Revcwall

Guys hopefully you can give me a plae to start with this one. My Jeep has had the typical heat soak issue for as long as I can remember. I've been able to mitigate it no problem while wheeling by poping the hood and leaving it running while stopped.

However, last summer the wife was driving the jeep and I get a phone call from her saying it died while driving. The symptoms seemed very similar to the heat soak issue. She managed to get it home and I test drove it. Needless to say she was right.

The symptoms are as follows. Usually only happens when engine bay is hot. Summer or winter. Feels like it loses fuel gets a misfire and sometimes dies. If I throw it into neutral and shut it down and restart the problem sometimes clears right up. It has no codes. No MIL. Also it seems like it has a problem figuring out where to idle as when I come off the gas my RPM's usually drop unusually low then will bounce back. But not always?

Also I just got back from Easter Jeep Safari and while out there if I shut the jeep down for any reason while on a trail or after a highway drive it would not restart until I popped the hood and let it cool for at least 20-30 minutes.

I'm lost with this one cause it isn't throwing codes?? Any help or direction would be great. Thanks.

99xjclassic

TPS i hate em they cause a bunch of crap

Revcwall

Throttle Position Sensor?

Lyon

Check the tune up parts.

I believe you have the individual coil packs to each cylinder and not a cap and rotor with wires. You could have a bad pack. Check the spark plugs too. If everything is ok, look further in to the throttle body. Clean it. Pull the Idle air control valve and clean that. TPS could also be a problem. Sometimes you can have sensors out of range but not out far enough to throw a code. To go further, look in to coolant temp sensor replacement or crank sensor. It's one of those things you're gonna have to go through the motions and check.

tjwalker

What you describe DOES sound like typical heat soak, for which the 00-01 are very susceptible. If this never happens when the engine is stone cold but always happens after the engine bay is hot, this is probably heat soak; it is not uncommon NOT to have a CEL/code set with this.

Best fix is a timer on the e-fan which allows it to run for a while after the key is turned off. This reduces engine bay temperatures quickly and isn't hard to wire in. Louvers in the hood have helped others, but I like the e-fan timer. Some 00-01 owners have done both. SEARCH on this forum, Jeep Forum, Jeeps Unlimited Forum and NAXJA and you should be able to find all of the specifics.

Lyon

I only suggested to look in to further problems because he said he pops the hood and lets the heat out so it seemed like he had the problem there taken care of.

I agree with the heat soak problem. Hood vents are a great way to get heat to escape. There is also a bulletin about the #3 injector fix. But it doesn't always work from what I've found. But a combination will fix the problem.

1. Insulate and make a heat shield for around the injector
2. Hood Vents
3. Electric fan setup and time delay to run after Jeep has been shuf off. You can find programable ones on ebay.

Goodluck with your Jeep!

Revcwall

Just a few things. I know that I have the heat soak issue. This new problem is while driving it does this. Not after a stop. It will sputter, misfire and sometimes die while moving. This can be fixed by cycling the engine off then on again and it comes back to life as if nothing happened. These symptoms point me elsewhere. Like maybe a ecm going out? How exactly is a fan timer going to help when I'm already moving and the fan is cycling properly? I've got a heat gauge not just the dummy light and my engine doesn't get over 210.

I think the no start after sitting may just be the heat soak problem getting worse. I'm more concerned about the other problem. I'm not a new comer to forums and have gone through many threads after searching different terms but none describe the problem I'm having as described above. Please spare me your all newbs can't use search bs. If I would have found my answer I wouldn't have posted and asked for help.

tjwalker

1. Clean the idle air control and throttle body. They get carboned up over time and miles. This in combination can cause stalling

2. Test your throttle position sensor

3. Be sure you are not using Bosch spark plugs

David Ring

would the plugs really cause that or the ecu because I do have bosch plugs but had problem before that and I have lost about 800 chasing this exact problem buying pump after pump etc

tjwalker

David,

1. What are your EXACT symptoms? This is a very old post so we need to know what is going on with your XJ.

2. What do you mean by buying "pump after pump"? Do you mean you have installed multiple fuel pumps? If so, what brand?

3. A 1993 XJ is not normally susceptible to "heat soak". The most susceptible years for heat soak are 2000-2001.

4. I have had very poor luck with Bosch spark plugs for the XJ, no matter what engine or year. I like many Bosch products and am a big fan of the brand, but Bosch plugs for the 4.0 liter engine are not on my list of parts I will install. Some run okay with them but others do not. Why take the chance. Install some basic Champion copper plugs gapped to .035 on your 1993 XJ. For not much more than ten bucks and an hour of your time, you can eliminate this wildcard from your list.

5. Be sure that all other tuneup parts are fresh as well, including quality plug wires, distributor cap, rotor, fuel filter. Simple stuff first, always.

6. As for the computer, condemning this should be a "diagnosis of exclusion" meaning everything else is ruled out first. Most computers that are returned (on exchange) test out good.

David Ring

Thank you for the real response and lack of condemnation for reviving threads etc. I have replaced tps, cleaned throttle boddy and iac,new map sens,
plugs,wires,cap and rotor, 3x fuel pump finally settled with carter by the time I decided that was not the problem. It started as rough acceleration but it has gotten to where it will drive fine for about 2 minutes(gauged in time not miles because I do some slow mud crawling leaving my home) then start to misfiring through intake and exhaust,turn key off start back up does another 2 mins and then just starts getting less and less drive time till it finally just wont drive only misfire when you hit gas.