Won't idle - JeepForum.com
Search  
Sign Up   Today's Posts
User: Pass: Remember?
Advertise Here
Jeep Home Jeep Forum Jeep Classifieds Jeep Registry JeepSpace Jeep Reviews Jeep Gallery Jeep Clubs Jeep Groups Jeep Videos Jeep Events Jeep Articles
Go Back JeepForum.com > Models > Jeep CJ Forum > Won't idle

FS: 2007-2013 Jeep Wrangler "HALO" Angel Eye KitFS: Wranger BRIGHT License Plate LED! Just $3! Great valueIntroducing our NEW JK tail light adapter wiring harness!!

Reply
Unread 08-09-2013, 06:20 PM   #1
RenoF250
Registered User
1985 CJ7 
 
Join Date: Sep 2011
Location: Foresthill, CA
Posts: 883
Won't idle

My CJ has gotten worse and worse at idle and now it is to the point that it that if you get below ~1k rpm you have to shut it off, start it, and rev through1k. Otherwise it just sits there and burlbes and backfires. I went to find the problem now that we are home and it was doing it then there was a click like and from a relay and it cleaned right up. I also notice that if I pull the hose of the green sensor on the firewall the engine speeds up and the vac increases. Any ideas of where to look? It is using the stock computer but has an MSD5 (uses the computer controlled coil output not right of the dist pickup like the 6).

RenoF250 is offline   Reply With Quote
Unread 08-09-2013, 07:07 PM   #2
melancholy35
Registered User
1985 CJ7 
 
Join Date: Jun 2012
Location: Preston, Maryland
Posts: 71
What motor?
melancholy35 is offline   Reply With Quote
Unread 08-09-2013, 07:45 PM   #3
RenoF250
Registered User
1985 CJ7 
 
Join Date: Sep 2011
Location: Foresthill, CA
Posts: 883
Quote:
Originally Posted by melancholy35 View Post
What motor?
4.2L

I just went out to play with it again and it was idling fine, I was checking the timing and then "click" again and it went to hell and the timing was bouncing all over the place.

What has the ability to tell the computer to go to crap mode.
RenoF250 is offline   Reply With Quote
Unread 08-09-2013, 08:31 PM   #4
melancholy35
Registered User
1985 CJ7 
 
Join Date: Jun 2012
Location: Preston, Maryland
Posts: 71
I would just do the nutter bypass that way you don't have to worry about the computer. Also what coil are you running? I was using the msd blaster and it ran like crap. I went back to the stock coil and no issues. There is also a mod In which you use a distributer cap from a ford which should also help.
melancholy35 is offline   Reply With Quote
Unread 08-09-2013, 08:32 PM   #5
melancholy35
Registered User
1985 CJ7 
 
Join Date: Jun 2012
Location: Preston, Maryland
Posts: 71
Are you letting it warm up before you check timing? Also are you pluging the dist vacuum line? What condition are your vacuum lines in?
melancholy35 is offline   Reply With Quote
Unread 08-09-2013, 09:25 PM   #6
LumpyGrits
Registered User
1985 CJ7 
 
Join Date: Jul 2010
Location: The Mojave Desert Palmdale Ca. U.S.A.
Posts: 3,815
When did you last rebuild the carb?
What mods has there been done to eng/carb/ign?
LumpyGrits is offline   Reply With Quote
Unread 08-09-2013, 10:18 PM   #7
RenoF250
Registered User
1985 CJ7 
 
Join Date: Sep 2011
Location: Foresthill, CA
Posts: 883
Quote:
Originally Posted by melancholy35 View Post
I would just do the nutter bypass that way you don't have to worry about the computer. Also what coil are you running? I was using the msd blaster and it ran like crap. I went back to the stock coil and no issues. There is also a mod In which you use a distributer cap from a ford which should also help.
The coil is a Summit that is supposedly correct for the MSD5. I have an MSD6 that needs to be sent in to get fixed. If that were working I would try it to rule out the computer.

It needs to be smogged in October and I don't think they will let me nutter it. Also, it runs great until the click.

I have the big team rush cap.
RenoF250 is offline   Reply With Quote
Unread 08-09-2013, 10:21 PM   #8
RenoF250
Registered User
1985 CJ7 
 
Join Date: Sep 2011
Location: Foresthill, CA
Posts: 883
Quote:
Originally Posted by LumpyGrits View Post
When did you last rebuild the carb?
What mods has there been done to eng/carb/ign?
About a year and a half ago. Engine and carb are stock. Ignition is team rushed and MSD5 with Summit coil in place of existing coil. There is also a relay to power the MSD5 that is switched off the red coil wire. It can click but when I shut it off the engine dies as expected so I do not think it is the click I am hearing. That is even louder, sounds like an A/C compressor clutch.
RenoF250 is offline   Reply With Quote
Unread 08-09-2013, 10:24 PM   #9
RenoF250
Registered User
1985 CJ7 
 
Join Date: Sep 2011
Location: Foresthill, CA
Posts: 883
Quote:
Originally Posted by melancholy35 View Post
Are you letting it warm up before you check timing? Also are you pluging the dist vacuum line? What condition are your vacuum lines in?
Yes, it was warmed up when I timed it but this time I was just checking to see what the timing was doing and did not adjust it. I also wanted to make sure it was not bouncing around indicating a bad timing chain. It was unremarkable until the click then it bounced all over.

