I was forced to becuase my started commited suicide today. So I gave it about a 30 min disconnect when I was replacing the starter. Now I get this stalling even worse now.

 

Champion coppers are the way to go, the plat plus 4's will make it run worse IMO. some motors like it, these dont lol

 

Oddly enough, I have gone from 12mpg to about 16mpg slowley...not sure why but my mileage is slowley increasing.

I have been running shell gasoline too for the past four tanks...perhapes my engine is fouled up from running rich from a bad o2 sensor? I ran my engine for a few thousand miles on a bad 02 because I didnt have the cash to fix it all.

 

Yea i fixed all my o2s. It didnt help me any.

 

Flexplate. I know it sounds crazy but it might just be your problem. Mine was completely center punched and still ran. Just didn't have much power and terrible gas milage. Passed DEQ just fine, no codes. Took it to two seperate shops and both could not find the problem. Tried evverything that everyone here is suggesting and finally listened to the "old man". Check your flex plate. Get a mirror and a flachlight pull your inspection cover and take a look. Cost, nothing but time. If it is the problem, Priceless!

 

My Jeep has power just really bad blow by and horrible gas mileage compressioned checked each cylinder and got 120

 

if your compression is 120 on all the cylinders its probably not blowby.

 

Hey 4.0... I am going to have to say with your odd throttle response that it sounds like you have a TPS issue... and especially if it got worse after you had the battery disconnected... cause that would cause the ECM to learn off of the messed up signals of the TPS and would make it run even worse than it did before you reset of the ECM.... If you can find a 4.0 in the JY hit that up... shouldn't cost too much for a TB from the JY...

 

that is the best avatar /\

 

ive slowly read over this ,an i to am having same issue.....if most of us are having same issue,maybe bad gas wht gas are u runnin high med or low an dont forget about all that ethanol there pumping into the gas now

 

i have read through this but i have 32x11.50s with a big bumper and tire carrier on the back is 12-13 really not normal for a 4.0 and these extras?? i got it with the tires and i didnt ask about the mpg cuz it was exactly what i wanted haha and i kinda figured that it would be about there...

 

No not really. THere are a few out there getting bad MPG and nobody really knows why.

 

What is the compression supposed to being heard 120 is super low and it should be around 150 what else would cause oil to come out of my oil cap and valve cover? Also smells like gas when I get on it all my fuel parts and sensors are new

 

I think compression is 130-150. Maybe 120-150. But 120 is low in my opinion. I don't know anything though.

My MPG has gone up to 17-18 without me trying much after it was around 12-15 in the winter and I was trying my best for good mileage. It must be temp related. I've done nothing to it. It seems like the colder it was the worse my MPG was. As it warmed up, my MPG gradually went up.

 

The oil problem means you either have a clogged CCV System or bad blowby.
The gas thing when you get on it could be a rich condition at WOT or a bad cat.

yupp that has a huge effect on gas milage colder air=denser air. Denser air means the PCM injects more fuel per combustion cycle to keep the A/F ratio within acceptable limits....this also means that on the coldest days you make the most power. The warmer it gets, the less power you make and the less gas you use.