So I bought a 98 Jeep XJ and after purchasing it had a problem show up that I'm not sure what it is but basically when it sits for a bit then starts, it won't shift into overdrive, but if I drive and then pull over once it hits 3rd gear and restart the car, it shifts perfectly fine. I honestly have no clue what on earth the problem is and am wondering if anybody has any ideas about what is going on.

 

Check you XJ's transmission speed sensor. That may be the culprit. There's a few Youtube videos out there for checking and replacing.

 

Not the speed sensor because if that fails, you won't upshift at all and I've never seen one fail. The most common causes would be either the brake switch, bad solenoid, and possibly the TPS. The brake switch is less likely on a 1998 as it's a better design and you'd notice the brake lights staying on, whereas on the older Cherokees it was a separate switch that tended to get loose and the only other symptom would be the cruise not working. The TPS, you'd probably noticed other shifting issues. The solenoid is fairly common and you can test it's resistance from the connector in the engine bay. The set of 3 solenoids are around $70 on Amazon and can be replaced by dropping the transmission pan. It's not a hard job, just messy.

 

When was transmission fluid last changed? Is it low? If it's a little low, then once it warms up your symptoms may go away until cold again.

 

Sounds like a tired transmission solenoid. When it's cold, it's sticky and doesn't engage for overdrive. Restarting the engine warms it up just enough to free it. Check the solenoid pack, it's a common failure on the AW4. A fluid and filter change might help, but the solenoid is likely the real culprit.

 

I'm not sure how long ago it has been, but it looks to be pretty new fluid

 

Forgot to mention It got a little bit low, but I topped it up again and it still has same symptoms.

 

how hard is it to change the solenoid?

 

The speed sensor is what tracks the vehicle speed though correct? Because the Jeep is regeared and on bigger tires and my speedometer is way off and I'm thinking that it might have something to do with it possibly?

 

Had a similar problem on my 98 jeep aswell,I ended up wiring in a new tps female connector and iac female connector.Also make sure you have a good quality tps sensor(mopar preferably).As well as proper kickdown cable adjustment.I have noticed alot of other jeeps cable(the pintle part where the cable protrudes)is right after the fuel rail

 

Interesting development, I just redid the head gasket and it is now not an issue? Since redoing it it has only done it once and nothing since, it did sit for a month while I was working but so far it hasn't been doing it constantly.