Improved my gas mileage

[BlueJeep07]

On my 3.7L v6 I took off the little plastic piece that sits in front of the air intake. It looks like it is there to protect against water being thrown over the hood, but it is useless on a jeep like mine that is 100% on road. Before I removed it I averaged about 21 mpg. Now I get about 23 mpg. About a 10% increase just by removing a little piece of junk. I had bought a cheap cold air intake, but this worked out so well that I never bothered with the CAI.

Also, for those wanting good mileage, I have found that the two best things that I can do to keep good MPG's is to keep my tires fully inflated and get into overdrive (6th gear) as soon as possible. I use synthetic oil, but I've never noticed a mpg difference over conventional.

 

[VTNomad]

Mpg

Smooth constant acceleration is the best thing to do to increase mpg's. Slamming on the gas to get up to speed as quickly as possible is a bad idea.

 

[JeepJeepster]

What year is your Jeep? That baffle probably keeps rain out of the intake at hw speeds also. Just be careful if you ever get in very heavy downpours. The CRD's are known to fill up with water since there intake points right out of the grill so it can happen.

All libertys except for CRD's have 4 gears.

 

[J-Thompson]

I would use EXTREME caution when removing any shield on the air box
like Jeepster said it probably keeps water out
also you said that you keep your tires fully inflated
this is not going to save you money but in the end cost you
it will cost you tires
over inflated wear in the center before the edges
oh and on top of that over inflated tires also get poor traction not just off road but on road as well so when the center is worn all the money you saved on fuel will be out the window when you slide off the road due to poor traction and if your lucky only destroy you KJ not your life as well

Common sense goes a long way and to me this fall very short

 

[JeepJeepster]

well, it would amaze you how many people never check their tire pressure. I would say bluejeep meant he just makes sure they are at their proper psi(I could be wrong though).

Although it amazes me that people post its best to keep their tires right at 44psi since their sidewall says thats the max psi.

I wouldnt go over 36psi.

 

[ms5490renegade]

my evic says the right front tire has 40psi
i checked with the hand held pressure monitor and it says 30. which one is wrong?

 

[MoladoGuy]

my evic says the right front tire has 40psi
i checked with the hand held pressure monitor and it says 30. which one is wrong?

Go find another hand held pressure monitor or stop through a local shop to check it out. 30 psi should be noticeable by looking at the tire and comparing it to the rest. But to be safe just get a 3rd tool involved to test it out.

 

[BlueJeep07]

I hear what you're saying about possible rain getting into the intake, but I've had other vehicles (focus, lancer) with identical looking intakes that came that way from the factory. I think for rain to get in the intake it would have to be pretty much a hurricane blowing horizontal rain.

J-Thompson you read my message wrong. I said that I keep my tires fully inflated, not overinflated. I think the Jeep calls for 35 pounds per tire.

 

[jeepkj02]

my evic says the right front tire has 40psi
i checked with the hand held pressure monitor and it says 30. which one is wrong?

Go to autozone and pickup one of those 99-cent pen style tire gauges. I like to set mine at 35psi cold.

 

[Treyz02KJ]

Smooth constant acceleration is the best thing to do to increase mpg's. Slamming on the gas to get up to speed as quickly as possible is a bad idea.

but it sure is fun...

 

[Rush345]

Check out this link on LOST by MonsieurGlen
http://www.lostkjs.com/forum/phpBB2/viewtopic.php?t=11748&postdays=0&postorder=asc&start=15
Since doing the same to my 2002 Sport I have noticed better milage and performance.

 

[ms5490renegade]

i checked with another one and it said 30psi. how do i change the evic to the correct psi ?

 

[Ry' N Jen]

Good day,

The small plastic "flap" at the opening of the air intake trumpet that you are referring too, I believe is there to reduce air induction noise. Predominantly whilst driving at speed. (I could be wrong and I'm sure someone will gladly chime in and correct me.)

ry'

 

[moparman]

Everything that J-Thompson says about tire wear is true but less so with radials over a bias ply tire. You can make pretty big air pressure changes without affecting the contact patch on a radial tire. It does change the spring rate of the tire, that is why racers fine tune their car with tire pressure settings. The wrong width rim is a bigger factor. I would bet that 28 to 40 psi or so may not change much except for the ride. Underinflating is a bigger problem for bad weather. (More on this at Tire Rack's website.) Overinflation would help you slide off the road in bad conditions but my experience it takes over 48 PSI or so for that to happen. Offroading would probably suck too. Usually the manufacturer's PSI setting is primarily for ride quality (if it is in the 20's) or MPG. (if it is in the mid 30's) I have been running 3-5 PSI higher than stock on many sets of tires on about 10 vehicles for the last 25 years. (about 30k miles a year) I have also run 45-50 PSI in other vehicles at the drag strip or autocross. I run about 36 PSI in my Jeep, at 31K miles, no problems at all. My Jeep calls for 33 PSI. The 44 PSI on the sidewall is for maximum load rating. Take that load rating and multiply it by 4, probably a good bit higher than the GVW of the vehicle. So I would consider that setting if I was fully loaded up with fuel, passengers and cargo.

