So I was driving per usual today and my 93 xj started to jump around a little. I looked at my rpms and it wouldn't go above 3k rpms while it was either in 3rd or 4th. The needle was just bouncing around 3k like it wanted to go higher but couldn't. And yes, ik they're supposed to shift around 2-3k rpms but I just found it interesting it wouldn't go higher. I think it will still shift into 4th (I wasn't counting gears while driving so idk). It's a 4speed automatic, and it's a 2wd sport so y'all mechanical geniuses lmk what it might be

vid is short bc of mb restriction but yall can kinda see the needle just jump around and not go higher

 

Check your neutral safety switch: some (older) vehicles will rev-limit the engine to 2500-3000 RPM or so if it think it's in neutral so you don't drop it into neutral at a higher RPM. Obviously you're not in neutral, but the switch may think you are.

Try blocking the wheels, setting the parking brake, then with the engine off disconnecting the connector to the on the shifter linkage on the side of the transmission and measuring continuity with a multimeter to see if the expected contacts open/close as you shift between the gears (you might need two people for this). Be absolutely sure that the car won't roll while you're working under it by blocking at least two wheels in both directions.

 

It will go above 3k when in 1st and 2nd and I think 3rd, I'm pretty sure it's just 4th that's not going above 3k, would that matter at all or could it still be the safety switch

 

That throws my theory out. When it won't rev to higher ranges in the higher gears, is it running out of power? Have you done a compression test and does it have any pending codes?

 

Check your fuel pressure and for any intake/exhaust restrictions.

 

Might be worth checking your catalytic converter for excessive back pressure. You can use a vacuum gauge or back pressure gauge.

https://axleaddict.com/auto-repair/H...ytic-Converter

 

it's not running out of power cuz I can keep it going at 3k, it's just the rpm's jump around a little bit so u can feel it losing and gaining power in little spurts. And idk what a pending code is unless ur talking about an OBD reader, which I don't have

 

A 1993 model is before OBD2, so typical code readers won't work anyway. You can check for OBD1 codes without a reader:

https://www.fixjeeps.com/jeep-check-engine-codes.html

 

this is actually really helpful and I didn't know older cars had this, thanks!

 

Idk how or why but today she ran fine and did good, I did the thing for the codes and all I got was code 55 so everything is fine I think