Take it for a drive a bit ago and it ran perfect at all RPMs and did not exhibit the problem at all.
RenoF250 is offline   Reply With Quote
Unread 08-09-2013, 10:52 PM   #10
86cj74.2L
Web Wheeler
 
86cj74.2L's Avatar
2004 WJ 
 
Join Date: Jul 2006
Location: Stouchsburg, PA
Posts: 5,780
Quote:
Originally Posted by RenoF250

Yes, it was warmed up when I timed it but this time I was just checking to see what the timing was doing and did not adjust it. I also wanted to make sure it was not bouncing around indicating a bad timing chain. It was unremarkable until the click then it bounced all over.

Take it for a drive a bit ago and it ran perfect at all RPMs and did not exhibit the problem at all.
Are you able to post a picture of what you disconnect to make it happy?

That click could be a relay for idle control near the battery, or one of the three vacuum solenoids on valve cover.

If its one of the valve cover ones.......they could be open to atmosphere. Creating a vacuum leak which leans out the idle.

When its running ruff spray some brake cleaner around the vacuum lines. You will know when you find it.
86cj74.2L is online now   Reply With Quote
Unread 08-10-2013, 09:25 AM   #11
LumpyGrits
Registered User
1985 CJ7 
 
Join Date: Jul 2010
Location: The Mojave Desert Palmdale Ca. U.S.A.
Posts: 3,815
I would not use brake cleaner around those PLASTIC vacuum switch fittings etc. that AMC put all over our Jeeps.
I have used very soapy water in a spray bottle for this, with good results.
You will see the bubbles get pulled inside where the leak is.
LG
LumpyGrits is offline   Reply With Quote
Unread 08-10-2013, 10:41 AM   #12
RenoF250
Registered User
1985 CJ7 
 
Join Date: Sep 2011
Location: Foresthill, CA
Posts: 883
Quote:
Originally Posted by 86cj74.2L View Post
Are you able to post a picture of what you disconnect to make it happy?

That click could be a relay for idle control near the battery, or one of the three vacuum solenoids on valve cover.

If its one of the valve cover ones.......they could be open to atmosphere. Creating a vacuum leak which leans out the idle.

When its running ruff spray some brake cleaner around the vacuum lines. You will know when you find it.
I wish I knew what it was that disconnects, I just hear a click. I will try disconnecting the things you mention and see if any of them do it. I generally pinch the lines to see if it makes a difference. I do not think this is a vacuum port opening though because when it is running good I can pull a hose off and it does have nearly the same effect.
RenoF250 is offline   Reply With Quote
Unread 08-10-2013, 12:52 PM   #13
RenoF250
Registered User
1985 CJ7 
 
Join Date: Sep 2011
Location: Foresthill, CA
Posts: 883
Of course now that I am home it won't do it. I did not see a relay by the battery but there are two light blue ones on the back of the engine. I unplugged each individually with no effect (kept idling well) and the vacuum sensors on the firewall. If I can get it to do it again I will try unplugging them again and see if it starts running well. Nothing quite as fun as troubleshooting an intermittent.
RenoF250 is offline   Reply With Quote
Unread 08-10-2013, 02:01 PM   #14
RenoF250
Registered User
1985 CJ7 
 
Join Date: Sep 2011
Location: Foresthill, CA
Posts: 883
Not likely related but I was running it trying to get it to do it again and shut it off and it just kept running like nothing happened. Opened the hood and checked the relay to the MSD it was still getting ~4.9V from the coil wire so it was still on.
RenoF250 is offline   Reply With Quote
Unread 08-10-2013, 02:05 PM   #15
86cj74.2L
Web Wheeler
 
86cj74.2L's Avatar
2004 WJ 
 
Join Date: Jul 2006
Location: Stouchsburg, PA
Posts: 5,780
When Grammys CJ kept running with the key in her hand it took replacing the starter solenoid
To fix it.
86cj74.2L is online now   Reply With Quote




Jeep, Wrangler, Cherokee, Grand Cherokee, and other models are copyrighted and trademarked to Jeep/Chrysler Corporation. JeepForum.com is not in any way associated with Jeep or the Chrysler Corp.