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Rough idle upon crank after warm shut off.

Achmed

Achmed

NAXJA Forum User
Location
Southeast US
This weekend at Tellico, several times, I had to shut the engine off to wait on the enormous line at Guardrail. A couple of times, when I shut it off (temp right at or slightly above 210), about 10 minutes later when I cranked it back up, the temp gauge was up almost to the next mark above 210. It idled rough and sputtered for about 10 seconds until the temp came back down to 210. It almost seemed like it was hesitating or missing for a moment. Any opinions? Injector heat soak possibly?
 
I have heard on the eaalier renix era XJ's that the Crank Position sensor can cause this....

I don't know if it carried over into the newer ones though....

Sometimes I hate being ASE certfied, it means I have an answer......
 
sounds like vapor lock in the #2 injector....I believe there was a TSB on that which entailed installing a heat sleeve over the injector(s)
My 89 did the same thing yesterday so I'll be looking farther into this myself.
 
This is a common problem with late model XJs, including my 2001.
My XJ does it a lot on hot days or when off-roading, especially after a long slow climb. It's so common that I carry a code reader for clearing the various misfire codes.
I have tried many things to cure including the solution below in the TSB below. I have had the best results by wiring in a switch and an adjustable time-delay relay that leaves the aux fan on for several minutes after the engine has been turned off.

I sometimes wonder if a fresh set of injectors would help prevent this problem. It was not a problem when the XJ had low miles.

A few weeks ago, I noticed that a friend's 2000 TJ had metal insulators under each injector, something XJs do not have. His 4.0 never has a hot soak problem.
I have not been successful finding the insulators online.


TSB
1803103 - 4.0L ROUGH ENGINE IDLE AFTER RESTART FOLLOWING A HOT SOAK
Date: 09/05/03 (supercedes 1802702 dated 09/06/02)
Model Year(s): 1999-2004

Description: NOTE: This bulletin applies to vehicles equipped with a 4.0L engine. This bulletin involves the installation of a fuel injector insulator sleeve.

Details: Customers may describe a 20 to 30 second rough idle following the restart of a heat soaked engine. This condition may be most noticeable when the engine is restarted following a prior 10 to 20 minute heat soak in hot ambient conditions of approximately 32 C (90ºF) or higher. This condition may be consistent with short city stop-and-go driving trips and can be aggravated by the use of fuel with a high ethanol content. Depending upon various conditions a MIL may occur due to DTC P0303 - Cylinder #3 Misfire.

This condition may be caused by heat from the exhaust manifold that following engine shut down migrates to the area around injector #3 and causes fuel vapor to form within the injector. This in turn may cause a momentary misfire of cylinder #3 until the fuel vapor is cleared of injector #3. The insulator sleeve lowers the injector #3 temperature to a point below which the fuel will not normally vaporize.

If vehicle exhibits a rough idle, and if a misfire of cylinder #3 is observed following a 10 to 20 minute hot soak, perform the Repair Procedure.

Parts required:
56028371AA Ignition Wire Shield

Repair procedure:
1. Cut insulator sleeve, p/n 56028371AA, to make two (2) insulator sleeves about 25-30 mm (1 in.) in length. See diagram.
2. Install one sleeve around injector #3, with the slit on the upward facing side of the injector. Install the other sleeve with the slit on the downward facing side of the injector.
3. Confirm sleeve is flush to intake manifold surface around injector.
4. Check injector #3 wire and ensure that the injector is rotated to a 2 o'clock position (from driver?s side of vehicle).
 
I hate it when that happens!!! Heat soak will cause the fuel in the fuel rail to boil and turn to vapor. Can't really run on that. Some people put heat shielding below the intake manifold to help shield all of that stuff from the exhaust manifold heat. Also check fuel pressure as low pressure allows fuel to vaporize more easily. Leaking injector can drop pressure and wet one cylinder making hard start/rough start too. This usually causes hard start cold as well though, as pressure has leaked out of rail and has to rebuild before starting. Hope this helps. Jim
 
lazyxj said:
This is a common problem with late model XJs, including my 2001.
My XJ does it a lot on hot days or when off-roading, especially after a long slow climb. It's so common that I carry a code reader for clearing the various misfire codes.
I have tried many things to cure including the solution below in the TSB below. I have had the best results by wiring in a switch and an adjustable time-delay relay that leaves the aux fan on for several minutes after the engine has been turned off.

