Improving gas mileage

[rjkj2005]

Hey! Good advice. Thanks!

I got worn tires (that'll be replaced soon), that might also contribute to the bad mileage I'm getting. Assuming rear/front diff lubes were never replaced since 2003 - that should be relatively easy.

I am new to many of these terms.
Can you explain about : IAC/ports, PCV, filler tube? not sure what/where they are.

Worn tires would give you better fuel milage. Less rolling resistance.
IAC = idle air control
It's mounted to the throttle body. It gets carbon build up and doesn't alow the motor to idle at the proper rpm. Or causes a rough idle.

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[rjkj2005]

Hey! Good advice. Thanks!

I got worn tires (that'll be replaced soon), that might also contribute to the bad mileage I'm getting. Assuming rear/front diff lubes were never replaced since 2003 - that should be relatively easy.

I am new to many of these terms.
Can you explain about : IAC/ports, PCV, filler tube? not sure what/where they are.

The pcv valve is located on the oil fill tube. It pulls blow by out of the motor and puts it back into the intake to be burned again.

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[LibertyTC]

I am new to many of these terms.
Can you explain about : IAC/ports, PCV, filler tube? not sure what/where they are.

The IAC, intake air control and the port it sits in, can be cleaned & removed easily.
Geez time fly's, it was 8 years ago I posted this.. see post 10 LINK: http://www.jeepkj.com/forum/f196/idle-air-control-no-screws-44826/
The throttle body is easy to clean, open the butterfly/throttle plate, by hand with it running in park, and spray some throttle body cleaner down inside the bore@ 1800 rpm. I
I also like to clean the outside edge of the throttle plate, and then apply a bit of machine oil, as mine can get a bit sticky if it carboned up.
The PCV turns counter clockwise to remove it.
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Pull the baffle out of the oil filler neck, if you have one and have a peak inside, it should be clean...
See post 4 link: http://www.jeepkj.com/forum/f196/possible-head-gasket-leak-please-help-58803/
Hope this helps.

 

[tommudd]

Worn tires would give you better fuel milage. Less rolling resistance.
IAC = idle air control
It's mounted to the throttle body. It gets carbon build up and doesn't alow the motor to idle at the proper rpm. Or causes a rough idle.

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First time I ever heard that in my life and I spent a lot of time behind the counters of tire shops :icon_razz:

 

[tjkj2002]

Worn tires would give you better fuel milage. Less rolling resistance.
IAC = idle air control
It's mounted to the throttle body. It gets carbon build up and doesn't alow the motor to idle at the proper rpm. Or causes a rough idle.

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Got it backwards,worn tires have more traction(on dry pavement) thus decreasing mpg's.

Just like anyone stating a clean air filter gives you better mpg's,totally false unless your running a pre-'96 vehicle(non-OBDII) or a carbed engine.A dirty air filter will actually increase mpg's on a OBDII controlled vehicle.

 

[rjkj2005]

First time I ever heard that in my life and I spent a lot of time behind the counters of tire shops :icon_razz:

Worn tires have less rolling resistance do to less tread. I've put over 2,000,000 mile out there over the road in 15 years in 4 different trucks and watched fuel milage like a hawk. And as the tires wore the milage increased. And everytime a set of new tires were put on the milage would go down. By as much as 1.5 mpg. I always hated new tires for that reason. The last 2 trucks I owned had tire wear built into the computer. it would adjust the speedometer and odometer for wear of the tires. It would have to be reset when new tires were put on. You had to put in revs per mile and tread depth of the new tires. And an estimate of how many miles till tire would be worn down to a certain tread depth. Then as the miles are put on it would keep everything calibrated.

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[rjkj2005]

Got it backwards,worn tires have more traction(on dry pavement) thus decreasing mpg's.

Just like anyone stating a clean air filter gives you better mpg's,totally false unless your running a pre-'96 vehicle(non-OBDII) or a carbed engine.A dirty air filter will actually increase mpg's on a OBDII controlled vehicle.

Lol. Yea. Well let me ask you something. Is it easier to spin the tires on dry pavement on new tires or worn out tires.
If your thinking that's why drags use slik tires for more traction. Yea your right. But the rubber compound is much softer than a street tire. And wouldn't last 1000 mile drive everyday on the street.

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[tjkj2002]

Lol. Yea. Well let me ask you something. Is it easier to spin the tires on dry pavement on new tires or worn out tires.
If your thinking that's why drags use slik tires for more traction. Yea your right. But the rubber compound is much softer than a street tire. And wouldn't last 1000 mile drive everyday on the street.

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Less tread always equals more traction on dry pavement.Wet pavement/snow/ice/mud/sand/gravel is were more tread equals more traction

 

[rjkj2005]

Less tread always equals more traction on dry pavement.Wet pavement/snow/ice/mud/sand/gravel is were more tread equals more traction

Keep telling yourself that.[emoji1]

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[tjkj2002]

Keep telling yourself that.[emoji1]

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It's called physics,so yeah I will since it's the truth.

