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12-07-2011, 07:06 PM
#2
CF Veteran
TSB concerning Cylinder 3 Misfire:
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.
18-031-03 -2-
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).
Also:
SUBJECT:
4.0L Multiple Cylinder Misfire
OVERVIEW:
This bulletin involves inspection of all engine exhaust valves and a decarbonizing
procedure if necessary.
MODELS:
1999 - 2004 (WJ) Grand Cherokee (All Markets)
2001 - 2004 (WG) Grand Cherokee (International Markets)
1999 - 2004 (TJ) Wrangler
1999 - 2001 (XJ) Cherokee
NOTE: THIS BULLETIN APPLIES TO VEHICLES EQUIPPED WITH A
4.0L ENGINE (SALES CODE = ERH).
SYMPTOM/CONDITION:
The customer may experience an incident of engine misfire during certain vehicle
operating conditons. The misfire may occur when the vehicle is operated between
80 - 112 KPH (50 - 70 MPH) and under light loading conditions, e.g. slight uphill
road grades. This condition may occur at all ambient conditions, but is more
noticeable when ambient conditons are less than 0 C (32 F).
If the vehicle is equipped with On-Board Diagnostic (OBD), a MIL illumination may also
have occurred due to Diagnostic Trouble Code (DTC) P0300 - Mulitiple Cylinder Misfire.
Various single cylinder misfire DTC's may also be present. If the frequency of misfire is
high the Powertrain Control Module (PCM) may place the engine in "Limp-In" mode.
The misfire condition may be caused by one or more engine exhaust valves that are
slow to close. Late closure of an exhaust valve may be the result of no valve rotation
and associated build up of carbon on the exhaust valve stem.
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.
18-031-03 -2-
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).
Also:
SUBJECT:
4.0L Multiple Cylinder Misfire
OVERVIEW:
This bulletin involves inspection of all engine exhaust valves and a decarbonizing
procedure if necessary.
MODELS:
1999 - 2004 (WJ) Grand Cherokee (All Markets)
2001 - 2004 (WG) Grand Cherokee (International Markets)
1999 - 2004 (TJ) Wrangler
1999 - 2001 (XJ) Cherokee
NOTE: THIS BULLETIN APPLIES TO VEHICLES EQUIPPED WITH A
4.0L ENGINE (SALES CODE = ERH).
SYMPTOM/CONDITION:
The customer may experience an incident of engine misfire during certain vehicle
operating conditons. The misfire may occur when the vehicle is operated between
80 - 112 KPH (50 - 70 MPH) and under light loading conditions, e.g. slight uphill
road grades. This condition may occur at all ambient conditions, but is more
noticeable when ambient conditons are less than 0 C (32 F).
If the vehicle is equipped with On-Board Diagnostic (OBD), a MIL illumination may also
have occurred due to Diagnostic Trouble Code (DTC) P0300 - Mulitiple Cylinder Misfire.
Various single cylinder misfire DTC's may also be present. If the frequency of misfire is
high the Powertrain Control Module (PCM) may place the engine in "Limp-In" mode.
The misfire condition may be caused by one or more engine exhaust valves that are
slow to close. Late closure of an exhaust valve may be the result of no valve rotation
and associated build up of carbon on the exhaust valve stem.
12-08-2011, 05:16 AM
#4
CF Veteran
Join Date: Nov 2010
Location: In the middle of Minnesota!
Posts: 5,805
Received 99 Likes
on
88 Posts
Year: 1999
Model: Cherokee
Engine: 4.0
The 00-01 engines are by far the most susceptible to "heat soak", which usually manifests itself in a cylinder 3 misfire.
Beware though that the above fuel injector sleeve retrofit fix may work on "mild" cases, but hasn't worked for many. For stubborn cases, what has worked is an e-fan timer that is programmed to allow the e-fan to continue to run for a predetermined amount of time when the key is turned off so as to lower engine bay temperatures. Others have cut louvers into the engine to get engine bay temps down. Some have done BOTH. Search this forum and others (NAXJA) for lots of information and the "how to" on these fixes. It is not at all uncommon.
And I'll bring this up even though it may not apply (hopefully). The 00-01 has the 0331 cylinder head from the factory, which is susceptible to cracking between cylinders 3-4 because of a casting defect.
If you have a cylinder 3 misfire AND you are having to add antifreeze to your coolant reservoir, suspect a cracked head. The #1 symptom of a cracked 0331 cylinder head is "unexplained coolant loss". I may sound like a broken record with this statement, but if it can help one owner discover their cracked head early enough to save their engine, then it's been worth it.
Good luck!
Beware though that the above fuel injector sleeve retrofit fix may work on "mild" cases, but hasn't worked for many. For stubborn cases, what has worked is an e-fan timer that is programmed to allow the e-fan to continue to run for a predetermined amount of time when the key is turned off so as to lower engine bay temperatures. Others have cut louvers into the engine to get engine bay temps down. Some have done BOTH. Search this forum and others (NAXJA) for lots of information and the "how to" on these fixes. It is not at all uncommon.
And I'll bring this up even though it may not apply (hopefully). The 00-01 has the 0331 cylinder head from the factory, which is susceptible to cracking between cylinders 3-4 because of a casting defect.
If you have a cylinder 3 misfire AND you are having to add antifreeze to your coolant reservoir, suspect a cracked head. The #1 symptom of a cracked 0331 cylinder head is "unexplained coolant loss". I may sound like a broken record with this statement, but if it can help one owner discover their cracked head early enough to save their engine, then it's been worth it.
Good luck!
