1989 jeep xj 4.0 has major power loss but randomly gets power back and drives normal
 

Basically exactly what the title says you'll have your foot to the floor and it will barely be moving but then randomly it'll start driving to completely normal and then it'll stop doing it and start doing it the whole time you're driving ..

It's a 1989 Jeep Cherokee with the 4.0 liter an automatic transmission 242 transfer case.

It's got a new fuel pressure regulator and a new fuel pump and fuel filter.
Help!

I had the same problem with my 94 Nissan pickup. It turned out to be the throttle position sensor (TPS). Is your check engine light on?

It's got a brand new throttle positioning sensor that is adjusted to exactly what it supposed to be and it was running fine with that sensor for 3 weeks but now it's acting up doing something completely different and no check engine light is on

Same exact peoblem on my 95 and it was the bank 1 o2 sensor below the header.

Welp at the same time we did the throttle positioning sensor we did the upstream o2 sensor right by the header so it is also brand new within 3 weeks

Also has hey new crankshaft positioning sensor idle air control valve has been thoroughly cleaned and the throttle body and intake have been thoroughly cleaned. Could it be the catalytic converter?

Yepp! Stopped up cat will cause backpressue issues.

woooeeyaaahessir
 

yes sir, had the same problem on my 89 xj pioneer. was the tps on the tranny. about 200 dollar fix(if you find an honest transmission place). good luck buddy!

KC

i quote my own replies due to the alcohol and all.... heck i forgot what i was saying

Yes. It could be clogging up? Here's how to test for that.



CRUISER’S VACUUM TEST FOR EXHAUST RESTRICTION
Your vacuum gauge should come with an instruction booklet outlining the procedure. Hook the vacuum gauge up to a source on the intake manifold. Start the engine and note the vacuum reading. Usually 17 to 21 inches of vacuum. Throttle the engine up to 2,000 to 2,500 RPM for 20 seconds or so and the vacuum reading should stabilize to the same reading you got at idle. Let the throttle snap shut. The vacuum reading should shoot up about 5 inches of vacuum higher for a second and then come quickly down to the original reading. If the vacuum reading stays high and comes down slowly with jerky needle movements, you have an exhaust restriction.

TPS is on the throttle body. NSS or VSS is on the tranny.

Also, you aren't going to have to worry about a check engine light, because your Jeep doesn't have one. :) (As long as the original Renix engine management system is being used :P )

Thanks cruiser! And no check engine light I figured! I'm work in a shop but wasn't at work to get opinions! It's my brother in laws! I guess we will find out!

I'll list new parts
O2 sensor
Tps tuned to spec
Cps also "tuned"
Iac thoroughly cleaned
Fuel pressure regulator
Fuel pump and filter
Alternator
Starter
Plugs cap rotor wires

All this was done previously not for this problem. Within 1-3 months ago

Do the vacuum test.