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XJ misses out after it warms up on restart

xjaholic

NAXJA Forum User
Location
Round Rock, TX
What is causing my 2001 XJ to miss when I restart it? If I drive and park, then run back 5 minutes later and the temperature is at about 215, it sounds like a boat in the water.
 
Does it continue to miss, or does it smooth out later? Also, does it set off any check engine codes?

An engine will heat up a bit after you shut it down, and electrical devices that are on the brink of failure might misbehave as a result. If this is a distributorless engine, I would look at one of the spark coils. My stepson's 93 also had a problem that appeared when it got hot (usually after being parked, but also occasionally while running) which turned out to be a bad splice in the wiring harness, which increased its resistance just enough to kill one of the injectors. This problem sent a trouble code - an unhelpful one, but something.

I think your first job will be to see if you can narrow it down to fuel or spark. A vacuum gauge would be very helpful there.
 
It misses out until the temp goes back down to about 200. If you give it any gas, the check engine light comes on. It only happens when the temperature goes to the 215 level after I shut it off.
 
Mine did the same thing. Chrysler released a service bulletin about the number 3 injector experiencing vapor lock, need to wrap a heat shield around the injector. When I had the same problem a few months back I did a search on "rough idle", I think, and someone posted the exact service bulletin Chrysler released, part no. for heat shield and all. Also stated increased amounts of ethanol in the gas makes the problem worse and there's lots, 10%, mixed in the gas in the midwest. Hope this helps. The heat shield around the injector worked for me.
 
Fuel System - Hot Start Misfire/MIL ON/DTC's/Rough Idle
NUMBER: 18-031-03

SYMPTOM/CONDITION:

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 (90°F) 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.

REPAIR PROCEDURE:
1. Cut insulator sleeve, p/n 56028371AA, to make two (2) insulator sleeves about 25-30 mm (1 in.) in length.

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).
 
Thanks alot guys! I'll try this after getting my lift on this weekend. It will only get worse since I drive my Jeep all day long, and the summers here are quite warm to say the least.
 
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