Ok, so over the last four or five days I have been getting around in the Jeep. I have put some miles on her. I dumped a bottle of Berryman's fuel injection. cleaner into the tank and filled it up. The CEL went away almost immediately after this. I have yet to get the CEL to come back. The CEL code was for po171. According to the factory service manual, that code means that there is a lean condition that causes the computer to overcompensate which results in a rich condition.
I'm not sure exactly what the Berryman's did; however, I did notice when I first bought the Jeep that the fuel gauge would wander back and forth a lot. Imagine the needle slowly moving from empty to three-fourths of a tank or more. That wandering did minimize but it's still there. I checked fuel mileage using the odometer reading and amount of gas needed to fill up. After the Berryman's, which I've used a little over a half tank of fuel, has increased my mileage from around 8 to 10mpg.
My thoughts are that the fuel float is messed up and possibly debris in the tank??? i don't know. That was just a thought and a question to you more experienced Jeep enthusiasts. However, on the last fill up yesterday, as soon as I pulled into the station, white smoke started coming from the engine bay. I pulled up to a pump quickly and shut it off. I went to open the hood and look inside. There wasn't anything I could see wrong. NO more smoke or anything. I fueled up and looked again inside the engine bay and didn't see anything.
After this, I drove away but noticed that the engine coolant temps rise more quickly. Yesterday, I wanted to inspect and replace the the differential fluid. I took off the cover, which was not easy, and inspected the ring gear and the spider gears. It looked okay to me. I was looking for heavy scarring or chunks I missing. I didn't see any. The fluid was only slightly dark but not too bad. What worried me is the pan was littered with glitter. Little tiny specks or flakes of metal shavings. I have a few pics I'll post later.
I read up about which fluid to put into the diff. However, it was hard finding something. One of the oils I looked up was the Lucas oil 75w-90 synthetic. It says Gl-4 and Gl5 rated. However, I saw multiple people review the oil on Amazon that it put the oil into their WJ's and XJ's and everything was fine. One person even edited their review and said after 50 or 100k miles that the rear end hadn't exploded or anything. I hope this oil is ok. I have a RWD model and I am pretty confident that there is no locker so I probably don't need the 4 oz. friction modifier but I added one anyway from LubeGuard. I love their stuff. Do you guys have any experience with them? What about Lucas or Amsoil Synthetic in the diff? Yay or nay? Which friction modifier do you guys use? Does it matter?