anyone try to improve fuel economy?

[Sputnik13]

I love my 2000 4x4 SLT Jimmy, but I'm spending like 400/month on fuel and that's just way too ridiculous...

Has anyone tried mods to try and increase fuel economy? If so what have you done and what sort of improvement have you observed?

[excheezhead]

Originally Posted by Sputnik13

I love my 2000 4x4 SLT Jimmy, but I'm spending like 400/month on fuel and that's just way too ridiculous...

Has anyone tried mods to try and increase fuel economy? If so what have you done and what sort of improvement have you observed?

the only tried and true gas savings trick i know that have real hard evidence results are,

remove lead from right shoe.
buy a geo, but don't let your freinds see you.


seriously, cold air intake (i recommend k&n), and a free flow exhaust(flowmaster cat back is what i used) will make the most noticable difference, but you will use more fuel at first cause you'll hot rod it for a week or 2 cause it sound so much better!! there are more tricks, but just like horse power, they cost money.

[old_master]

Cold air intake systems are counterproductive. When the air is cold, the fuel mixture must be made richer because cold air is more dense than hot air. You HAVE to add more fuel for the engine to run correctly. That's the purpose of a choke and hot air intake system, (tube from exhaust manifold to air cleaner), on older vehicles. The fuel must be vaporized before it will burn efficiently, this is partially accomplished with heat in the intake manifold. Fuel mixes much more completely and easily with warm air. Basically a cold air intake system is nothing more than hype, added weight, and wasted money. Fact, not fiction!

[thadrawr]

[quote=Sputnik13]I love my 2000 4x4 SLT Jimmy, but I'm spending like 400/month on fuel and that's just way too ridiculous.../quote]

I feel for ya man....I kill a tank of gas in about 3 days. It almost makes me think about getting a car when it dies but i dont think i can convince myself to do that unless it has a big v8 and is from the muscle car era.

[excheezhead]

Originally Posted by old_master

Cold air intake systems are counterproductive. When the air is cold, the fuel mixture must be made richer because cold air is more dense than hot air. You HAVE to add more fuel for the engine to run correctly. That's the purpose of a choke and hot air intake system, (tube from exhaust manifold to air cleaner), on older vehicles. The fuel must be vaporized before it will burn efficiently, this is partially accomplished with heat in the intake manifold. Fuel mixes much more completely and easily with warm air. Basically a cold air intake system is nothing more than hype, added weight, and wasted money. Fact, not fiction!

i shall not argue with the master, it would be like taking a knife to a gun fight, all i can offer is data i have seen with my own eyes. the K&N system i use is the FIPK GEN II, which is advertised as "cold air intake" because they are targeting asian and euro-tuners. on my 2001 gmc jimmy 4.3L w code, i installed the intake system 2 weeks after the flowmaster cat-back. no other mods were made at that time, and the exhaust increased my combined mpg from ft. lauderdal to miami airport commute by 1-1.5 mpgs on 87 octane using mobil gas. before the exhaust i was getting about 14-15 mpg's combined, as we have a lot of stop-go stop stop.....go traffic here in gods waiting room.
2 weeks after the cat back, i put the FIPK GEN II air filter on and it went up combined over 5-7 full tank to empty tank another 1-1.5 mpg's in the same commute. the only thing i feel is relevant to the intake system is the filter media is less restrictive than the box stock, and the tubes from the open filter box to the engine are more of a straight shot and larger sized and alow better air flow if the engine needs it. the air taken in is still from the same place as the stock box, just has more air available. the exhaust, in my opinion is a slight difference in back pressure, but mostly for the driver, as it just sounds better than stock.
i agree with the master that forcing more "cold" air in makes the computer send more gas, but the system i have is still an "as needed " type like stock, just that there is a higher limit on the air available if the engine asks for it.
I've done some other things i like but do not recommend to the average driver, as they don't help save milage, but have increased performance and i now average 16-18mpg's on the same commute as above, but i have jumped the perfomance for my own personal pleasure. with out the power upgrades, i was getting 17-19 combined. all turnpike milage last time i took the turnpike to orlando, i got 23 going up, and just a touch better coming home. with the upgrades i average i get a consistant 17-18 combined, but that gets shot down when i get into the performance part. becaus of all my upgrades, the improved milage is offset by the price of gas, as one of my upgrades requires 93 octane, so my out of pocket is back to where it was before and i spend the same amount of money as before, i just enjoy it more now.
I give props to the master, he has helped me many times. this is just my observation
thanks for everything.

[ZL1power69]

i installed an intake, catback exhaust, and an ignition wire upgrade and still get the same 13-15mpg in town. if i use acetone in the tank i'll get around 16-16.5

[excheezhead]

Originally Posted by ZL1power69

i installed an intake, catback exhaust, and an ignition wire upgrade and still get the same 13-15mpg in town. if i use acetone in the tank i'll get around 16-16.5

i put the same improvements on my 4.3L jimmy, and at first got the same results as you, untill i realized that it did not take as much right foot to get to the same speed as before. when i installed the right foot mod, things got better.
******WARNING********

using acetone is a fuel booster that has a demon side. if you are using acetone in any combination, pure, nail polish remover, etc., make sure you use a small mount of some king of lubricant, like a few drops of tranny fluid ot marvel mystery oil, red line, etc, as acetone is very good at removing things made of rubber, plastic, enamel, etc. ask your girl/wife, it can take off fingernail polish with a cotton swab, what do you think it's doing inside you fuel system, engine and exhaust?? i agree that it works, just don't use it in high concentrations. your vehicle will thank you.
i say these thing with much experience. during my navy tour, acetone was the catch all cleaning fluid of choice topside when we stripped, painted and removed everthing from paint to epoxy to stuff still unidentified by science.

[CanukGMC]

Originally Posted by old_master

Cold air intake systems are counterproductive. When the air is cold, the fuel mixture must be made richer because cold air is more dense than hot air. You HAVE to add more fuel for the engine to run correctly. That's the purpose of a choke and hot air intake system, (tube from exhaust manifold to air cleaner), on older vehicles. The fuel must be vaporized before it will burn efficiently, this is partially accomplished with heat in the intake manifold. Fuel mixes much more completely and easily with warm air. Basically a cold air intake system is nothing more than hype, added weight, and wasted money. Fact, not fiction!

another note on these "cold air kits". Think about it this way, how much can you REALLY drop the temp by relocating the intake? What? 5-10 deg at most? The tube will NOT make the air any cooler than the ambient temps outside the vehicle, when you are driving there's lot's of air coming in the front of the truck and from underneath, it's not like a sealed room, so the air under the hood, yes it's a few deg hotter, is still not THAT much warmer than outside.

PS: If cold air kits really added 10-20hp just by relocating the filter to draw in air that is 5-10deg cooler then using that theory when it's winter where I live (-50deg and lower) I should have like 200 more HP and about 67 mpg more right? Wrong.

[old_master]

Amen! Case closed!