Newbe with 94xj Please Help

[xsubarudude]

Newbe 94xj jerk hesitation Please Help

Hi everyone.
Hope I can draw from your experiance.

I recenty got a 94 xj country 4.0 HO

all in all, the jeep is in very good shape.

there is one problem that scares me.

The real problem is a sharp repeating "jerk" or "stop-bump" or "hesitation"
when coming to a stop at a light , or coasting at a crawl and also while stoped with it in "drive".
It is constant, from the moment i start it and while sitting in traffic and till the time i shut it off at the end of the day, reguardless of engine temp.
There is also very slight idle hesitation when in neutral.

The scary part is , it is getting worse,. Not sure if it is weather related or it the problem is just worsening on its own.

I do know that the XJ has a 160 degree thermastat.

Does anyone have any experiance with this problem?

Thanks

 

[MG_43]

Get rid of the 160 thermostat, need a 195 for it to run properly, computer thinks its still cold.

 

[xsubarudude]

still,,,it has been fine up intill this month.
It does it at any temp even when i start in the morning,,, that surly can't be normal.

could it be that the O2 has been corrupted by the constant lower temp?

 

[Rocketman]

It could be so many things. MAP sensor, vacuum leak, plugs, wires, cap, clogged CCV, o2 sensor, leaky intake manifold, fuel pressure regulator, injector. Start a checking process of all systems. Do vacuum checks first. Install a 195 thermostat. Pull & regap all plugs, check distributor cap for carbon arcs or cracks, Check ballast resistor too. Basically open the hood and make everything spec.

Clean all grounds too and reseat connector for crank position sensor.

Did I forget anything? :laugh3:

 

[xsubarudude]

Right,,
got the 195 thermo today.
Also i cleaned the Throttlebody ,, it was horrible! it was so incrusted i had to take it off to clean it
( makes me fear that mayby my valve stems may just be as bad)

i will install those tomarrow. and check all the plugs and distributer and ccv

thanks for all the input


:looney:

P.S. come to find out, my parents 04 grand does the same thing,,,, maybe it's just a "Jeep Thing" and we're not ment to "understand" ;P

 

[xsubarudude]

Update:

replaced plugs,distributer and rotor cap*.>>> Major improvement ! much smoother idle.:sad1:

relaced fuel filter >> even more of an improvement!!
Running very smooth now!:sad1:

*Had to exchange the cap for a higher quality one because
i noticed an imperfection in the new Auto-Zone cap befor i even got out of the store with it!

 

[xsubarudude]

PEICE OF AUTO-ZONE ****. FILTER LEAKING!!!!!!!:smsoap:
Had to dig the old filter with 157,000 miles on it, back out of the garbbage can and reinstall it!

Can notice idle differance. going to have to buy a quality filter from somewhere.

Man! How hard is it to make a simple product with quality ?

NEVER buying nessasary parts from Auto-Zone again!

 

[Shortstraw8]

The big thing on mine was CCV & Fuel pressure regulator works perfect.