Heat Soak Misfire fix


Go Back   Jeep Cherokee Forum > General Technical Forum > Technical Articles


CherokeeTalk.com is the premier Chrysler Jeep Cherokee Forum on the internet. Registered Users do not see the above ads.
Reply
 
LinkBack Thread Tools Display Modes
Old 03-30-2010, 07:57 PM   #1
muddeprived
Retired Moderator
Feedback Score: 7 reviews
 
muddeprived's Avatar
 
Join Date: Sep 2008
Location: ground, Planet Earth
Posts: 10,177
Default Heat Soak Misfire fix

Some of the 4.0's in the xj's are plagued with misfire issues due to heat soak. I been through a number of fixes for this issue and nothing has helped. I poured in alot of money to get this damn misfire cured but it's like cancer, no absolute cure for it, or so it seems. But anyways the idea of installing a delay timer to my stock e-fan came up on naxja and i was recommended a timer to use. I bought it but had no idea how to wire it up so it got put off for a couple months. After dealing with the misfire more and more, I decided it's time to tackle it. I asked the guys on naxja and 4.3LXJ (plus some others) here to walk me through the install and it came out pretty good. Wasn't as hard as I thought.

We started with this timer:

ELK-960 Delay Timer

and this setup:



Did all the wiring over a period of 8 hrs. Yeah it took a while but I wanted a neat install, not just some wires all over the place.

These pictures are the pre-testing phase of the wire-up to see if it works first.

Tapped into the fan wire:



Newish loom running across the motor contains 6 wires for the timer setup:



The relay mounted on the firewall (it's now cleaned up and no web of wires)



Going to the battery with a temporary circuit breaker:


where i planned to mount the timer (behind glove box):



tapping into the stock fuse box:



Testing: 10 second timer


Final dash setup:


Final test: 50 second timer




So far no misfire in the past two days of driving. I can't get it to do it now. Maybe this is the fix after all........but too early to tell.

Thought i'd share for those who are going through the same thing.



Chris


__________________
oe kame ngenga


http://www.ironman4x4fab.com/index.html :thumbsup:

Last edited by muddeprived; 04-13-2010 at 07:27 PM.
muddeprived is offline   Reply With Quote
Sponsored Links
Advertisement
 
Old 03-30-2010, 08:34 PM   #2
4.3L XJ
Veteran
Feedback Score: 0 reviews
 
4.3L XJ's Avatar
 
Join Date: Dec 2008
Location: Chico, CA
Posts: 5,667
Default

Glad it is working Mud. Thanks for the plug. Lots of fellas will be interested in this fix.
4.3L XJ is offline   Reply With Quote
Old 03-30-2010, 09:13 PM   #3
2000XJ
Retired Moderator
Feedback Score: 6 reviews
 
2000XJ's Avatar
 
Join Date: Nov 2008
Location: Parsippany, New Jersey
Posts: 7,279
Default

Chris great idea, and good write-up. Thanks!
__________________
Dave
North Jersey Jeep Club

Trail Rig: 2000 XJ w/ 4.5" Lift, 35's, beadlocks, 4:1, Caged, Locked XJ D44 Rear, Locked D30, and a bunch of other things

Daily Driver: '07 A4 2.0T Quattro 6-speed

Former Daily Drivers: WK2, XJ, 4Runner, XJ, E30

Former Former Daily Driver: 2001 XJ Daily Driver, 2" BB, 245/70R16 AT's on Moabs
2000XJ is offline   Reply With Quote
Old 03-31-2010, 09:22 AM   #4
Quinn
Senior Member
Feedback Score: 1 reviews
 
Quinn's Avatar
 
Join Date: Oct 2008
Location: Springfield, MA
Posts: 600
Default

I'm not really sure how or why this could help, seeing as after the vehicle is turned off, the coolent obviously does not flow through the radiator, so the fan would just cool the coolent that is sitting in the radiator....?

