about to take a hammer to 2001 cherokee sport
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Joined: Jul 2009
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Model: Cherokee
about to take a hammer to 2001 cherokee sport
ok, before this goes a dozen different directions, i have worked on my own rigs for 25+ years, i restore old mopars, and have3, and have owned and built atleast 10 XJ's previously. this 2001 cherokee sport has me stumped. and yes, have searched,and searched,and searched on here, and keep finding alot of the same problem, and all the answers running in circles, in other words,......no answer. so, that said.......
2001 cherokee sport, 127,XXX miles,4.0,blah,blah. anywho, check engine light on and flashing at times. code PO300 i think, multiple cylinder missfires, then, cylinder 1 missfire confirmed, cylinder 2 missfire confimed, cylinder 3 missfire confirmed. rough idle, above idle, runs great. changed plugs, gapped them correctly(correct champions, and autolite platinums) no change.
replaced coil rail with new rail from 3 different parts stores. not only does the truck run far worse with the new rails, it will not pull or rev above 2500 rpm.
put another used rail off another 2001 XJ ,a good running,albeit wrecked on in a buddies junk yard,....no chnage,same codes,revs to the stars,etc.
left battery unhooked for 72 hours, hooked it back up, no change, same codes came back up.
installed new TPS, from 2 parts stores, and a new mopar part from our local dealer, same codes, no change, but, again, will not rev above 2500 rpm. installed used one from other running 2001, no change, same codes, revs to the stars,etc.
tested coolant system, no blockage, no leaks, no head gasket issues,all cyl. strong compression.injectors all checked out, working properly,etc,etc,etc.
only thing haven't checked out is the converter, doing that in the morning.
doesn't hard start after heat soak either.
this thing is driving me nuts, any help would be appreciated. thanks in advance......
2001 cherokee sport, 127,XXX miles,4.0,blah,blah. anywho, check engine light on and flashing at times. code PO300 i think, multiple cylinder missfires, then, cylinder 1 missfire confirmed, cylinder 2 missfire confimed, cylinder 3 missfire confirmed. rough idle, above idle, runs great. changed plugs, gapped them correctly(correct champions, and autolite platinums) no change.
replaced coil rail with new rail from 3 different parts stores. not only does the truck run far worse with the new rails, it will not pull or rev above 2500 rpm.
put another used rail off another 2001 XJ ,a good running,albeit wrecked on in a buddies junk yard,....no chnage,same codes,revs to the stars,etc.
left battery unhooked for 72 hours, hooked it back up, no change, same codes came back up.
installed new TPS, from 2 parts stores, and a new mopar part from our local dealer, same codes, no change, but, again, will not rev above 2500 rpm. installed used one from other running 2001, no change, same codes, revs to the stars,etc.
tested coolant system, no blockage, no leaks, no head gasket issues,all cyl. strong compression.injectors all checked out, working properly,etc,etc,etc.
only thing haven't checked out is the converter, doing that in the morning.
doesn't hard start after heat soak either.
this thing is driving me nuts, any help would be appreciated. thanks in advance......
::CF Moderator::
Joined: Aug 2011
Posts: 43,971
Likes: 1,578
From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
Following the codes would be the most logical way to go.
Here's how to check for clogged exhaust using a $15 gauge.
CRUISER’S VACUUM TEST FOR EXHAUST RESTRICTION
Your vacuum gauge should come with an instruction booklet outlining the procedure. Hook the vacuum gauge up to a source on the intake manifold. Start the engine and note the vacuum reading. Usually 17 to 21 inches of vacuum. Throttle the engine up to 2,000 to 2,500 RPM for 20 seconds or so and the vacuum reading should stabilize to the same reading you got at idle. Let the throttle snap shut. The vacuum reading should shoot up about 5 inches of vacuum higher for a second and then come quickly down to the original reading. If the vacuum reading stays high and comes down slowly with jerky needle movements, you have an exhaust restriction.
Senior Member
Joined: Feb 2012
Posts: 905
Likes: 8
From: New Hampshire
Year: 1998
Model: Cherokee
Engine: 4.0L I6
Kinda shotgunning here, aren't we?
Following the codes would be the most logical way to go.
Here's how to check for clogged exhaust using a $15 gauge.
CRUISER’S VACUUM TEST FOR EXHAUST RESTRICTION
Your vacuum gauge should come with an instruction booklet outlining the procedure. Hook the vacuum gauge up to a source on the intake manifold. Start the engine and note the vacuum reading. Usually 17 to 21 inches of vacuum. Throttle the engine up to 2,000 to 2,500 RPM for 20 seconds or so and the vacuum reading should stabilize to the same reading you got at idle. Let the throttle snap shut. The vacuum reading should shoot up about 5 inches of vacuum higher for a second and then come quickly down to the original reading. If the vacuum reading stays high and comes down slowly with jerky needle movements, you have an exhaust restriction.
