Troublesome kk...

PALiftedKK · **Posted:** Tue Dec 15, 2015 7:53 pm

So yall know how well i keep her maintained and mall crawler clean when i dont wheel. But im having serious issues with mileage recently... Started having this issue well before Morgans 120lb bumper.

So heres what ive checked so far, egr was cleaned recently, air filter washed and oiled 1k miles ago and still clean, spark plugs replaced 4k miles ago (i have 33k miles), oil changed every 2500-3500 miles. Brakes dont drag. Transmission and diff fluids are fine. Oxygen sensors are reading normal up and downstream.

Ive driven like a grandma the last 3 tanks. Every other tank ive been throttle heavy. Mileage is near the exact same between the two on paper. 200 miles os what i get a tank.

Any one have a clue whats going on? No codes either. I dont like an early or suprise Christmas.

LittleRed · **Joined:** Sun Nov 29, 2015 8:25 pm **Posts:** 4

i have a 2012 liberty with a 2 in lift, 265/60/18 and a 10,000 lb winch on the front. and my millage is in the dumper. i get about 15MPG, new i was only getting 17 max. i just chalked it up to the added weight. the gas needle drops like a rock. i know bigger tires changes the math a little.

lfhoward · **Posted:** Tue Dec 15, 2015 9:20 pm

I wish I knew of something obvious to check, but you have covered your bases extremely well. (Even checked O2 sensors-- nice work!) Here are a few other things I might try.

At this point I would try running some Lucas fuel injector cleaner through a couple of tanks of gas. Either that or use Shell V-power for a couple of tanks. The cleaners in it will strip away any gunk in your injectors and fuel line that may be interfering with efficient combustion.

What kind of plugs are you using? The Autolite copper cores I installed last Friday have made a positive difference in mine (maybe +1 to +2 mpg over what I was getting before).

Blow out the cobwebs. Accelerate strongly when merging onto the interstate so that the RPMs go above 4.5k. Do this a few times.

Any chance you have a restricted tailpipe? Check it to make sure it is not crushed closed (or nearly so). If there is a way to check for a plugged cat, it might be worth checking.

Check your tire pressure. Low pressure could be sapping mileage.

I use a Scangauge II to keep tabs on my mpg while driving, so I can alter my behavior if how I am driving in any particular situation is not very efficient. I coast as much as possible.

I hope one or two of these suggestions helps!

PALiftedKK · **Posted:** Tue Dec 15, 2015 9:31 pm

Thanks lauren! I forgot to mention i run high psi. Gage knows this well haha. 42 psi is what im currently sitting at. I do lucas fuel stabilizer and injector cleaner every other tank.

Also just got cleared as far as emmissions goes. Not sure if that mean anything with plugged cats.

I also use oem plugs. Litterly walked in the door and asked for em. What a waste but i needed them right there and then.

Maybe the engine oil was a bad batch or something like that.

I hope this isnt an early sign of her demise :5SHOTS:

Bmxer524 · **Posted:** Tue Dec 15, 2015 11:13 pm

I normally only see about 200-220 miles per tank. Sometimes a tad more if I'm pure highway. That combined with about 17 gallons of gas gets me ~12mpg. What kind of driving are you doing? Winter doesn't help (not that we can really say we have a winter yet...).

PALiftedKK · **Posted:** Wed Dec 16, 2015 12:40 am

Bmxer524 wrote:

I normally only see about 200-220 miles per tank. Sometimes a tad more if I'm pure highway. That combined with about 17 gallons of gas gets me ~12mpg. What kind of driving are you doing? Winter doesn't help (not that we can really say we have a winter yet...).

Thats seriously my issue. Like down to the exaxt mileage. On the highway, theres no reason why we shouldnt get 17 mpg or more.

I usually do 65% highway. The rest is questionable. Half the time i spend looking at obd data and taking apart. Not as bad as dan though. Sorry man...

Thinking about it more the cats may be clogged. The only evidence i have without tapping into the exhaust is the short and long term fuel trim.

When the jeep idles it shakes the whole jeep. Obviously not a misfire, no cel or diffrent cylinder tone.

lfhoward · **Posted:** Wed Dec 16, 2015 9:44 am

I think the shaking at idle might be par for the course. When mine starts up and it's cold, it does the same thing. Once it warms up, it smooths out.

Well, one other thing that might be worth trying is to disconnect the battery overnight to reset the Jeep's computer. It will have to re-learn your 4.7 throttle body and your driving style, but if there is any kind of weird adjustment to the fuel trim that the Jeep had been caught up in doing, it will be gone.

https://www.youtube.com/watch?v=nn2FB1P_Mn8

lfhoward · **Posted:** Wed Dec 16, 2015 9:48 am

Another quick question:

Did the reduced mileage begin to happen right after you relocated your oil filter & installed the oil cooler?

Not sure how that could be related, but I was just thinking about whether the engine mod and the reduced mileage coincide. Correlation is not necessarily causation, but am curious.

tommudd · **Posted:** Wed Dec 16, 2015 4:38 pm

Winter gas sucks of course have you thought about that?

PALiftedKK · **Posted:** Wed Dec 16, 2015 7:18 pm

Well as i started her up a moment ago she started and the second after she turned over she started to spudder. Turned her off and started up again. Sounds like a fuel delivery issue...

Tom, i was told recently they dont do winter gas. Since theres so many cleaners and ethanol in the gas.

Lauren, the remote oil filter is being installed tonight before i change the oil tomorow. Theoretically this mod would reduce pressure if done properly thus increasing mileage "on paper" and not noticeable at all in practice.

Edit:: and after 4 times starting the engine i have no chime... Looks like im heading into 2008 kk issues... :5SHOTS:

Gageraid · **Posted:** Thu Dec 17, 2015 2:23 am

Trust me, they definitely do use Winter gas, especially in the tri-state area.
My winter gas mileage is almost 3mpg less than the warm months.
Check that your throttle body is clean and no oil on the IAT sensor.

Troublesome kk...

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