4.0 engine missfire
03-16-2010, 07:39 PM
#1
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4.0 engine missfire
I have 2000 XJ 4.0. The engine will sometimes miss after start up when its been up to temp then shut down for 5-10 minutes. Like when you pull into convince store. It only does it about 25% of the time. If you rev the motor it will usually clear up and once you get back up to 1500 rmp your fine. You can drive at highway speed for hours no problem.
I had it to an off road park for the first time this weekend - it ran horrible. After about 40 min of low speed low range driving the motor started to miss. At first it would clear if you reved the motor a few times. It soon got so bad I had to shut it down (check engine light flashing). It wouldn't start until it cooled down about 1/2 hr- then started up and ran fine for about 1/2 hour then repeated same problem. Went through this cycle a couple times just to get back out of the off road park. Once I got it on the highway it ran fine 45 min trip home.
spark plugs and coil pack were already replace prior to off road park. code was reading cyl 3 misfire prior to going to park. After the trip to the park there were 6 misfire code readings -one for each cylinder. I've been running it 45min each way to work last two days - no problems.
Any suggestions
I had it to an off road park for the first time this weekend - it ran horrible. After about 40 min of low speed low range driving the motor started to miss. At first it would clear if you reved the motor a few times. It soon got so bad I had to shut it down (check engine light flashing). It wouldn't start until it cooled down about 1/2 hr- then started up and ran fine for about 1/2 hour then repeated same problem. Went through this cycle a couple times just to get back out of the off road park. Once I got it on the highway it ran fine 45 min trip home.
spark plugs and coil pack were already replace prior to off road park. code was reading cyl 3 misfire prior to going to park. After the trip to the park there were 6 misfire code readings -one for each cylinder. I've been running it 45min each way to work last two days - no problems.
Any suggestions
03-16-2010, 07:57 PM
#2
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Year: 1996
Model: Cherokee
Engine: 4.0 upgraded
check your gap, that was the problem with an 01 i worked on. everything was fine and random it would miss fire. fixed the gaps and it ran perfect. i run them .45
03-21-2010, 02:32 PM
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Year: 1996
Model: Cherokee
Engine: 4.0L HO
I am having the EXACT problem with mine, to the T. I haven't been able to figure it out either. I can drive all day long with no problems its just the sitting and slow driving while Im at my local off road park that its got its issues. Even on a hot day I can drive it around town and it doesn't do it. I got the same misfire codes with mine. My XJ is a 96 and my brothers is a 2000 and they both have this issue. I replaced all the ignition parts and cleaned the Air Idle Valve out and it still does it. I put clothes pins on my fuel rail to dissipate heat faster...some guy told me that trick fixed his, but I still have the same problem.
My guess to is the heat problem with the fuel system. I was going to try and put some spark plug insulators over the injectors to see if that helped. Maybe wrap the fuel rail in header wrap?
My guess to is the heat problem with the fuel system. I was going to try and put some spark plug insulators over the injectors to see if that helped. Maybe wrap the fuel rail in header wrap?
03-21-2010, 03:51 PM
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Year: 1996
Model: Cherokee
Engine: 4.0L HO
Yeah, but the only problem with wrapping the header is that stuff holds in moisture allowing the header to rust away faster. I live in Washington state so Its always wet, lol. I think if I had the cash I would get it ceramic coated inside and out. I was also thinking about building a heat shield between the header and manifold.
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03-21-2010, 04:34 PM
#8
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Year: 1995
Model: Cherokee
Engine: 4.0L High Output
Many times the cylinder #3 misfire can be caused by the fuel vaporizing inside the #3 injector due to heat soak from the intake manifold. Your right on line fivendime with fabricating some sort of heat shield between the intake and exhaust manifolds. You can also use a bit of the heat tape to wrap each injector to insulate them as well. Either approach seems to help. I was even thinking of using some heat shield material like this stuff... http://www.summitracing.com/parts/DEI-010462/ And just stick it all on the underside of my intake manifold, and up and around the sides of the runners as well since the exhaust manifold pipes pass very close there. Doing this as well as wrapping my injectors should get rid of that misfire.
03-21-2010, 06:15 PM
#9
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Year: 1994
Model: Cherokee
Engine: 98 4.0 swap
Check you valve adjustment in your head mine is screwy on cyl 5 it has a 90psi difference in compression with 0% leak down, or your distributor might be wearing out and the center rod might jiggle around inside and not fire correctly.
