Hello everyone

I back probed the the middle wire of the TPS with key turned to on, and I turned the throttle with my hand to wide open position. The reading I got at fully open was 3.5. Is this too low? Does it suggest a problem with the TPS? When I checked the other wire it read 4.9

thanks

 

That does seem rather low.

 

I just checked again with engine running. As the engine was getting hot the readings starting becoming very erattic. Once it got to operating temp the readings stayed at .75 . Could this be a heat related issue? Could it be related to CPS or oil pressure sending unit, or oxygen sensor ??

 

Sounds like a bad TPS to me.

 

The important reading is if the voltage varies evenly in proportion to moving the throttler

 

Update: I tested the ground at the back of engine block and was getting fluctuating voltage. I cleaned it a little, the jeep didn't stall when driving this time. It might be the ground was effecting the TPS?

 

A bad ground will definitely affect things, although a bad ground would make it read higher than normal.

 

I replaced TPS and cleaned the ground. The jeep still dies exactly 10-15 minutes after starting the engine, every single time. When it dies while driving, I have to wait for a few minutes before it will start again, and then it drives normally. When it dies in idle without driving upon start up, it can be restarted immediately without issue, unlike when it dies while driving. Any ideas what is going on? This is driving me insane

 

Bad O2 sensor? You could try unplugging it and see what happens.

 

Though it could likely be the CPS (Crank position sensor),you should check the resistance with a VOM between terminals per the shop manual - you'll need long extensions between the socket and ratchet to reach it

 

CPS could be failing when it gets hot. The resistance test wouldn't apply for his 1992 though. Need to figure out if you're losing spark and injectors when it dies.

A quick test of the CPS would be key-on, wait for the fuel pump to stop, turn key to crank and see if the ECM sees cranking and runs the fuel pump again.

 

Most definitely sounds like CPS. Measure signal DCV. Should be about 5.0 if you turn it REAL slow by hand and KO, maybe a little over 2.0 if cranking (any volts it'll start & run, 0.0 volts it won't).

 

Yes. as they get old the CPS becomes VERY sensitive to heat. However, the Haynes Shop Manual, 2005 edition page 6-20, does state a resistance test for the CPS:

 

OP has a 1992, so yeah a check that it's not shorted makes sense. You can look for voltage while cranking with the meter set on a/c.

 

Solved: https://www.cherokeeforum.com/f2/mys...earned-275833/