The Official "My Gas Mileage *****" Thread

[sota]

I've been bucking 20mpg finally for a couple tanks with mixed driving and using some "hypermiling" tricks.

 

[sota]

oh and tjkj is right.

 

[redpoint5]

Boy you need to stop thinking everything you read on the internet is true or lay off the wacky weed.

:smokin:

I have never used an illicit drug, and I question everything people tell me. That's why I am correct more often than not.

You will get worse mpg's at higher altitude,known fact and has been known for over 70 years.

70 years ago engines used carburetors. Carbs do not have the ability to adjust to changes in air density and essentially run in "open-loop" mode. As elevation rises, density decreases and the air/fuel ratio goes rich. As you know, a rich mixture means fuel is entering the engine but not being burned. In a modern fuel injected vehicle, the A/F ratio is maintained regardless of air density by use of sensors and a computer. This is why cars used to get worse fuel economy at elevation.

You loose HP and higher altitude,again another known fact for over 70 years,which means your engine must work harder at higher altitude thus worse mpg's.For how much power you loose at high altitude is far greater then the advantage of driving through thinner air.

An engine looses peak horsepower, but how often is an engine operated at peak power? A given HP still requires the same amount of fuel to be burned regardless of elevation. The throttle must be pushed further at elevation because there is less air available, not because it is delivering more fuel to achieve the same power output. Example: At sea-level a 25% throttle opening is required to produce 30hp. At 8,000ft, a 35% opening is required to deliver the same amount of air to produce 30hp. The amount of fuel burned does not change, only the throttle opening.

Where your throttle is has everything to do with how much gas you use as the TPS sends info to the PCM to match fuel flow for throttle position.The KJ already comes with a CAI right from the factory.

Not entirely accurate. The throttle has everything to do with restricting air to the engine. Opening the throttle allows more air to enter the engine and the PCM calculates how much fuel to deliver based on airflow and O2 sensor readings (along with TPS). Since air is less dense at elevation, larger throttle openings are required. The PCM will only deliver an amount of fuel required to maintain a stoichiometric air-to-fuel ratio; about 14:1.

The only reason more fuel would be delivered to the engine than can be fully burned is an open-loop condition, which often happens at full-throttle. Unless the driver is in open-loop, no excess fuel is wasted.

At 8,000ft of elevation, the air is only 75% as dense as at sea-level. This directly equates to 25% less wind resistance, which is by far the biggest contributor to fuel consumption at highway speeds. This is the reason that airliners gain altitude as fast as possible. The thin air presents less resistance to the aircraft, which is well worth the corresponding loss in power (and fuel consumption).

Your whole post and everything in it would leave,like myself,any ASE Master Tech rolling on the ground laughing and give most automotive engineers a heart attach.

The logical fallacy committed here is known as "appeal to authority". Even if 99% of people thought I was a raving lunatic, it doesn't change physics and the facts that I have accurately presented. Most "experts" used to believe the earth was flat too. Engineers on the other hand, have no excuse for being wrong.

 

[tjkj2002]

:smokin:

I have never used an illicit drug, and I question everything people tell me. That's why I am correct more often than not.



70 years ago engines used carburetors. Carbs do not have the ability to adjust to changes in air density and essentially run in "open-loop" mode. As elevation rises, density decreases and the air/fuel ratio goes rich. As you know, a rich mixture means fuel is entering the engine but not being burned. In a modern fuel injected vehicle, the A/F ratio is maintained regardless of air density by use of sensors and a computer. This is why cars used to get worse fuel economy at elevation.





An engine looses peak horsepower, but how often is an engine operated at peak power? A given HP still requires the same amount of fuel to be burned regardless of elevation. The throttle must be pushed further at elevation because there is less air available, not because it is delivering more fuel to achieve the same power output. Example: At sea-level a 25% throttle opening is required to produce 30hp. At 8,000ft, a 35% opening is required to deliver the same amount of air to produce 30hp. The amount of fuel burned does not change, only the throttle opening.



Not entirely accurate. The throttle has everything to do with restricting air to the engine. Opening the throttle allows more air to enter the engine and the PCM calculates how much fuel to deliver based on airflow and O2 sensor readings (along with TPS). Since air is less dense at elevation, larger throttle openings are required. The PCM will only deliver an amount of fuel required to maintain a stoichiometric air-to-fuel ratio; about 14:1.

The only reason more fuel would be delivered to the engine than can be fully burned is an open-loop condition, which often happens at full-throttle. Unless the driver is in open-loop, no excess fuel is wasted.

At 8,000ft of elevation, the air is only 75% as dense as at sea-level. This directly equates to 25% less wind resistance, which is by far the biggest contributor to fuel consumption at highway speeds. This is the reason that airliners gain altitude as fast as possible. The thin air presents less resistance to the aircraft, which is well worth the corresponding loss in power (and fuel consumption).



