Miss at 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 > Miss at idle

Oconee Off-Road Now Offering Zone Off-Road Products!!!RIGID LED Light Blowout Sale - All Sizes, All Series, all USA Standard Chromoly Front Axle Shaft Kits with Dana 30 4

Reply
Unread 06-05-2014, 11:33 AM   #1
Jeepit85
Registered User
1985 CJ7 
 
Join Date: Feb 2010
Location: Wisconsin
Posts: 338
Miss at idle

I have installed a new 258. Motor misses at idle. Prior 258 did the same. I have had the Howell TB on both motors and new DUI installed on the new motor only. Old motor missed the same as the new. I have swapped out computers a several times and even had a modified one from Howell shipped to me. Same idle miss occurs.
What might be causing this?

__________________
85 CJ7, Howell TBI, Twin Stick, 4:10's, 35" Pitbull Rockers, Clifford 6=8, Detroits, Matkins Level II, BDS 4", Summers Brothers. Skynyrd rocks.
06 Rubicon
06 Lance Camper
02 Dodge Cummins
06 VW Jetta TDI
Jeepit85 is offline   Reply With Quote
Unread 06-05-2014, 11:37 AM   #2
CJ7-Tim
Real Jeeps have dents.
 
CJ7-Tim's Avatar
2000 XJ Cherokee 
 
Join Date: Apr 2002
Location: out in the garage - Minneapolis, Minnesota
Posts: 21,277
Does it stall at idle ? If not, I would call it good.


A 29 year old Jeep may have some quirks.
__________________
.

According to the National Shooting Sports Foundation, AR-15 sporting rifles account for nearly 20% of all U.S. firearms sales.

Progressive Liberalism: Bringing you new Healthcare ideas so wonderful, they have to include mandatory participation ......

Originally Posted by Ronald W. Reagan: Government is not the solution to our problem; Government is the problem.
CJ7-Tim is offline   Reply With Quote
Unread 06-05-2014, 02:39 PM   #3
Dngrs1
Registered User
1979 CJ7 
 
Join Date: May 2009
Location: Mohave Valley,AZ
Posts: 785
Did you reuse the plug wires?
__________________
I would rather have a tool I don't need, than need a tool I don't have.
Dngrs1 is offline   Reply With Quote
Unread 06-05-2014, 03:14 PM   #4
LumpyGrits
Registered User
1985 CJ7 
 
Join Date: Jul 2010
Location: The Mojave Desert Palmdale Ca. U.S.A.
Posts: 4,436
Spray the spark plug wires with soapy water. Does it get worst??
Ck ALL manifold bolts to be sure they are tight(vacuum leak).
LG
__________________
Have'n you along, is like loose'n 2 good men
LumpyGrits is offline   Reply With Quote
Unread 06-05-2014, 03:14 PM   #5
Jeepit85
Registered User
1985 CJ7 
 
Join Date: Feb 2010
Location: Wisconsin
Posts: 338
Does not stall at idle.
All new wires and plugs went on new motor.
__________________
85 CJ7, Howell TBI, Twin Stick, 4:10's, 35" Pitbull Rockers, Clifford 6=8, Detroits, Matkins Level II, BDS 4", Summers Brothers. Skynyrd rocks.
06 Rubicon
06 Lance Camper
02 Dodge Cummins
06 VW Jetta TDI
Jeepit85 is offline   Reply With Quote
Unread 06-05-2014, 03:17 PM   #6
LumpyGrits
Registered User
1985 CJ7 
 
Join Date: Jul 2010
Location: The Mojave Desert Palmdale Ca. U.S.A.
Posts: 4,436
Look for vacuum leaks then--
Make sure you don't have cross-firing inside the dizzy cap.
STILL- soapy water test the SP wires.
LG
__________________
Have'n you along, is like loose'n 2 good men
LumpyGrits is offline   Reply With Quote
Unread 06-05-2014, 04:31 PM   #7
CJ7-Tim
Real Jeeps have dents.
 
CJ7-Tim's Avatar
2000 XJ Cherokee 
 
Join Date: Apr 2002
Location: out in the garage - Minneapolis, Minnesota
Posts: 21,277
My CJ-7 and both my XJ's have a lumpy idle. I don't think the Jeep in-line 6 cylinder was ever known for it's smooth idle.
__________________
.

According to the National Shooting Sports Foundation, AR-15 sporting rifles account for nearly 20% of all U.S. firearms sales.

Progressive Liberalism: Bringing you new Healthcare ideas so wonderful, they have to include mandatory participation ......

Originally Posted by Ronald W. Reagan: Government is not the solution to our problem; Government is the problem.
CJ7-Tim is offline   Reply With Quote
Unread 06-05-2014, 04:45 PM   #8
LumpyGrits
Registered User
1985 CJ7 
 
Join Date: Jul 2010
Location: The Mojave Desert Palmdale Ca. U.S.A.
Posts: 4,436
Quote:
Originally Posted by CJ7-Tim View Post
I don't think the Jeep in-line 6 cylinder was ever known for it's smooth idle.
You would be wrong then.
Mine W/119+K miles, idles as smooth as any. Passes SMOG with ease.
BTW-the 258 was based on a tractor engine.
Any 'miss' at idle should be looked into.
LG
__________________
Have'n you along, is like loose'n 2 good men
LumpyGrits is offline   Reply With Quote
Unread 06-05-2014, 05:15 PM   #9
Matt1981CJ7
Web Wheeler
 
Matt1981CJ7's Avatar
1981 CJ7 
 
Join Date: May 2011
Location: Elbert, CO
Posts: 9,879
Quote:
Originally Posted by CJ7-Tim View Post
My CJ-7 and both my XJ's have a lumpy idle. I don't think the Jeep in-line 6 cylinder was ever known for it's smooth idle.
I have to disagree with this. Here's my 258, with 98K original miles, after I installed and tuned a Weber 38.