also you said that you keep your tires fully inflated
this is not going to save you money but in the end cost you
it will cost you tires
over inflated wear in the center before the edges
oh and on top of that over inflated tires also get poor traction not just off road but on road as well so when the center is worn all the money you saved on fuel will be out the window when you slide off the road due to poor traction and if your lucky only destroy you KJ not your life as well

Common sense goes a long way and to me this fall very short

 

[Atrus]

I wouldn't hesitate to remove that baffle. I gutted the heck out of the one on my Grand Prix and had it open behind the headlight and into the fenderwell. 70k miles that way with 0 issues.

 

[Ry' N Jen]

Check out this link on LOST by MonsieurGlen
http://www.lostkjs.com/forum/phpBB2/viewtopic.php?t=11748&postdays=0&postorder=asc&start=15
Since doing the same to my 2002 Sport I have noticed better milage and performance.

Interesting topic.
I'm actually thinking of using a Suzuki Sprint Turbo hood scoop* like the two that I have on my green Mini. They are functional and the opening for the inlet is equal in size to that of the one attached to the Liberty's air box.
It's either either a Suzuki hood scoop or one off of a 1984-89 Nissan 300ZX** which I happen to have a couple of lying around collecting dust.
Anyway both have a rubber seal which attaches to the scoop and seals against the air box. Both of them would supply the engine with plenty of direct cold air flow.
As far as water is concerned, I see quite a few still photo's as well as "You tube" video's showing Liberty's fjording water, where the water comes up over the hood submerging the whole front clip. These KJ's don't have any snorkels fitted either. What keeps them from sucking in water and hydro locking?
And as far as cutting a hole in the hood?
If it gives good results it will be worth it. If not, I guess I buy a new hood.
Or, sell all the hood scoops I'm not using and earn more than enough to buy a snorkel.
I'd like to hear your views on this.





http://vegetable09.piczo.com/mypics?cr=6&linkvar=000044*
http://www.garymolitor.com/300zx/scoop/nissan_300zx_replica_200zr_hood_.htm **
http://pictures.topspeed.com/cars/n...-series-ar36885/IMG/jpg/e/nissan_300zx_6w.jpg**

Oh yeah, if you check out Jen's wbsite, {*} just scroll down past the crap.

 

[LibertyFever]

well, it would amaze you how many people never check their tire pressure. I would say bluejeep meant he just makes sure they are at their proper psi(I could be wrong though).

Although it amazes me that people post its best to keep their tires right at 44psi since their sidewall says thats the max psi.

I wouldn't go over 36psi.

I agree, I seldom think about my tire pressures when I'm off the trail. Which either leads to sloppy handling or super hard bumps.

For my Liberty Sport and my stock tires I find that about 22lbs of air does well. Even tire wear & fair gas mileage.

The best and cheapest way to improve your gas mileage is changing your driving habits. Accelerate slowly & coast to stops. Those gadgets they sell on TV ads simply don't work.

When I was shopping for an SUV I thought because of its size a Liberty would get better mileage than a Cherokee but actually the weigh about the same.
The best mileage I can hope to get is 22MPG which isn't much better than my 4cyl YJ running on 33's (16MPG).

 

[Boblemoche]

Can someone explain to me how a CAI or removing the plastic part on the grill can improve MPG. I understand that better flow and denser air will increase max power but MPG ? If your cruising at 70 and you have more air coming from the intake the trottle body will close slightly more to keep the same amount of air going in the engine and keep the same power or else you will run you engine too lean or the ecu will send more gas to the engine and you will go faster

 

[tjkj2002]

Can someone explain to me how a CAI or removing the plastic part on the grill can improve MPG. I understand that better flow and denser air will increase max power but MPG ? If your cruising at 70 and you have more air coming from the intake the trottle body will close slightly more to keep the same amount of air going in the engine and keep the same power or else you will run you engine too lean or the ecu will send more gas to the engine and you will go faster

You answered your own question.

Oh and by the way the throttle plate will not close a little by itself,in the '02-'06 KJ's it is a direct link to the gas pedal and opens/closes via your foot,'07 KJ's and '08 KK's use a electric motor and that can be effected but not for the older KJ's.

 

[Boblemoche]

I understand more air = more power but more power does not mean more fuel economy

Lets say your cruising at 70 then suddenly with some magic you get a CAI then more air and more power so you accelerate but you want to stay at 70 so you release your foot a little and close slightly more the TB to get back to 70 you just moved the flow restriction form the intake to the TB. Where is the fuel economy ?