I sometimes wonder if a fresh set of injectors would help prevent this problem. It was not a problem when the XJ had low miles.

A few weeks ago, I noticed that a friend's 2000 TJ had metal insulators under each injector, something XJs do not have. His 4.0 never has a hot soak problem.
I have not been successful finding the insulators online.


TSB
1803103 - 4.0L ROUGH ENGINE IDLE AFTER RESTART FOLLOWING A HOT SOAK
Date: 09/05/03 (supercedes 1802702 dated 09/06/02)
Model Year(s): 1999-2004

Description: NOTE: This bulletin applies to vehicles equipped with a 4.0L engine. This bulletin involves the installation of a fuel injector insulator sleeve.

Details: Customers may describe a 20 to 30 second rough idle following the restart of a heat soaked engine. This condition may be most noticeable when the engine is restarted following a prior 10 to 20 minute heat soak in hot ambient conditions of approximately 32 C (90ºF) or higher. This condition may be consistent with short city stop-and-go driving trips and can be aggravated by the use of fuel with a high ethanol content. Depending upon various conditions a MIL may occur due to DTC P0303 - Cylinder #3 Misfire.

This condition may be caused by heat from the exhaust manifold that following engine shut down migrates to the area around injector #3 and causes fuel vapor to form within the injector. This in turn may cause a momentary misfire of cylinder #3 until the fuel vapor is cleared of injector #3. The insulator sleeve lowers the injector #3 temperature to a point below which the fuel will not normally vaporize.

If vehicle exhibits a rough idle, and if a misfire of cylinder #3 is observed following a 10 to 20 minute hot soak, perform the Repair Procedure.

Parts required:
56028371AA Ignition Wire Shield

Repair procedure:
1. Cut insulator sleeve, p/n 56028371AA, to make two (2) insulator sleeves about 25-30 mm (1 in.) in length. See diagram.
2. Install one sleeve around injector #3, with the slit on the upward facing side of the injector. Install the other sleeve with the slit on the downward facing side of the injector.
3. Confirm sleeve is flush to intake manifold surface around injector.
4. Check injector #3 wire and ensure that the injector is rotated to a 2 o'clock position (from driver?s side of vehicle).
Click to expand...

Just what I was looking for. Thanks X EleventyBillion!!
 
Yep, as posted above, I override my aux fan whenever I shut the Jeep off on the trail to avoid the crappy startup. Works like a charm.
 
Man I love the NAXJA forums!! This is the second or third time I have had a problem with my 2000 XJ and searched my symptons to find others with exactly the same issue and the TSB that covers it. Thanks for posting this info it is indispensable. If only every popular car had a forum with a group of enthusiasts as intelligent, helpful and involved as the NAXJA group all crooked mechanics would be out of work and the dealership service departments would be able to charge us extra for ther time spent screwing around trying to find the solutions to erratic problems.

What is described above is exactly the issue I have experienced lately and I am so happy that now I can call the delaership with this exact TSB number and get an accurate qoute for install of the heat shield fix.

It is also interesting that they mention that fuel with high ethanol content can contribute to the problem and considering this TSB was realeased in 2003 doesn't that pretty much cover most all gas now that states 10% ethanol on the pump?

I like the fan time delay switch idea, seems like something that should be a standard built in the cherokees being that they have been known to run hot for years, but with a problem being erractic like this one I prefer not to have a dash switch for that sake that upon resale in the average consumer market a overheat or "heat soak" problem with a visable fan switch would look like a good reason not to buy a vehicle to many average consumers. I think the idea of having a timed delay relay that runs the fan automatically for 30 seconds upon shutoff is a better solution, but I am thinking the best solution and most trick setup would be to tap into the headlamp time delay shutoff, so in essence you have a controllable switch situation with a time delay built in, and considering this only happens on short stop and goes when the ambient temperature is high and engine compartment doesn't have a chance to cool off, i think this would be a great solution. If any of the in house NAXJA electrical gurus can help me set up a relay for the electric fan by tapping into the headlight time delay shutoff, it would be greatly appreciated. Thanks!!
 
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