vague question...
Junior Member
Joined: Oct 2011
Posts: 76
Likes: 0
From: Richmond, Va
Year: 2001
Model: Cherokee
Engine: 4.0
I'm definitely having this problem. Code po303. Glad I found this. Only happens if restart within in 20 minutes.
I'm also getting a po455 evap leak large. I have replaced almost all fittings on intake, filter box back by rear axle, and replaced gas cap. It still came up with The 303 code.
Can these problems relate?
If my 455 hadn't fixed this time I was gonna pay for a smoke test. Now I'm wondering if I should fix this first and wait or fix it and plan on smoke test.
I'm also getting a po455 evap leak large. I have replaced almost all fittings on intake, filter box back by rear axle, and replaced gas cap. It still came up with The 303 code.
Can these problems relate?
If my 455 hadn't fixed this time I was gonna pay for a smoke test. Now I'm wondering if I should fix this first and wait or fix it and plan on smoke test.
Senior Member
Joined: Jan 2011
Posts: 689
Likes: 2
From: Upstate N.Y
Year: 2000.1999,1996
Model: Cherokee
Engine: 4.0
I'm definitely having this problem. Code po303. Glad I found this. Only happens if restart within in 20 minutes.
I'm also getting a po455 evap leak large. I have replaced almost all fittings on intake, filter box back by rear axle, and replaced gas cap. It still came up with The 303 code.
Can these problems relate?
If my 455 hadn't fixed this time I was gonna pay for a smoke test. Now I'm wondering if I should fix this first and wait or fix it and plan on smoke test.
I'm also getting a po455 evap leak large. I have replaced almost all fittings on intake, filter box back by rear axle, and replaced gas cap. It still came up with The 303 code.
Can these problems relate?
If my 455 hadn't fixed this time I was gonna pay for a smoke test. Now I'm wondering if I should fix this first and wait or fix it and plan on smoke test.
Member
Joined: May 2009
Posts: 172
Likes: 2
From: CT
Year: 2001
Model: Cherokee
Electric's XJ - I don't think they relate to each other....The large evap leak should be easier to find than the small one....Did you check the vacuum ball for cracks?...No disconnected hoses?...I read somewhere here about the filler neck to the gas tank coming loose or cracking too..might check that...
XJtlk789 - Maybe try switching the injectors around and see if the misfire follows....I had misfire and long cranking problems with my Jeep...I upgraded the injectors and all my starting and misfire problems went away...Not saying to replace yours but maybe test/clean them to eliminate them from being part of the problem..
XJtlk789 - Maybe try switching the injectors around and see if the misfire follows....I had misfire and long cranking problems with my Jeep...I upgraded the injectors and all my starting and misfire problems went away...Not saying to replace yours but maybe test/clean them to eliminate them from being part of the problem..
Junior Member
Joined: Nov 2010
Posts: 51
Likes: 0
From: GC, Michigan
Year: 98
Model: Cherokee
Engine: 4.0
How's the idle after a hot restart?.....Could be a heat soak problem....00's and 01's seem to be more apt to have this issue....
This is the TSB from Jeep.
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 is the TSB from Jeep.
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.
CF Veteran
Joined: Nov 2010
Posts: 5,840
Likes: 117
From: In the middle of Minnesota!
Year: 1999
Model: Cherokee
Engine: 4.0
It's a sleeve for around the fuel injector. Take the above part number to a Jeep dealer to purchase. If they don't have it, they can order it. Or you can just make this yourself as it is very basic.
But I've found that this fix is kind of "hit and miss", and works only on mild cases of heat soak. More stubborn cases need fixes like an e-fan timer that leaves the e-fan on for a longer period after the key is turned off to reduce engine bay temps. Or louvers. Or both.
But I've found that this fix is kind of "hit and miss", and works only on mild cases of heat soak. More stubborn cases need fixes like an e-fan timer that leaves the e-fan on for a longer period after the key is turned off to reduce engine bay temps. Or louvers. Or both.
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