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imhoffg 02-15-2013 10:20 AM

Improving Gas Mileage for a layman
Hey guys. New to the forum, but a long time fan of jeeps. I'm not a grease monkey nor do I have a garage or a large amount of car tools (i'm limited to a mechanics ratchet set mostly), but I know a enough to get by.

I'm looking for steps to take in order to improve my gas mileage in the 07 GC I just bought. Its a 3.7 v6 and I'm getting about 14. Granted, it is winter time, but I'm getting worse gas mileage than I did out of my '97 GC! With advances in tech and engine performance I would hope that I could at least match it....

I still love my GC and everything about it, just don't like shelling out unnecessary funds. Can anyone give me a list of things, in order, that a layman could do to improve fuel economy in a 3.7 v6? I already know tire pressure, but what about CAI and other things? Is there a good return on investment for these parts and are they hard to install if your not car guy but also not stupid? Would it be dumb to take it in to the dealership and have it checked out or are they just going to make a laundry list of unnecessary replacements for me?

any advice is appreciated

jerkylips 02-15-2013 11:03 AM

Best way to improve mileage in a 3.7 is to not drive it.. I have the same engine in my Liberty - mileage is terrible. I came from a 2000 Cherokee with the 4.0 inline 6, averaging around 20. With this one my average since I got it has been 16 (but more like 14 in the winter).

I did a seafoam treatment on mine. It made a big difference in the responsiveness, but pretty modest improvement in economy.

DannyVtCa 02-15-2013 11:21 AM

Re: Improving Gas Mileage for a layman
Get a chip or tuner, that's the only way to get better economy. Supporting mods would then be intake or drop in kn filter... And a muffler or full cat back. It's too bad they don't make headers for you guys.

Return on investment for modding for better fuel economy... Is years and years away. It's not a good investment. If you go with just a muffler (125), air intake(250) and chip(300) you would be maybe around 800 after muffler install. Your much better off switching to a good synthetic motor oil, synthetic gear oil, keeping on top of plugs, egr, map... Etc. All these things have to be done anyway.

Advice... Don't mod for fuel economy, mod because you like you jeep and want to make it special. Now that mine is all modded all I do it stomp on the gas all the time so my fuel economy is worse than before.

DannyVtCa 02-15-2013 11:24 AM

Re: Improving Gas Mileage for a layman
Man, those old 4 liter engines were awesome. I loved the Cherokees. They should bring them back.

imhoffg 02-15-2013 12:04 PM

Ok. What are your opinions on going to the dealership to have all those usual wear-out parts like O2 sensors and plugs checked out? Its got 88,000 miles on it so its gettin to that point, but im afraid of the dealership scam of being told i need to replace a laundry list of parts just cause theyre old (not actually broke). I did buy an extended warranty, but im not sure if that wouls cover inconvenient gas mileage....

Yeah i loved that old laredo. It was a L6 and very reliable. Sold me on jeeps forever, especially in snowy minnesota. Too bad she was getting to be worn out in the joints and not cost effective or reliable enough to trust driving to alabama in a couple months. RIP Pocahontas; may you find another worthy 16 yearold to cherish you for 7 years :)

DannyVtCa 02-15-2013 12:20 PM

Re: Improving Gas Mileage for a layman
Hey man, there is tons of great DIY on all maintenance for our jeeps on this site. O2 sensors get lazy after 70k and start to not work very well. If you crawl under your car you can pull an o2 sensor and check it out. It is looks cruddy, burned, white, black, etc it will probably need to be changed.

Pulling an o2 sensor for the first time after 88k will be a little hard. But on the plus side jeeps sit nice and high up so u dont need a jack. Getting it to start turning may be difficult, or it may just turn. Get yourself a good adjustable wrench, you may need a longer one and a short one to get to more difficult o2 sensors. Getting them unplugged from the wiring harness is kind of hard if you have big hands and arms... On my hemi it is a tight squeeze up above and pushing on the little release button and pulling it out can be a pain. I don't pay the dealerships a dime... I do everything from tranny flushes, suspension, and engine work. I figure the money I pay them I can get tools for much less and I will have those tools forever, whereas the money you give them is a one time thing. Jeep garage members are great and there when you need help and can't figure things out.

DannyVtCa 02-15-2013 12:28 PM

Re: Improving Gas Mileage for a layman
It is unlikely your o2 sensors have been changed. You might want to pull a few spark plugs and check their condition also. Air filter (15), plugs (20), o2 sensors (120), egr (40-50), pcv (20) and you just did a tune up for 200 dollars. The dealer would probably charge you 200 in labor depending on where you are. In vermont the labor rate was 75, here in california the labor rate is 120... I refused to pay either. A good local independent shop can do all those very, very easy also for less than a dealer. Shop around online, look for deals, you can get it much more reasonably and likely with free shipping.

Hemi egr's start to go at 50k. Our plugs need to be changed every 25k. I think of it in these terms. Is my time after work worth $100 an hour I'd pay a mechanic to do the job? Man, I wish I made $100 an hour

DannyVtCa 02-15-2013 12:34 PM

Re: Improving Gas Mileage for a layman
Check with the dealer to see if the warranty covers o2 sensors. All the other stuff I highly doubt. Also, o2 sensors are fragile, you don't want to pull one out and have it bounce around banging against stuff if your going to put it back in. A trick I use to protect them is wrap them in tin foil when they are pulled to protect them from dirt and being damaged.

imhoffg 02-15-2013 02:17 PM

Re: Improving Gas Mileage for a layman
I see on autozone that there are two brands, bosch and denso. The bosch is half the price, but some DIY sites suggested them. Is there a price to quality ratio. Both the upstream and downstreams are the same price between the brands so it's not the part itself, just the brand difference that is affecting the cost as far as i know?

DannyVtCa 02-15-2013 02:24 PM

Re: Improving Gas Mileage for a layman
Stay with ntk or ngk o2 sensors. They are the original kind. The Bosch and other brands can throw codes because they don't heat up in the require amount of time.

imhoffg 02-15-2013 02:47 PM

Re: Improving Gas Mileage for a layman
and will a worn out o2 sensor be very obvious or will it take a trained eye? I just don't want to drop $200 on replacements for parts that are still good. I google imaged "bad oxidation sensor" and got some idea of what it looks like.

Thanks for all your help by the way, danny

ChrisWk 02-15-2013 03:22 PM

Re: Improving Gas Mileage for a layman
Well I say if you are going to keep the jeep for the next 3years or more do all the stuff the guys told you to do, if you are not put gas and change oil in and sell it. Look around for a good garage if you can not do the stuff yourself but the fun part is fixing it yourself and feeling good you did yourself.

Good luck.

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