4.0 engine Q

[cityslicker]

every once in a while my engine will missfire. its always after being a little heavy on the skinny peddal and it happens on startup and will run really rough for a while then it goes away..

What could be the cause of this? I have the 2000 xj so all the timing and stuff is controlled by the computer.

Now she's sluggish too. the peddle feels stiff and she really don't want to be moving it seems.

I'm wondering if these issues are related to some underlying problem I can fix. but I need some direction.. Gibbs.. thoughtS??

[Super Scout]

Possibly something in the ignition heating up while the jeep is off and not working right until it cools down some?

[limegreentj]

i read about this one time, it has something to do with the atomization of the fuel in the rail after shutoff, because its so close to the engine, the fuel heats up after shutoff, and causes it to run funny on startup. mine does it too, and its a 97 with a 4.0

[cityslicker]

http://www.youtube.com/watch?v=_RjMSWhGWak

and this is funny/

[PAFirefighter49]

Brandon's post makes sense....my first guess was with the injectors. Although I run a 99 TJ 4.0 and have never had an issue.

[JeepSteeler]

Since it is running sluggish, I'd go ahead and start inspecting your ignition system while you are at it. Take a look at the plugs and see if any of them are fouled or look different than the rest. Check your plug wires for cracks - when was your last cap/rotor tuneup?

I have headers on my 4.0 and even wrapped there is some serious heat in the engine bay from them, but I don't have this issue, not sure if it is fuel atomization.....

[cityslicker]

Since it is running sluggish, I'd go ahead and start inspecting your ignition system while you are at it. Take a look at the plugs and see if any of them are fouled or look different than the rest. Check your plug wires for cracks - when was your last cap/rotor tuneup?

I have headers on my 4.0 and even wrapped there is some serious heat in the engine bay from them, but I don't have this issue, not sure if it is fuel atomization.....

see thats the thing, there is no distributor, it's all computer... I'll check the plugs though.

[skeebs]

Throwing any codes? I am still going through similar crap on the wifes '01. Dealt with two TSB's on it over the past few weeks and it still isn't 100% right. My main issue seems to be with this bulletin:

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 (from driver’s side of vehicle).

[skeebs]

Just dealt with this PCM reprogram last week, so in due time I will see if this helps.




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

Description: THIS BULLETIN APPLIES TO VEHICLES EQUIPPED WITH A 4.0L (ERH) ENGINE 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.)

Details: Some vehicle engines may exhibit a rough idle and/or MIL light “on” condition upon initial start-up after a cold soak when temperatures are below 50°F (10°C).

[cityslicker]

Throwing any codes? I am still going through similar crap on the wifes '01. Dealt with two TSB's on it over the past few weeks and it still isn't 100% right. My main issue seems to be with this bulletin:

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 (from driver’s side of vehicle).

can u send me a liink to where you go that bulitin?

[skeebs]

can u send me a liink to where you go that bulitin?

I dug it up on Jeepforum.com.

See if this helps get you anywhere:

http://www.alldatadiy.com/recalls/index.html

[cityslicker]

nope they want money. ****ers.....

[skeebs]

This link may help too. Google the crap out of "Technical Service Bulletin(s)" for your Cherokee, I guarantee you'll find a lot of info out there for free

http://www.allworldauto.com/tsbs/200...25-2000-1.html

.............Or call a dealership and see if they are willing to print out a list of all the TSB's on the engine & electrical, see if you can get it free of charge.....if the above link is of no help to you.

[DMG]

If you need TSBs looked up stop by the shop. I have Alldata.

[cityslicker]

right on.