Turn the sound down and see if you can detect a single vibration at idle.

Matt

Matt1981CJ7 is offline   Reply With Quote
Unread 06-05-2014, 11:21 PM   #10
BagusJeep
Web Wheeler
 
BagusJeep's Avatar
1981 CJ7 
 
Join Date: Jul 2009
Location: Bali, Indonesia
Posts: 4,257
The Cherokee idles like a sewing machine, the J20 does not even with the Teamrush upgrade and new wires, Jeepputhi and Bagus are smooth as butter and stock.

So some do and some don't.
__________________
BagusJeep lives in Bali, the Land of Temples.
With a Jeep every prayer counts.

1981 CJ7 258ci - Bagusjeep
1984 CJ7 258ci - Puthijeep
1981 J20 258ci - Gladys
BagusJeep is offline   Reply With Quote
Unread 06-06-2014, 06:05 AM   #11
Mike Romain
Registered User
1986 CJ7 
 
Join Date: Nov 2007
Location: Off the Grid in Chester Grant, Nova Scotia, Canada
Posts: 11,820
How did you hook up your gas tank vent? When the air filter on mine is getting dirty, the idle gets lumpy. When I crack open the gas cap and the idle pops up and smooths right out, I know it is time for a new vent air filter.
__________________
Mike
86/00 CJ7 Laredo, 33x9.5 BFG AT's, 'glass nose to tail in '00, 'New' frame,wires and plumbing in '09. Carter BBD Carbed 4.0 HO in '10.
89 YJ Renegade. BBD Carbed 4.0 HO. Locked front and rear with 33x9.5 BFG AT's
Some Canadian Bush Jeep Runs and Build Photos: http://mikeromainjeeptrips.shutterfly.com (10 new albums added Sept 16/10)
Mike Romain is online now   Reply With Quote
Unread 06-06-2014, 11:51 AM   #12
steve1973
Registered User
1973 CJ5 
 
Join Date: Jan 2012
Location: Charlestown, Rhode Island
Posts: 93
My 73 with 46k miles and a imposter weber 34 is silky smooth at idle. You can balance a dime on edge on top of the hood at idle.
steve1973 is offline   Reply With Quote
Unread 06-06-2014, 02:36 PM   #13
Jeepit85
Registered User
1985 CJ7 
 
Join Date: Feb 2010
Location: Wisconsin
Posts: 338
Quote:
Originally Posted by Mike Romain View Post
How did you hook up your gas tank vent? When the air filter on mine is getting dirty, the idle gets lumpy. When I crack open the gas cap and the idle pops up and smooths right out, I know it is time for a new vent air filter.
Are they not vented to the canister? At least that is what I thought.
__________________
85 CJ7, Howell TBI, Twin Stick, 4:10's, 35" Pitbull Rockers, Clifford 6=8, Detroits, Matkins Level II, BDS 4", Summers Brothers. Skynyrd rocks.
06 Rubicon
06 Lance Camper
02 Dodge Cummins
06 VW Jetta TDI
Jeepit85 is offline   Reply With Quote
Unread 06-06-2014, 07:47 PM   #14
Mike Romain
Registered User
1986 CJ7 
 
Join Date: Nov 2007
Location: Off the Grid in Chester Grant, Nova Scotia, Canada
Posts: 11,820
Quote:
Originally Posted by Jeepit85 View Post

Are they not vented to the canister? At least that is what I thought.
Yes and the canister has to have a ported switched purge line to manifold vacuum or it saturates the charcoal with fumes which puts a vacuum on the gas tank. The canister has an air filter on the bottom for when it purges that is prone to getting filled with mud or dust which will do the same.
__________________
Mike
86/00 CJ7 Laredo, 33x9.5 BFG AT's, 'glass nose to tail in '00, 'New' frame,wires and plumbing in '09. Carter BBD Carbed 4.0 HO in '10.
89 YJ Renegade. BBD Carbed 4.0 HO. Locked front and rear with 33x9.5 BFG AT's
Some Canadian Bush Jeep Runs and Build Photos: http://mikeromainjeeptrips.shutterfly.com (10 new albums added Sept 16/10)
Mike Romain is online now   Reply With Quote
Unread 06-07-2014, 07:22 AM   #15
RWise
Registered User
1981 CJ5 
 
Join Date: Mar 2012
Location: Oakhurst, Oklahoma
Posts: 574
Mine would idle for a moment good and then start missing. Turn it off and look down its throat to see fuel standing in a puddle. For this I removed one of the 2 holes below the carb (made it into one large hole), re-tuned it and it now idles perfect! I used the OEM manifold from the 258 (on my 89 4.0) a hammer and chisel to open it up, left the roughness also. (gaskets/spacers cut away as well, open and say ahhhhhh)



I would suggest removing the manifold to do this, cut out the X first then the rest. Edit; my manifold is aluminum, cast iron would be more difficult, dont use a chisel here!

The 2150 carb I ended up with has no place for the return line, so I picked up a canister for the 89 xj engine which has no place for a vacuum line or return line. Its just a very large filter to let clean air into the tank. I have no tests to pass,,,,

Last edited by RWise; 06-07-2014 at 07:25 AM.. Reason: add/fix pic
RWise is offline   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.