I have a 4.0. After the engine is warmed up and it's shut off for longer that 10 min, when starting, the engine runs rough like it is missing and might stall. This is worse when you are in gear with the brake applied. After you drive for a few minutes the idle returns to normal. Driving under a load is normal. This will happen again if you allow the engine to sit off for at least 15 min. Got any ideas? The dealer is puzzled. Nothing shows on the computer yet. Thanks Ed firstname.lastname@example.org
I have the same problem, replaced all plug wires, rotor, cap, plugs, and injectors. i've cleaned all of the throttle body IAC and everything and it still feels like it's missing alittle. If anyone can figure it out you'd definately be on the awesome list.
Ok, So Whats The Speed Of Dark?
Injector #3 gets so hot in certain conditions that it vaporizes its fuel upon shutdown. I think this is what your problem is. It usually clears within 30 seconds of hot startup. If it happens very often or annoys you, you can wrap insulation around injector 3 and it will block the heat, thus solving the problem.
Edit: found the TSB, It applies to older vehicles too, I just found a different version.
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.
4.0L Rough Engine Idle After Restart Following A Hot Soak
This bulletin involves the installation of a fuel injector insulator sleeve.
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)
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.
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.
Qty. Part No. Description
1 56028371AA Ignition Wire Shield
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
Thanks. My buddy said he had the computer read and it said #3 cylinder misfire. This must be the problem. I forwarded the info. Thanks. Do you know if this is a recall item with a free repair? Thanks again!!!
Also heat shield between the exhaust and intake manifold works. I did this repair and the results were marginal as the heat sleeves tend to fall off over time and with fans blowing on them so I went with an actual heat shield instead works great, diverts the heat from under the intake and in turn from in to the injectors.
PS it's not just cylinder #3 that this will happen to I've had it happen to varies cylinders as always only on startup.