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Unread 08-12-2010, 06:54 PM   #1
tjdriver
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heat soak issue on 4.0L

i know there are a few jeepers out there with the heat soak issue on the 4.0.
i'm one of them. i read and applied the tsb and to no avail. time after time my jeep has hesitated and ran rough after running to the store. i've read a few threads that say the ethanol content in gas is partially to blame.

i found some ethanol free gas at a local station. it was $.10 more than every other gas station around but so far it is worth it. i have only burned a quarter of a tank out so far but i have not had the rough idle after a quick run to the store. i'm going riding with my jeep club this weekend in MS and hope to ahve the same results. i will report back when i get back on sunday.

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Unread 08-12-2010, 07:10 PM   #2
jeepin-gheenoe
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sounds good man! let us know!

i dont have this problem with my jeep...but my 1981 15hp evinrude on my gheenoe...exact same senerio with yalls jeeps, i hope this is why she runs bad when hot.

thanks again!
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Unread 08-12-2010, 07:47 PM   #3
BYuen
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Hey you'll get better gas mileage too with ethanol free gas! I've tried for the life of me but could not find a gas station around my area that doesn't have the ethanol junk in it
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Unread 08-12-2010, 09:15 PM   #4
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I have had issues with heat soak/vapor lock twice...both times on the trail with +90 degree temps. Try starting your Jeep with the AC on when you are having those issues. It makes it SOOO much worse
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Unread 08-12-2010, 09:25 PM   #5
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I thnk that was the issue I've been having with the rough idle was heat soak. It's been 90+ degrees here in NC and it just stopped doing it today...after I floored it a few times Idles great now.
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Unread 08-12-2010, 09:27 PM   #6
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Quote:
Originally Posted by 2006_Sport View Post
I thnk that was the issue I've been having with the rough idle was heat soak. It's been 90+ degrees here in NC and it just stopped doing it today...after I floored it a few times Idles great now.
Yup, you gotta really blow that **** out...
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Finesse in crawling looks way cooler than momentum.
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Unread 08-12-2010, 09:50 PM   #7
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what is "heat soak" in the jeep world? I only know of it in turbo charged applications... Heat soak dealt with intercoolers getting hot from being parked and the heat of the engine soaking them. More prominent in top mount intercooler situations.....
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Unread 08-13-2010, 05:45 AM   #8
tjdriver
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i went to have my echo weedbeater fixed and they guy told me the diaphragm was shot. he said it's the ethanol content in the gas that makes them wear out prematurely. i told him that chit is making my motor in my jeep unhappy and he said there was a gas station just down the road that has ethanol free. i filled up that day and she's doing good so far.


--------------------------------------------------------------------------------

Fuel System - Hot Start Misfire/MIL ON/DTC's/Rough Idle

NUMBER: 18-031-03

GROUP: Vehicle Performance

DATE: Sep. 05, 2003

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 ********S HAVE BEEN USED TO HIGHLIGHT REVISIONS.

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 (90°F) 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.

PARTS REQUIRED

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).
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Unread 08-13-2010, 09:04 AM   #9
BYuen
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I wrapped some tin foil around my #3 injector. I think it helped a little, but it's not enough. I'm gonna have to wrap the rest of the injectors and the entire injector rail and see how that goes. Or I guess I could spend some money and get that TSB insulator lol
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Unread 08-13-2010, 09:08 AM   #10
pwcracer
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This is exactly what my Jeep does on the trail. It's such a PITA I don't like shutting my jeep off..
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Unread 08-13-2010, 10:04 AM   #11
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i just floor the gas pedal after the heatsoak rough idle. once it hits near WOT, the fuel moves through and the MAP sensor takes a reading, all is normal.
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Unread 08-13-2010, 10:14 AM   #12
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Quote:
Originally Posted by Unlimited04 View Post
i just floor the gas pedal after the heatsoak rough idle. once it hits near WOT, the fuel moves through and the MAP sensor takes a reading, all is normal.
Exactly what I do.
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Quote:
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Finesse in crawling looks way cooler than momentum.
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Unread 08-13-2010, 10:21 AM   #13
Dogman
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That's been my experience on the trail as well. I had someone ask me if my Jeep was carbureted - totally annoying
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Unread 08-15-2010, 05:27 PM   #14
tjdriver
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^^^^ lol.

my jeep ran a heck of alot better and i had better mpgs off the non ethanol gas.
we played in a huge sand pit and it was hot as you know what until it started pouring.
i didn't hesitate to shut my jeep off when we stopped for a few minutes like i normally would.
i did have a slight hesitation upon start up, but no where near what i had before. it only had the hesitation once
or twice, but like i said it poured on us. i'm going to continue running the ethanol free gas in the jeep.
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Unread 08-15-2010, 06:26 PM   #15
tjdriver
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forgot to add that when i filled up with ethanol free i was at 1/4 of tank of the ethanol stuff. i just filled up again and figure it may be out after this tank or the next and i should see true results.
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