Help me diagnose my wifes jeep

OK, I have an 88 that is a trail rig and is of course renix, so I know all about that system.
My wife on the other hand has a DD 93. It is doing something really wierd which I may have posted about before. After driving at hwy speeds for no less than 45minutes, it starts bucking and running like crap. Let it sit for a while and all if fine. Did it over xmas and then today, thats it.
If just driving around town it is fine. Of course no check engine lights, no codes, nada. Of course it only has the idiot light dash so that does not help matters
So I have narrowed (not really) it down to:
CPS
TPS
O2 sensor (is there more than one?)
fuel filter
fuel pump
fuel pump relay
distibutor
distributor sensor (or whatever you call that thing)

If anyone has any thoughts or has had a simlar problem, I would love to hear it. I find it odd that it takes so long to become a problem.

interesting... My '88 does the same thing, but only if I've been hammering on the throttle for a while (over 75mph), it also only happens after about 30-40 minutes of continuous driving. Runs fine if I take it easy...
Does it feel like it's sputtering/bogging?
I've been blaming it on the occasional tank up at different gas stations...

I pound the heck out of mine for the trip to work 15-30 minutes and it's usually fine...

:dunno:

I'm usually happy that it fires up every morning

Hmmm....just a guess, but i had an older car that did the same thing and the problem was the o2 sensors...(2 of em)....i dont know about the older jeeps but my 2000 has at least 4 at the bottom of the manifold. Good luck

Gil BullyKatz said:

interesting... My '88 does the same thing, but only if I've been hammering on the throttle for a while (over 75mph), it also only happens after about 30-40 minutes of continuous driving. Runs fine if I take it easy...
Does it feel like it's sputtering/bogging?
I've been blaming it on the occasional tank up at different gas stations...

I pound the heck out of mine for the trip to work 15-30 minutes and it's usually fine...

:dunno:

I'm usually happy that it fires up every morning

Click to expand...

That's it exactly. But it only does it for a second like bubcking. Then at idle once you pull over it runs really ruogh, sputtering bogging.

Similar, but mine does it for as long as I hammer it.
When it happens (usually when trying to pass someone) I usually throttle off and it settles back down to running fine... If I come to a stop, it's also fine.

It's an old tired engine pushing 33's on 3.55 gears at 70mph+
I'm just buying time till the project engine's done

Good Luck

Since you don't have any codes I'd start checking the stuff the computer doesn't monitor like the ignition (coil, plugs, wires, cap, rotor).

Probably a dumb question, but have you checked your CPS? Not the sensor proper, but look at the cable.

It runs right near the exhaust manifold, and sometimes they like to commit seppuku by leaning against the manifold and melting thru. I'm looking for an effective heat sleeving that will work.

I find it interesting to note that my last four CPS replacement were caused by melted wiring, and I just had to splice in a new pair of wires to make it work. I gotta find a better way...

5-90

5-90 said:

I find it interesting to note that my last four CPS replacement were caused by melted wiring, and I just had to splice in a new pair of wires to make it work. I gotta find a better way...

5-90

Click to expand...

Fiberglass sleeving?

5-90 said:

Probably a dumb question, but have you checked your CPS? Not the sensor proper, but look at the cable.

It runs right near the exhaust manifold, and sometimes they like to commit seppuku by leaning against the manifold and melting thru. I'm looking for an effective heat sleeving that will work.

I find it interesting to note that my last four CPS replacement were caused by melted wiring, and I just had to splice in a new pair of wires to make it work. I gotta find a better way...

5-90

Click to expand...

Thats the first thing I check actually. The Cps is old so I am thinking it is a likely posability. I am trouble though but the fact it takes 45 minutes for symptoms to appear.

Been there done that.
I had the same problem with mine and its a 97.
Make sure you have fairly new or at least working condtion 02 sencors.
I then changed my plugs, wires, cap and roter. She runs great now. Also make sure the air filter is clean. Some times all they need is a little TLC. Oh and dont use the Bosch plugs. Every XJ I have put them in ran like crap after.

I'd start by cleaning the throttle body & checking all vacuum lines for leaks.

Any other thoughts from anyone

5-90 said:

...It runs right near the exhaust manifold, and sometimes they like to commit seppuku by leaning against the manifold and melting thru. I'm looking for an effective heat sleeving that will work.
5-90

Click to expand...

Try the thermal sleeving sold by Summit. I first got some for my project Mustang. I converted a 65 to cable clutch and the cable runs right btw two header tubes to avoid bending the cable. I haven't had a problem with it. Its been done for 2yrs and has about 10k mi. on it. The brand is Cool It/Thermo-Tec and the stuff is called Thermo Sleeve. Claims to to reflect up 2000* I got mine in a size larger than I needed and wrapped it double. I'm going to replace my CPS soon and use it. I'm going the shrink wrap the wires individually, then together, then cover it with the sleeving. Seems like overkill but the CPS is such a pain that I figure its worth it. Besides, I can always salvage if I need to replace the CPS and I had it leftover from my 'Stang project. I can get you exact P/Ns if you need. It looks like I can wrap what I have around my wires about 4x then zip tie it so it won't come apart.