 

[CzarKJ]

opcorn:

 

[rjkj2005]

So your telling me. If we had the same tires. That if you ground off all the tread on your tires and I had full tread on mine in equal vehicles you would win the drag race or even a road course race on dry pavement.

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[Adam Roby]

I wonder, when a tire is new, the tread is tall and therefore much softer at the ends where it meets the road. That must aid in giving the tire some "bite" on the street surface. As that tread wears down, it gets harder and harder because it flexes less, so once the tire is bald there is no more flex and could possibly give it less traction.

That is just an observation, or an idea based on some possible logic... whether proven or not I don't know. Sounds pretty good to me, especially since I just made it all up.

 

[KJ604]

think about indy/F1 cars. the dry tires have no tread. the rain tires have grooves.

more aggressive street tires have less tread on them then an all season tire.

the best tire, in terms of traction, on a DRY road, has no tread on it.

tread aids in giving the water a channel to go into instead of being sandwiched between the rubber and the asphalt.

its a matter of surface area in contact with the asphalt. a tire with no tread has more square inches in contact with the road than a tire with tread on it. more surface area in contact with the road = more traction

 

[tommudd]

Just sitting back laughing at some of this
Oh well :Insane:

 

[profdlp]

Less tread always equals more traction on dry pavement.Wet pavement/snow/ice/mud/sand/gravel is were more tread equals more traction

Keep telling yourself that...

tkjk2002 is right. That's why drag racers have essentially bald tires. If they didn't have the extra traction they'd just sit there at the gate spinning their wheels.

 

[rjkj2005]

tkjk2002 is right. That's why drag racers have essentially bald tires. If they didn't have the extra traction they'd just sit there at the gate spinning their wheels.

Yall at talking about 2 different types of rubber. drag slicks are a Much softer compound., and yes they grip like crazy.
Now let's look at the 50,000 mile tire. Much harder rubber it gets its grip from the lugs. if you had a set of brand new BF K0's and they forgot to put the tred pattern on so they were smooth and you went to the drag stip. You would be left spinning your wheels at the starting line. Verse a set of drag slick
Sure if racing I'd want as much tire on the road as possible for gip. Given it was the right rubber for the job. You can't compare apples to oranges when it comes to rubber.
Oh and by the way is not about physics it's about chemistry

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[ozone000]

Racing slicks are not the same as worn tires, though, and rjkj2005 didn't say racing slicks gave better gas mileage, just that (semi) truck tires, when worn, give better gas mileage.

I cannot attest to the truth as I know little about commercial truck tires. I'm just pointing out that you are all talking about different things.

Though from Tire Tech Information - Tire Rolling Resistance Part 3: Changes to Expect When Switching from Worn-Out to New Tires

New, Full-Treaded Tires Generate More Rolling Resistance Than Shallow-Treaded, Worn Tires
Tire rolling resistance gradually drops by about 20% during the life of a tire as the tread wears from its original molded depth to worn out. This can be attributed to the reduction in tread mass and rubber squirm, as well as subtle hardening of the tread compound during years of service and exposure to the elements.

While this gradual reduction in tire rolling resistance and minor increase in fuel economy may be too subtle to register during the tire's life on a tank-by-tank basis, the virtually instantaneous switch from worn tires to new tires (even if they are the same brand, type and size) will typically result in an increase in rolling resistance of about 20%. Since the automotive industry estimates a 10% increase in tire rolling resistance will result in a 1% to 2% decrease in vehicle fuel economy, drivers should expect to experience a potential 2% to 4% decrease in mpg.

 

[KJ604]

Oh and by the way is not about physics it's about chemistry

I think kinda both.

But you are also correct about the compound being the difference there. Road compounds cant be compared to race its completely different and yea, a racing slick made out of road compound would be garbage.

 

[CzarKJ]

Yall at talking about 2 different types of rubber. drag slicks are a Much softer compound., and yes they grip like crazy.
Now let's look at the 50,000 mile tire. Much harder rubber it gets its grip from the lugs. if you had a set of brand new BF K0's and they forgot to put the tred pattern on so they were smooth and you went to the drag stip. You would be left spinning your wheels at the starting line. Verse a set of drag slick
Sure if racing I'd want as much tire on the road as possible for gip. Given it was the right rubber for the job. You can't compare apples to oranges when it comes to rubber.
Oh and by the way is not about physics it's about chemistry

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Ya I have to interject after that statement. Those two do not work separately people. Chemistry uses physics as much as physics uses chemistry. Friction coefficients would not exist without molecular compounds that allow or disallow them. In basic chemistry you are actually being taught physics.