Please explain.
__________________
4.0 - AX15 - 231 - 8.25 - 31's
Quinn is offline   Reply With Quote
Old 03-31-2010, 09:44 AM   #5
88fadedglory
Veteran
Feedback Score: 0 reviews
 
Join Date: Mar 2009
Posts: 1,536
Default

Quote:
Originally Posted by Quinn View Post
I'm not really sure how or why this could help, seeing as after the vehicle is turned off, the coolent obviously does not flow through the radiator, so the fan would just cool the coolent that is sitting in the radiator....?

Please explain.
It's called thermosiphon.

Hot liquids and gasses tend to be lighter than their colder counterparts so, heat rises and cool sinks. It's the principle of the hot air balloon, btw.

In this case, the engine continues to heat soak coolant which wants to rise in the block which pushes coolant towars the radiator where it's cooled by the air and flows back to the engine for more heating.

The fan will aid the cooling and reduce the heat getting to the fuel system.

Early cars in the teens and 20's used the system because you didn't need a pump, but many had a strong tendency to overheat under load because the flow was too slow.
88fadedglory is offline   Reply With Quote
Old 03-31-2010, 10:30 AM   #6
muddeprived
Retired Moderator
Feedback Score: 7 reviews
 
muddeprived's Avatar
 
Join Date: Sep 2008
Location: ground, Planet Earth
Posts: 10,177
Default

The exhaust manifold is right under the intake manifold and fuel line/injectors. All this heat is coming off the exhaust manifold and heating the gas causing it to vaporize in the chambers. This causes a misfire on the next startup. When I leave the hood open the jeep never misfires cuz the heat can escape. Leaving the fan on will have it continue blowing air at the exhaust manifold and injection system, keeping the hot air flowing out of the vents and under the motor. Put your hand behind the power steering pump while the fan is running and you'll feel a large flow of air and it's aimed at the exhaust manifold.
__________________
oe kame ngenga


http://www.ironman4x4fab.com/index.html :thumbsup:
muddeprived is offline   Reply With Quote
Old 03-31-2010, 04:57 PM   #7
Quinn
Senior Member
Feedback Score: 1 reviews
 
Quinn's Avatar
 
Join Date: Oct 2008
Location: Springfield, MA
Posts: 600
Default

Gotcha, makes sense.
__________________
4.0 - AX15 - 231 - 8.25 - 31's
Quinn is offline   Reply With Quote
Old 03-31-2010, 05:32 PM   #8
HillBilly
Experienced
Feedback Score: 0 reviews
 
HillBilly's Avatar
 
Join Date: Mar 2010
Location: Bluegrass Region, KY
Posts: 207
Default

Thanks guys for all that info. Definitely something to think about.
That's one more thing added to my list.
__________________
The Second Amendment:
USA's original Homeland Security
HillBilly is offline   Reply With Quote
Old 04-03-2010, 03:40 PM   #9
xjman4life
Jr Member
Feedback Score: 1 reviews
 
xjman4life's Avatar
 
Join Date: Sep 2009
Posts: 351
Default

I would like to personally thank everyone involved in this project because I saw how long Mud worked on this and it would not have been possible without the guys on NAXJA.
__________________
2001 XJ Silver 178,225 miles
3 Rusty's Full Packs
DD 30 inch Pro Comp AT's
Off Road 31 inch Maxxis Bighorns
Skyjacker Hydros
Front Tow Hooks
Off road scars were free.
xjman4life is offline   Reply With Quote
Old 04-13-2010, 07:15 PM   #10
rockcrusher
Senior Member
Feedback Score: 0 reviews
 
rockcrusher's Avatar
 
Join Date: Jan 2010
Location: Loganville, Walton County Georgia
Posts: 759
Default

Great write up
rockcrusher is offline   Reply With Quote
Old 04-13-2010, 07:26 PM   #11
muddeprived
Retired Moderator
Feedback Score: 7 reviews
 
muddeprived's Avatar
 
Join Date: Sep 2008
Location: ground, Planet Earth
Posts: 10,177
Default

Thanks.


It's been two weeks and I've had zero misfires. It's rather strange to start up the rig and have it run normally. Gonna take some getting used to......



