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Unread 07-21-2013, 01:32 PM   #1
HooahYJ
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2001 TJ Wrangler 
 
Join Date: Oct 2010
Location: Fort Irwin, CA
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TJ Rough Idle

Im sure there is a thread already started but im not sure how to explain it. Today I was out driving in my jeep. I stopped for a minute onceI got back in the jeep and started it up and it had a real rough idle. I had to step on the gas to get it to half way run. My oil pressure gauge was low and it back fired when I pressed on the gas. Once I got the oil pressure back up to normal it seemed to do just fine on the way back home. What would cause low oil pressure and a rough idle. Only codes that are showing is P0455 (Evap Leak)

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Unread 07-21-2013, 05:20 PM   #2
Tblack
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Quote:
Originally Posted by HooahYJ View Post
Im sure there is a thread already started but im not sure how to explain it. Today I was out driving in my jeep. I stopped for a minute onceI got back in the jeep and started it up and it had a real rough idle. I had to step on the gas to get it to half way run. My oil pressure gauge was low and it back fired when I pressed on the gas. Once I got the oil pressure back up to normal it seemed to do just fine on the way back home. What would cause low oil pressure and a rough idle. Only codes that are showing is P0455 (Evap Leak)
This is a shot in the dark. Mine is only doing this in the summer and when it is offroad. When the engine gets really hot like that and then you shut it off, your engine does what is called a hot soak. Which means for a short time after shutting off the engine and the coolant is not moving through the engine like it does when it is running, the engine will actually get hotter. They had a problem with some of the 4.0's where the gasoline in the fuel rail and injectors would get really hot and cause a slight vapor lock condition. This situation would cause a similar problem.
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Unread 07-21-2013, 05:49 PM   #3
Knuckelhead
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Quote:
Originally Posted by HooahYJ View Post
Im sure there is a thread already started but im not sure how to explain it. Today I was out driving in my jeep. I stopped for a minute onceI got back in the jeep and started it up and it had a real rough idle. I had to step on the gas to get it to half way run. My oil pressure gauge was low and it back fired when I pressed on the gas. Once I got the oil pressure back up to normal it seemed to do just fine on the way back home. What would cause low oil pressure and a rough idle. Only codes that are showing is P0455 (Evap Leak)
Have you read this TSB:
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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.
-------------------------------------------------------------------------------------
This worked for my 2000 Sport...
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Unread 07-21-2013, 07:32 PM   #4
eagle223
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I had this problem on my XJ as well, I went with hood vents. Fixed my problem until the XJ got totaled.
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Unread 07-22-2013, 10:25 AM   #5
HooahYJ
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Thanks guys for the replies... I've never heard of TSB and it sounds like that might have been it. I was riding it pretty rough as if I was offroading. Thanks again for the info
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