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Jeep Cherokee help

Thursty

Thursty

Well-Known Member
Location
Green River
He guys.
I have a '95 Jeep Cherokee with about 123k mike on it. The Jeep is running/idling rough like its mis-firing or starving for fuel. It also "bucks" pretty bad driving down the road and is lacking power. Also, it is NOT throwing a check engine light. Here is what I've done so far:

new plugs, wires, cap, rotor, coil
timing and firing order are good
fuel pressure is good
replaced a weak #3 injector
replaced MAP sensor

I have a friend here in Moab whose '95 Cherokee is doing the same thing, also with no luck finding a cause. Any help would be appreciated. Thanks in advance.

Mike
 
redneckhatton

redneckhatton

Member
Location
Springville Utah
it sounds like it might by your idler needs to be adjusted but not sure its just what it sounds like to me though but you can try it and see what happens and it wont cost anything unless you have to replace that.
 
bull7467

bull7467

The Yellow Jeep Squad
Location
American Fork
Do you have any loss of oil pressure? I had one that was similiar and the cam shaft was bad cylinder 5 and 6 valves were not opening all the way. Compression was fine on both. The way we found it was watch the valves with the cover off.
 
Herzog

Herzog

somewhat damaged
Admin
Location
Wydaho
I'd consider the CPS (crank position sensor) and/or TPS (throttle position sensor).

Try cleaning both of them up first. Usually the TPS just needs a good cleaning. There are documents out there that show how to test both of them. I remember having to run an extra ground wire to my TPS for some reason a long time ago. I can't recall why.
 
Silly Willy

Silly Willy

Well-Known Member
Location
American Fork Ut
Herzog said:
I'd consider the CPS (crank position sensor) and/or TPS (throttle position sensor).

Try cleaning both of them up first. Usually the TPS just needs a good cleaning. There are documents out there that show how to test both of them. I remember having to run an extra ground wire to my TPS for some reason a long time ago. I can't recall why.
Click to expand...

What I did to check the TPS was take off the black tube (the air intake) and put my hand over it, (letting in less air) to see if it made any difference, sure enough it started to idle smooth again. Replaced the TPS and haven't had a problem..

Just a suggestion.
 
RockMonkey

RockMonkey

Suddenly Enthusiastic
I'll second the crank position sensor. Get one from the dealer, parts store units are junk. If you don't need one now, you might as well buy one anyway because you'll need it soon.
 
O

outlaw_offroad

XJ Pride!!!
Location
North Ogden
How is your catalytic converter? May need a 3 lb hammer massage to clean the plates up.

I am not sure that the CPS is the cause. My experience with jeep engines is when the CPS is bad, the truck won't start. CPS can be a pain to change as well.
 
Herzog

Herzog

somewhat damaged
Admin
Location
Wydaho
Agreed, but CPS can cause rough idle and other problems. But most of the time you're right though, it just causes the vehicle to not run.
 
RockMonkey

RockMonkey

Suddenly Enthusiastic
outlaw_offroad said:
How is your catalytic converter? May need a 3 lb hammer massage to clean the plates up.

I am not sure that the CPS is the cause. My experience with jeep engines is when the CPS is bad, the truck won't start. CPS can be a pain to change as well.
Click to expand...

A plugged cat usually causes lack of power. They usually idle just fine. My WJ stumbled and ran crappy when it had a bad CPS.
 
Tan Comanche

Tan Comanche

Desert Speed Shock Tuning
Location
Santaquin
I've got an extra (working) Crank Positioning Sensor, if you would like to give that a try. Also, I have a gauge to check your fuel pressure.

My 4.0 was doing the same thing this week. I had 12 psi on my fuel rail and my injectors were clogged. So I cleaned injectors, installed new o-rings, all new vacuum lines, and replaced all the rubber fuel lines. It works amazing now. It actually idles and accelerates.
 
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