Following the codes would be the most logical way to go.
Here's how to check for clogged exhaust using a $15 gauge.
CRUISER’S VACUUM TEST FOR EXHAUST RESTRICTION
Your vacuum gauge should come with an instruction booklet outlining the procedure. Hook the vacuum gauge up to a source on the intake manifold. Start the engine and note the vacuum reading. Usually 17 to 21 inches of vacuum. Throttle the engine up to 2,000 to 2,500 RPM for 20 seconds or so and the vacuum reading should stabilize to the same reading you got at idle. Let the throttle snap shut. The vacuum reading should shoot up about 5 inches of vacuum higher for a second and then come quickly down to the original reading. If the vacuum reading stays high and comes down slowly with jerky needle movements, you have an exhaust restriction.
I know it's a random question.
CF Veteran
Joined: Jan 2009
Posts: 1,964
Likes: 6
From: Baltimore, Maryland
Year: 1994 1993
Model: Cherokee
Engine: 4.0
I believe 2001 XJs are famous for having a bad "heat soak" issue with the injectors especially those near the center. This causes all sorts of problems including the misfire codes and issues. Do a Google search for 2001 XJ and heat soak and you'll find all sorts of info.
::CF Moderator::
Joined: Aug 2011
Posts: 43,971
Likes: 1,578
From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
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Thread Starter
Newbie
Joined: Jul 2009
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Model: Cherokee
yep, going to do away with,.....um,...i mean, check out the converter tomorrow.......
as far as the codes go, PO300, PO301,PO302, PO303 as stated in the first post, multiple cyl missfires, missfires on cyl 1,2,3. i have been following the codes, has led me nowhere.......i appreciate all the input. got to be a solution somewhere.
as far as the codes go, PO300, PO301,PO302, PO303 as stated in the first post, multiple cyl missfires, missfires on cyl 1,2,3. i have been following the codes, has led me nowhere.......i appreciate all the input. got to be a solution somewhere.
Last edited by superbyrd; Feb 27, 2013 at 10:27 PM.
CF Veteran
Joined: Apr 2012
Posts: 5,302
Likes: 23
From: Wisconsin
Model: Cherokee
Here is the TSB regarding injector heat soak:
There is another TSB for multiple cylinder misfires covering valve spring issues, which is sounding fairly likely given what you've posted:
http://www.wjjeeps.com/tsb/tsb_wj_0900303.pdf
.
NUMBER: 18-031-03
GROUP: Vehicle Performance
DATE: Sep. 05, 2003
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 ********S 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 (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.
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
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.
GROUP: Vehicle Performance
DATE: Sep. 05, 2003
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 ********S 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 (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.
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
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.
There is another TSB for multiple cylinder misfires covering valve spring issues, which is sounding fairly likely given what you've posted:
http://www.wjjeeps.com/tsb/tsb_wj_0900303.pdf
.
Last edited by Radi; Feb 28, 2013 at 02:32 AM.
CF Veteran
Joined: Apr 2012
Posts: 5,302
Likes: 23
From: Wisconsin
Model: Cherokee
I've seen youtube videos of people doing that, the laundry soap thing. They say it works, but then again it's youtube. I've never seen or heard anyone reputable suggest doing it.
Personally I'd think it would present the same problems as flushing an old, worn transmission, working just enough crap loose to turn obstructions into complete blockages.
CF Veteran
Joined: Jun 2010
Posts: 2,501
Likes: 4
From: Flint/Asheville
Year: 1995
Model: Cherokee
Engine: 4.0 HO
I helped a family friend with a 2000 grand cherokee he got for cheap, i was skeptical from the get go with the misfire and rough idle. Found an injector that looked like it almost blew up and changed it, he changed the coil pack, spark plugs and the basic stuff but still had the misfire. I went back and did a compression check and leak down test with cylinder 3 or 4 weak: cracked head but with no water in the oil and wasnt running hot. New head and it ran great. Try those two next
CF Veteran
Joined: Sep 2009
Posts: 8,567
Likes: 20
From: ☼ Blackhole Sun
Year: My Jeep is a GMC
I helped a family friend with a 2000 grand cherokee he got for cheap, i was skeptical from the get go with the misfire and rough idle. Found an injector that looked like it almost blew up and changed it, he changed the coil pack, spark plugs and the basic stuff but still had the misfire. I went back and did a compression check and leak down test with cylinder 3 or 4 weak: cracked head but with no water in the oil and wasnt running hot. New head and it ran great. Try those two next
CF Veteran
Joined: Jun 2010
Posts: 2,501
Likes: 4
From: Flint/Asheville
Year: 1995
Model: Cherokee
Engine: 4.0 HO
Nope, once i saw the weaker compression and fast leak down i tore the head off, he took it to our local engine builder and the report was junk head. I just assumed junk head from day 1 and was right.