Fix one thing and something else goes crazy. Not sure if the cold weather coming is precipitated this or not.

Jumped in the Jeep last night to get home, while driving - like a grandma these days with the gas prices through the roof - the beast started having trouble shifting gears.

First it wouldn't shift down, and then it was searching. Then the CEL came on but I haven't read the codes. Today I got in to drive it around the block and it wouldn't shift out of first gear. I didn't try to drive too fast so I don't stress anything worse.

The only things I've done lately were replaced the turn signal relay yesterday, and about a month ago I changed over some of the transmission fluid with Valvoline high mileage.

I don't know what kind of service the transmission has had. I bought it at 85,000 miles about 8 years ago and it has 144,000 miles on it now. I've never flushed the transmission.

About two years ago my engine blew up. Since the transmission is cooled by the radiator, I'm worried the fluid may have burned out at that time. It definitely stunk bad when I changed it.

So yeah - probably worse case scenario. But I've read great things about these AW-4s being overbuilt.

In the mean time, can anyone recommend anything else - like checking the vacuum lines (which ones even), doing a complete flush (maybe some burnt out fluid is gumming up a valve), or anything else that is a good first round of checks before dropping a bunch of cash I could desperately use on something else.

As always guys, thanks!

 

https://www.cherokeeforum.com/f2/free-quick-fix-41821/

Try that.

But I would get those CEL codes as well could give some more insight. Go to O'Reileys auto zones reader wouldn't read my 99

 

That's an interesting write-up. I checked up on the kick-down cables and they seem fine. I've actually been working around them since I stuck my air-filter right onto the TB but it was interfering with the cables a bit. Its on my "to do" list to get a spacer or a 90 degree turn so I can get a little bit of distance between everything.

So along those lines though - of the transmission not being mechanically broken - I checked the voltages of the TPS.

With key-on but engine off, I get a reading of 2.17v from my digital multimeter.

With engine on at throttle, I'm getting 2.27v.

With throttle about 25% open, I'm getting 2v.

WTF? That can't be normal.

So I need to figure out what the normal range is, and then whether something is grounding out somewhere (shouldn't be) or I need to just go ahead and replace the TPS.

 

Those readings are way wrong! Another possibility, is the detent valve in the valve body may be stuck which would keep it in first gear.

 

Welp, TPS.

Drove over to the car shop, which was a real adventure to drive through rush hour with one foot on gas and the other on the brakes so the engine wouldn't die out... while also only going 25mph and 4,000rpm.

Picked up a new TPS and voila! Not only is the idle smoother than its ever been, but the transmission is shifting exactly on time and when I hit the gas I get a real seat of the pants ride.

Since I stroked my 4.0, I've been worried something was wrong because it's been sluggish. I punched the gas on a side street and the exhaust just screamed and it lurched forward! It was awesome!

I really hope this fixes the 12mpg Ive been experiencing on the highway!!! I wish I knew about the dang TPS sooner.