The logical fallacy committed here is known as "appeal to authority". Even if 99% of people thought I was a raving lunatic, it doesn't change physics and the facts that I have accurately presented. Most "experts" used to believe the earth was flat too. Engineers on the other hand, have no excuse for being wrong.

You still have zero knowledge of how Fuel injection works at sea level or 8000'.Let alone actual knowledge of actual effects of altitude.Come spend a week driving where I live and I'll bet you $1000 you will get far worse mpg's then what your getting now at your lower altitude.

I can also tell you that the "magic" 14.7:1 air/fuel ratio(which you couldn't even get right) is really a thing of the past in most cases.

 

[rockymountain]

...and there is no airflow sensor in our KJs.

just manifold pressure, which I don't know where that would be calculated in.

 

[tjkj2002]

...and there is no airflow sensor in our KJs.

just manifold pressure, which I don't know where that would be calculated in.

Does pretty much the same thing as a MAF sensor does just in a different way.Basically calculates elevation.

 

[Dave]

^^all this mumbo-jumbo mechanicalistic stuff......:smokin:...bottom line is the KJ is an obese aerodymamicly challenged porker and every mod we do like lift/bigger heavier tires and such just adds to its portlyness....:smokin:

My pig needs gas again...........:smokin:

Dave

 

[ThunderbirdJunkie]

^^all this mumbo-jumbo mechanicalistic stuff......:smokin:...bottom line is the KJ is an obese aerodymamicly challenged porker and every mod we do like lift/bigger heavier tires and such just adds to its portlyness....:smokin:

My pig needs gas again...........:smokin:

Dave

Dunno what your problem is, ThunderbirdJunkie's Jeep hasn't needed gas in months :beer:

 

[tjkj2002]

Dunno what your problem is, ThunderbirdJunkie's Jeep hasn't needed gas in months :beer:

Gotta drive it,sitting in the driveway doesn't count:happy175:

 

[Dave]

^^guess I will have to chain mine up to the hitching post at night. Must be using gas at night when I am not looking.....:smokin:

Dave

 

[iamweasel]

Gotta drive it,sitting in the driveway doesn't count:happy175:

I need to drive mine LESS Sitting in peak-hour traffic twice a day is giving me sub 12 mpg :disgust:
nah, I love my Jeep :smokin: no previous daily driver has put a smile on my face like the Jeep has

 

[capeKJ]

I've been averaging about 13-15 city and right around 18-19 highway according to the display, sometimes I wonder how accurate it is because according to my own calculations I've been getting slightly less than what the display reads. For an 11 year old jeep I cant really complain.. Only time I get really annoyed is sitting in dead traffic commuting into the city...I feel like I can almost see the gas gauge slowly moving towards empty

 

[DaleKJ]

I-20 from Dallas to Midland, cruise at 65, AC on low got 24.2 mpg. Coming back set cruise at 75, got 20.3. Around town 17-18 is usual.
2004 KJ with 26,000 miles. True story. Picked it up in showroom condition with 23K about 3 months ago. Was used as a tow behind for a Motorhome.

 

[a_ibrahem]

Fuel system cleaner

hello guys ,

have a question about fuel system cleaner sold in the market ,
are they really helping ?

my jeep is 2007 and it has 130,000 km on it already

i feel like the injectors needs cleaning ,it doesnt sprint like it was new at all

also can i add one bottle of these to half a tank only ,just to make it more concentrate and clean better ?

appreciate your feedback guys,

BR,
Ahmed

 

[dude1116]

hello guys ,

have a question about fuel system cleaner sold in the market ,
are they really helping ?

my jeep is 2007 and it has 130,000 km on it already

i feel like the injectors needs cleaning ,it doesnt sprint like it was new at all

also can i add one bottle of these to half a tank only ,just to make it more concentrate and clean better ?

appreciate your feedback guys,

BR,
Ahmed

I used a couple of these in the winter and saw no difference. A lot of people like to add seafoam to a tank of gas. Not sure if that has helped people. I'm sure others can chime in.

 

[CzarKJ]

Helped me out some but mine wasn't taken care of as well as it should have been. I'm going to seafoam the vaccum line and some in the oil during my next change.

 

[mongo]

First tank full in my 02 20.5mpg 70% highway

 

[Luke]

FWIW .. the dealer service made a much bigger difference than any additives that I put in to clean the injectors. It's not free by any means but it works.

 

[a_ibrahem]

FWIW .. the dealer service made a much bigger difference than any additives that I put in to clean the injectors. It's not free by any means but it works.

Thanks man ,you just confirmed what i was wondering for a while
am going in the morning to the dealer for service ,will let them clean the injectors also.

BR,
Ahmed

 

[tommudd]

Guess I left off the gas to take the picture but it shows what I got after almost 500 miles of driving according to the Scan Gauge
I also hand calculated it and was almost the same
I do see where I was doing 74 in a 65 according to the GPS, whoops

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