From decent to bad: Gas mileage

Thanks for the tips. I am not real concerned about capacity since I have been using 16.5 all along. The mileage will stuck suck.

I am going to check the rear brakes for drag.
 
I haven't had a chance to check out the truck due to work and freezing temps but the mileage continues to decline. 13.5 was the most recent mileage.

However, I slow-filled it and got 17.2 gallons in. Filling it slowly DOES seem to make a difference on how much fuel you can get in.

233 miles on 17.2 gallons. :(

Now I'm starting to regret selling my TJ. It was a 99 2.5L and got 18.5 MPG.
 
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I haven't had a chance to check out the truck due to work and freezing temps but the mileage continues to decline. 13.5 was the most recent mileage.

However, I slow-filled it and got 17.2 gallons in. Filling it slowly DOES seem to make a difference on how much fuel you can get in.

233 miles on 17.2 gallons. :(

Now I'm starting to regret selling my TJ. It was a 99 2.5L and got 18.5 MPG.
That's not a fair comparison. If you used a different fill technique, you need to ignore that mileage reading (you basically got an extra 2-3 gallons in the tank that you didn't get in there on the last fill-up). The next fill-up MPG will be valid if you use the same fill technique.

-Charlie
 
That's not a fair comparison. If you used a different fill technique, you need to ignore that mileage reading (you basically got an extra 2-3 gallons in the tank that you didn't get in there on the last fill-up). The next fill-up MPG will be valid if you use the same fill technique.

-Charlie

So I was heading to the gas station today and ended up running out of gas at 236 miles. Luckily I had a gallon and half in my gas can and was able to get to the gas station. So my 13 mpg continues. What's even more odd is that I could only get 15.8 gallons in the tank. It would not take anymore even while slow filling.


I dunno what is going on but I am getting frustrated. :mmph:
 
Don't get too depressed yet.

I just did a 3500 mile road trip from NE Ohio to Colorado and back and on my continues drives with cruise set at 70 MPH, even without a ton of wind, I was only getting 18-19 MPG. Cold weather affects fuel mileage very negatively for a couple reasons.

1. Winter fuel blends are known to be blended with about 2-3% less energy per volume than summer blends.

2. Cold air is much more dense. Air density at 20 degrees F is about 10% greater than at 70 degrees F. On my way back from CO I never saw temps get above 13 degrees F and at times were as low as -7. No wonder I was only getting 17 on those fillups.

3. Low temperatures means higher viscosity for fluids, oil, trans fluid, etc, and therefore a longer time to warmup which creates more drag and thus less efficiency.

I don't think 13-14 MPG banging around is all that crazy considering the extremely cold temps we have been experiencing.
 
Don't get too depressed yet.

I just did a 3500 mile road trip from NE Ohio to Colorado and back and on my continues drives with cruise set at 70 MPH, even without a ton of wind, I was only getting 18-19 MPG. Cold weather affects fuel mileage very negatively for a couple reasons.

1. Winter fuel blends are known to be blended with about 2-3% less energy per volume than summer blends.

2. Cold air is much more dense. Air density at 20 degrees F is about 10% greater than at 70 degrees F. On my way back from CO I never saw temps get above 13 degrees F and at times were as low as -7. No wonder I was only getting 17 on those fillups.

3. Low temperatures means higher viscosity for fluids, oil, trans fluid, etc, and therefore a longer time to warmup which creates more drag and thus less efficiency.

I don't think 13-14 MPG banging around is all that crazy considering the extremely cold temps we have been experiencing.

I understand all that can factor into mileage, however, I have been driving Jeeps and other vehicles over the years through many winters and never experienced such a huge drop.

I bought this truck last year in December and drove it through the winter. I did run out once at 302 miles in January and that's when I realized the gauge was not reading right.

I'm heading over to my mother's 2nite cuz she has a heated garage and I am going to dig into this rig and see what I can find. I plan to take off the throttle body and clean it up along with the sensors since it's due for a cleaning. I really think that the rough idle I experienced recently has something to do with it and the shop sprayed MAF cleaner in the TB to clear it up.

i will update with what I find.
 
I understand all that can factor into mileage, however, I have been driving Jeeps and other vehicles over the years through many winters and never experienced such a huge drop.

I bought this truck last year in December and drove it through the winter. I did run out once at 302 miles in January and that's when I realized the gauge was not reading right.

I'm heading over to my mother's 2nite cuz she has a heated garage and I am going to dig into this rig and see what I can find. I plan to take off the throttle body and clean it up along with the sensors since it's due for a cleaning. I really think that the rough idle I experienced recently has something to do with it and the shop sprayed MAF cleaner in the TB to clear it up.

i will update with what I find.

First off, stop running out of fuel. When the gauge reads low, and the light comes on, fill up regardless of miles.

I would try cleaning the MAF sensor.

Info in THIS THREAD.
 
First off, stop running out of fuel. When the gauge reads low, and the light comes on, fill up regardless of miles.

I would try cleaning the MAF sensor.

Info in THIS THREAD.

The gauge was between 1/4 and half and light was not on but it ran out. Gauge was pretty accurate the past couple months and finally this time it was not and I had no idea how much gas I had left.

Thanks for the link. I will do that. I tried to get to it today but I was busy trying to put my jeep back together and by the time I got it out of the carpart the weather took a dive and it got really cold.

We are getting hit by some severe cold weather. It is supposed to go down to -9 and that is rare here.
 
So the MAF sensor was clean but i cleaned it anyways. i noticed fluid in intake tube and decided to investigate further. Not sure what this tube is but it is under the throttle body and makes a squarish 180 turn to the back of the engine. It was full of fluid. I assume condensation or water but can't be good. What is this tube and do I have to drain it out from back of the engine? I drained what I could and now cleaning the throttle body and bottom sensor.

Edit: I forgot that these engines have cooled throttle bodies so never mind on that.

However, the in take box that attaches to the throttle body had fluid of some sort in it and I had to shake it out a bit.
 

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Well this aint good....


edit: turn out it is coolant.
 

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Yeah, that coolant is supposed to be there...

Though, your cooling system looks like it has had a tough life! Make sure you get new gaskets for the IAC valve when you reinstall it, and clean up those sealing surfaces.

-Charlie
 
Iac

Did you test out the little motor in the IAC to make sure the cam is moving properly/freely? Would be nice to test it before and after cleaning to see how much it helped. That coolant junk in there looks pretty bad. Was it clogging the IAC path significantly, or just more cosmetic?
 
Did you test out the little motor in the IAC to make sure the cam is moving properly/freely? Would be nice to test it before and after cleaning to see how much it helped. That coolant junk in there looks pretty bad. Was it clogging the IAC path significantly, or just more cosmetic?

I am not familiar with how to test that motor. I just took everything apart, cleaned the best I could, and reinstalled. I did not have a new rubber gasket for the TB so I cleaned the old one, lubed it a little, and reinstalled. It was still in good shape.

I didn't notice anything different on the drive home.

According to the maintenance records, the PO had a radiator implosion...TWICE....so the transmission fluid and coolant mixed If I'm not mistaken and I think that may have caused that buildup in the cooling system. I flushed the radiator a few months ago for winter preventive maintenance.

I'm just wondering how that liquid got into the air intake box, the one that attached to the throttle body. There is a crevice where water poured out of as I turned it over. The air filter box was dry.
 
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