03-21-2010, 06:27 PM
#10
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Year: 2001
Model: Cherokee
Engine: inline 6
I have had this problem too. I just got some header wrap but I am also concerned about it holding moisture. I think I might order the tape that funkle95xj posted the link to.
03-21-2010, 09:27 PM
#11
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I put the insulator on injector 3 from the tsb. It seemed to help a little with the hot start up but the slow driving problem did not go away. I think I will try the reflective tape and header wrap both. If I cant get it to run better off road soon I'll probably take it to a garage and hope they can figure something out.
03-21-2010, 11:38 PM
#12
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Year: 2001
Model: Cherokee
Engine: 4.0
Do your guys check engine light ever go away without a "fix"? Mine hasnt since it came on 2 days ago for cylinder 3 misfire.
03-23-2010, 07:40 PM
#13
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Year: 1996
Model: Cherokee
Engine: 4.0L HO
Yeah, I have had it come on a few times with the #3 misfire code, but it goes off on its own. Unplug the positive side of the battery for like 5 min and then it should turn off. That also makes the computer reset the parameters for the elevation. Where I go wheeling is way higher in elevation and when I unplug the battery, wait, then plug it back in it always runs better. But I hate doing that or making people wait for my XJ on the trails.
03-23-2010, 07:51 PM
#14
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Link http://www.wjjeeps.com/tsb/tsb_wj_1803103.pdf
This bulletin is supplied as technical information only and is not an authorization for repair.
THIS BULLETIN SUPERSEDES TECHNICAL SERVICE BULLETIN 18-027-02,
DATED SEPTEMBER 06, 2002, WHICH SHOULD BE REMOVED FROM
YOUR FILES. THIS IS A COMPLETE REVISION AND NO ASTERISKS
HAVE BEEN USED TO HIGHLIGHT REVISIONS.
SUBJECT:
4.0L Rough Engine Idle After Restart Following A Hot Soak
OVERVIEW:
This bulletin involves the installation of a fuel injector insulator sleeve.
MODELS:
2000-2004 (TJ) Wrangler (Domestic and International Markets)
1999-2004 (WJ) Grand Cherokee (Domestic and International Markets)
2001-2004 (WG) Grand Cherokee (International Market)
2000-2001 (XJ) Jeep Cherokee (Domestic and International Markets)
NOTE: This bulletin applies to vehicles equipped with a 4.0L engine (sales code = ERH)
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 (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.
DIAGNOSIS:
1. 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:
Qty. Part No. Description
1 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.
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).
POLICY:
Reimbursable within the provisions of the warranty.
TIME ALLOWANCE: 0.2hrs
FAILURE CODE:
AM Authorized Modification
THIS BULLETIN SUPERSEDES TECHNICAL SERVICE BULLETIN 18-027-02,
DATED SEPTEMBER 06, 2002, WHICH SHOULD BE REMOVED FROM
YOUR FILES. THIS IS A COMPLETE REVISION AND NO ASTERISKS
HAVE BEEN USED TO HIGHLIGHT REVISIONS.
SUBJECT:
4.0L Rough Engine Idle After Restart Following A Hot Soak
OVERVIEW:
This bulletin involves the installation of a fuel injector insulator sleeve.
MODELS:
2000-2004 (TJ) Wrangler (Domestic and International Markets)
1999-2004 (WJ) Grand Cherokee (Domestic and International Markets)
2001-2004 (WG) Grand Cherokee (International Market)
2000-2001 (XJ) Jeep Cherokee (Domestic and International Markets)
NOTE: This bulletin applies to vehicles equipped with a 4.0L engine (sales code = ERH)
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 (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.
DIAGNOSIS:
1. 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:
Qty. Part No. Description
1 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.
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).
POLICY:
Reimbursable within the provisions of the warranty.
TIME ALLOWANCE: 0.2hrs
FAILURE CODE:
AM Authorized Modification
03-23-2010, 08:29 PM
#15
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This problem is showing up more often now (will continue to do so) that that the gas companies are selling E10,E15,Ive heard of E20 fuels as stated in the TSB. Ethanol also draws in moisture pretty bad leading to drivablity issues.Just my .02