stumble stumble

Hi,
Ive got a problem come up with my jeep. Last week i was driving down the highway and noticed a stumble from the engine. Then a little while later as i was approaching home it done it again and again and again in pretty much quick succession before dying on me. I opened the hood, gave it a good looking at, before closing it again and driving home the rest of the journey without problem. My brother in law came over and had a look and gave it a real good thrash in neutral. It seemed fine and was idling fine.

Last week i drove my car every day the 6 miles or so to and from the train station without incident. (however i did notice on one occasion that the idle was high, about 1100 which is something that it has never done before. then after about 1 minute it fell back to normal)

Yesterday it stumbled on me again. Basically it starts fine, sounds fine. But after about ten miles on the highway it just starts to play up. When i ease off the gas also when im in town is when it dies totally but again it takes some time before it starts to play up.

Now, fuel filter is something that i have seen can cause this but this happens when i run on petrol or gas and each has its own filter so i dont think its that in this case.

Also im probably gonna be taken this into a garage to have fixed and am just looking for ideas as to what the garage may say to me and what they shouldnt say to me!!!
Also i have searched, i just dont wanna say i think its this or that because im probably wrong anyway!!! So any simple cheap things to check or change prior to me taking it to the garage would be a great help.

many thanks

Post the year and engine of your XJ in the beginning of every new thread for best results.

I'd start by verifying fuel pressure. Easy to do and is pretty high on the "process of elimination" chart. Other suspects include the crankshaft position sensor and the ignition coil.

sorry its a 97 4ltr auto, runs on petrol or gas which run independantly of each other, but stumbles on both. Temp gauge seems fine. Idles fine, starts fine and no loss of power that i can tell.

dunbad said:

... runs on petrol or gas .. but stumbles on both..

Click to expand...

That would probably rule out fuel supply issues.



Clean the throttle body and the Idle Air Controller.

Cleaning the Idle Air Controller (IAC) :

Purchase Throttle Body cleaner spray, not Carburetor cleaner.

1. Remove the Throttle body from the intake manifold.
2. Remove the IAC with a TORX 15 driver (2 bolts)
3. Gently wiggle out the IAC from the throttle body
4. Clean the IAC with throttle body cleaner (not carburetor cleaner) Use cleaner, a rag and a toothbrush. Be gentle; don’t twist or pull on the pintle as it is fragile and can be damaged easily.
5. Also clean where the IAC seats in the throttle body with the same throttle body cleaner
6. Reinstall IAC, the Throttle body, and check idle quality.



Suspect the Crankshaft Position Sensor, and the Coolant Temperature Sensor.



.

Hi
just an update to this. I cleaned the iac, changed leads, dizzy cap and rotor. It still just randomly dies on me. But has started fine from a cold engine. A garage told me there were no codes thrown.?? although this wasnt a dealership garage. The only thing thats changed now is when it starts to stall on me, i get the skim light come on. Also its kinda hard to restart once its started playing up. it turns over but doesnt start. When its turning over the revs show zero. Does this make any difference?

also when it cuts out on me the revs simply drop like a stone. But like i say, its random but has only happened on a hot engine. Yesterday i drove 20 odd miles with no issue. Then last night i had difficulty making a one mile trip! i asked the garage to check the cps but the guy told me he didnt have time!!! i shall be taking a closer look at the tps thanks to a great thread by the chap above this post. but could the issue be the key?

The "chap" in question is tim_MN. Well done sir, that is a great post! hopefully i can put it into practice. But at 250 us dollars for a new tps from jeep uk. i hope it aint the tps!

Just to update this, it was indeed the cps, crank position sensor. Heat had an effect as it would not cause issues until the engine was up to temp. I disconnected the cps and plugged the same one back in and it was still playing up. I done it myself and it was a sinch. I didnt disconnect anything but used a 3/8 swivel head wrench, a uj socket and a couple of extensions