I did have a small issue with the delay timer though. I couldn't get the adjustment wheel set to 3 minutes. It would only do 50 seconds and 4.5 minutes or longer. ELK was cool about it and sent me another timer free and it worked great. Now I have it dialed for 2.5 minutes.
__________________
oe kame ngenga


http://www.ironman4x4fab.com/index.html :thumbsup:
muddeprived is offline   Reply With Quote
Old 04-13-2010, 08:32 PM   #12
4.3L XJ
Veteran
Feedback Score: 0 reviews
 
4.3L XJ's Avatar
 
Join Date: Dec 2008
Location: Chico, CA
Posts: 5,667
Default

Glad to hear it Mudd. I always thought that it needed to be set for a longer time period than what you started with
__________________
230 hp 4.3L Chevy
Built 4L60E with manual lockout
Atlas 4 speed
Griffin radiator
On board air
Warn 9.5ti on custom bumper
7.5" RE front and bastard pack rear on custom long arms
31 gal. gas tank
4.3L XJ is offline   Reply With Quote
Old 11-21-2010, 10:01 AM   #13
ChroniCough
Newbie
Feedback Score: 0 reviews
 
Join Date: Nov 2010
Location: Houston, Texas
Posts: 1
Default

Hi Mudd, i have been following you posts allll around at a couple sites and i am having the same exact issue as you.

I would like a parts list and maybe where you purchased the stuff to do the timer for you EC fan!

Thanks for all the hard work.
ChroniCough is offline   Reply With Quote
Old 11-21-2010, 10:50 AM   #14
muddeprived
Retired Moderator
Feedback Score: 7 reviews
 
muddeprived's Avatar
 
Join Date: Sep 2008
Location: ground, Planet Earth
Posts: 10,177
Default

What year is your jeep?

This is the timer I used:

ELK-960 Delay Timer Module
You can google "elk-960" and you'll find a couple places to order it from.

As for the parts I used, I have a huge assortment of electrical supplies from building my RC cars and trucks so i can't really remember where all that junk came from but Radio Shack has pretty much everything you will need including which button/switch you need/prefer. Advance auto parts has the relay and thick guage wire needed. Basically I used what I had around and if I needed something I went to the store and grabbed it. I made quite a few trips lol.

Use the diagram in my original post to see how many connectors and how much wiring you will need. Basically you just have to mount the relay and the elk timer somewhere and then route wires to everything. The colored wires are what you will be working with, not the wiring on the left so it's easier than it looks.

Sorry if I can't give you a full list of all parts.
__________________
oe kame ngenga


http://www.ironman4x4fab.com/index.html :thumbsup:
muddeprived is offline   Reply With Quote
Old 02-21-2011, 10:31 AM   #15
furiouschapa
Newbie
Feedback Score: 0 reviews
 
Join Date: Feb 2011
Location: Austin, TX
Posts: 6
Default would a thermostatic work??

I am also having this issue and am tryingt o tackle it before the summer days in Texas.....Any thoughts on if a thermostatic would work just as well as the delay timer??


furiouschapa is offline   Reply With Quote
Sponsored Links
Advertisement
 
Reply

Go Back   Jeep Cherokee Forum > General Technical Forum > Technical Articles
Thread Tools
Display Modes

Similar Threads
Thread Thread Starter Forum Replies Last Post
88 XJ Misfire/hesitation....HELP!!!!!! Da9R00d Jeep Cherokee Stock Technical Forum 17 10-26-2010 11:36 PM
cylinder misfire...help! jeeper435 Jeep Grand Cherokee Technical Forum 17 02-20-2010 07:14 PM
#1 Cylinder misfire code on stock 4.0 - Help! gearhead Jeep Cherokee Stock Technical Forum 3 07-01-2009 04:23 PM
damn misfire! muddeprived Jeep Cherokee Modified Technical Forum 2 03-17-2009 08:21 AM
misfire issues xj.. plz help me 99 xj hondaguy Jeep Cherokee Stock Technical Forum 1 01-15-2009 07:58 PM




All times are GMT -6. The time now is 01:53 PM.



Copyright ©2000 - 2014, Jelsoft Enterprises Ltd
-->

Garage Plus vBulletin Plugins by Drive Thru Online, Inc.

Content Relevant URLs by vBSEO 3.6.0