Having a few problems with my jeep

my transmission shifts at the proper times… but if i need to pass someone the transmission wont downshift to give me more power… i checked the kickdown cable and it seems to be working right… another problem i’m having, is i have to have the tps disconnected for it to run properly, it started running terrible a while back… it was idling at about 500rpm maybe even a little lower, and running so rich that the floor under the tailpipe was black within 30 seconds of run time, i changed the tps and it fixed it for a short time, but it acts now and then running poorly… but ever since i unhooked the tps it hasnt done it once… any ideas would really help me out… thanks

What year model is the Cherokee?

Check the wiring & power supply for the TPS.

In addition to causing running issues w/ the engine a TPS problem messes with the transmission like nothing else. Think about that - you mash the throttle down to pick up some speed. How does the transmission know?

1999 cherokee sport

thanks for the info, i’ll check the wires and see if they’re in good shape… whats the power supply for the tps though?

The typical TPS has 3 wires - 5V reference, ground, signal. The 5V should get right around 5V with the key on. The signal specs vary a bit, but figure something like .5V at closed throttle to 4.5V at WOT. The increase in between should be perfectly smooth as you open the throttle.

Better to put it on a scantool but you can start with a voltmeter.

Autozone’s online repair manuals might give you specifics for your Jeep along with wire id.

i followed the wires back to a big plug, in a metal box that kinda looked like a computer… the wires were fine i moved the plug around real good, plugged the the TPS back in, said a prayer… and its been running perfect since i did that… so maybe there was a little corrosion on the contact point… but thanks for the help i really apreciate it

Its probably a good idea to pull the plug out again, spray it out really well with some electrical contact cleaner (any auto parts, hardware, electronics store), smear a thin coating of dialectrical grease on the female end of the plug and on the little rubber gasket and plug it all back in. That should ward off the demons. If it comes to it, you can usually get a replacement direct fit plug.

Thanks for reporting back - always good to hear how things are turning out.