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Heat Soak

BigMike80

NAXJA Forum User
Location
San Diego
So I did this fix but Im wondering what it means to have the injector rotated to the 2o'clock position? Is that when Im looking at it from the drivers side of the vehicle?

If so what position should the other injectors be?

0900303 - 4.0L MULTIPLE CYLINDER MISFIRE
Date: 08/01/03
Model Year(s): 1999-2004

Description: NOTE: THIS BULLETIN APPLIES TO VEHICLES EQUIPPED WITH A 4.0L ENGINE. This bulletin involves inspection of all engine exhaust valves and a decarbonizing procedure if necessary.

Details: The customer may experience an incident of engine misfire during certain vehicle operating conditions. The misfire may occur when the vehicle is operated between 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 conditions 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 [COLOR=blue ! important][COLOR=blue ! important]Trouble [COLOR=blue ! important]Code[/COLOR][/COLOR][/COLOR] (DTC) P0300 - Multiple 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.

This condition may occur when the engine is not allowed to run at engine RPM?s that are greater than 3,200 RPM. At 3,200 RPM or higher the engine exhaust valves will rotate if not impeded by high carbon deposits. Low engine RPM?s and high carbon deposits are associated with short trip driving where the vehicle engine is not allowed to fully warm to normal engine operating temperatures. Cold ambient temperatures will increase engine warm-up time and add to the opportunity of carbon deposit build-up on the stem of the engine exhaust valve.




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 [COLOR=blue ! important][COLOR=blue ! important]exhaust [COLOR=blue ! important]manifold[/COLOR][/COLOR][/COLOR] 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 [COLOR=blue ! important][COLOR=blue ! important]intake [COLOR=blue ! important]manifold[/COLOR][/COLOR][/COLOR]
surface around injector.
4. Check injector #3 wire and ensure that the injector is rotated to a 2 o'clock position
 
Looking straight down the injector from the drivers side fender, they should be at 2 o'clock. Horizontal would be 3 o'clock. Straight up would be 12. Don't know why it matters. Easier to plug in?
 
BS fix.

It gets too hot in the engine bay, and Chryco fix is to wrap the injector. Road apples!

If you want to confirm if you have heat soak--drive your vehicle until it is good and hot. Park, shut off the engine, and open the hood for about 30 minutes. Restart the engine. If the symptoms are gone, you have heat soak. The only fix is to reduce the under-hood temperature.

Most other manufacturers that encountered this problem simply added a timer circuit in the efan to allow it to run when the engine is off for a short time to reduce the under-hood temperature. Chryco--a cheap piece of insulation.

The heat soak issue for the 1999-01 XJ is due to a number of issues. Redesign of the fuel system eliminating the return line from the fuel rail was a start, followed by the redesign of the manifolds, and compounded on some XJs with the addition of the 50-state emissions package--two pre-cats in the exhaust manifold right under the injectors.

another change Chryco had was to change from Champion plugs to NGK plugs in the effected model years.

I would recommend you come up with a way to reduce your under-hood temperatures. You can install an after-market timer to the efan circuit. Here is a link: http://www.at-fairfax.com/P1786-ELK-960.htm

Good luck.
 
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