike Wrote:Hi popfuel, and welcome to the forum.

I'm interested int that MicroTuner. Can you adjust settings such as air/fuel ratio with that thing? Or just select from the factory designed presets (most of which are to get more HP and less fuel economy)? I guess if you could dial in the AFR, you wouldn't need the efie. But 3 mpg is still pretty significant by itself.

Please keep us posted on your progress.

Mike, I just received EFIE -- very good service Thank You.
As to tuner, its made by "Superchips" Has three settings- Towing, Performance and 87 octane. Within these choices you can also adjust shift points up or down, shift pressure, Rev limiter (no clue), tire height, rear gear ratio and electric fan turn on temp. Will read and clear trouble codes also. Never used a tuner before buying this truck. Only good to program one vehicle as it downloads factory info and stores it. You can restore factory info that you saved. About all I know about these except around $400+ and some newer ones can be upgraded from your home computer. I drove 1989 Astro Van I purchased new and an thinking of putting HHO system and related EFIE on it because older OBD computer maybe easier to fool.
05-03-2008 01:04 PM
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popfuel Offline
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RE: Hello, 2005 GMC
retmil46 Wrote:Got a similar Superchips tuner for my father's '98 F150 5.4 L. While it does let you change shift points, as far as tuning the engine you're stuck with 3 or 4 generic overall tunes - ie, 87 Octane, Towing Performance.

The PCV jar will at least keep the oil vapor being carried over with the blowby gases from getting sucked into the intake manifold and burned in the engine, forming carbon and gunky deposits in the cylinders and on the valves. I used a similar device on the gasser Subaru I used to have, called a Condensator - captured quite a bit of oil that otherwise would have been burned in the engine, but as in your case, didn't see any real effect as far as fuel mileage.

Hi retmil46
Changed engine oil today and gave PCV jar a good look. Condensed, as you pointed out some oil. No more than 6-10 drops in say 200-400 miles. Long - long - long term should keep engine clean. Also this oil is not in combustion gases and in addition to your description should keep O2 sensors cleaner. This small amount of oil was very clean looking. This vehicle had oil changed every 3,000 miles since new.
05-03-2008 01:22 PM
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popfuel Offline
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RE: Hello, 2005 GMC
[I reduced all shift points by about 3-4 MPH and see not over 1800 RPM in any gear to reach 40 MPH. This of course is not using jack rabbit starts but driving for economy. I'll keep you posted on any increase]


With shift points lowered I get 16.9 to 17.4 mpg city driving. Found O2 sensor wires and confirmed voltages both banks for a base line. EFIE not installed as yet. Still working on HHO generator. Will keep you posted.
05-17-2008 04:22 PM
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