hello i have 2001 cherokee and im having a misfire in the 3rd cylinder and ive changed the coil pack and it came with new boots also put in brand autolite platniums with .35 gap and still having a misfire.... i was thinking it could be the 3rd injector but i dont know whats the order the cylinders are in or could it be some thing else i also thought what i think the part is called the igniator coil which sits by the oil filter set up and oil presure sending unit i heard a wierd sound coming for it the car start but in a few tries defitinely idles rough and some it will stall out when driving or idling thank u for the help

 

Check the throttle position sensor

 

You could be experiencing "heat soak". It affects cylinder #3 first. There is a technical service bulletin about this. There is also a TSB on rough idle for 00-01. Here you go.....
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TSB 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 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.

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 intake manifold surface around injector.
4. Check injector #3 wire and ensure that the injector is rotated to a 2 o'clock position.

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2000-2001 Rough Idle TECHNICAL SERVICE BULLETINS

2000-2001
ROUGH IDLE / MULTIPLE CYLINDER MISFIRE
1801301 - ROUGH IDLE AT COLD TEMPERATURES
Date: 06/11/01
Model Year(s): 2000

Description: Some vehicles may exhibit a rough idle and / or Malfunction Indicator Lamp (MIL) light on condition upon initial start-up after a cold soak when temperatures are below 50 degrees F (10 degrees c). This bulletin involves selectively erasing and reprogramming the Control Module (PCM) with new software (Cal level 00Cal15C).

1801001 - ROUGH IDLE AT COLD TEMPERATURES
Date: 04/20/01
Model year(s): 2001

Description: THIS BULLETIN APPLIES TO VEHICLES BUILT PRIOR TO APRIL 30, 2001 AND CALIBRATION LEVEL PRIOR TO (LESS OR LOWER THAN) THOSE LISTED IN THE OVERVIEW ABOVE. This bulletin involves selectively erasing and reprogramming the Powertrain Control Module (PCM) with new software (WJ/TJ ? calibration level 01Cal14C, XJ ? calibration level 15B.)

 

my car is throwing a check engine im gonna do the insulator for the injector but how would i reclibrate the pcm... i also was wondering if anybody has a pic of what that insulator would look like after i do the cutting and install it

 

How do u recalibrate the PCM or whatever I would have to do to take care of the cold soak

 

Any help