258 Idle Issue - 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 > 258 Idle Issue

Rough Country Deals at JeepHut.comSave at JeepHut on Smittybilt Soft topsUp to $75 Cash Back on Your ARB Fridge Freezer Purchase

Reply
Unread 08-27-2013, 06:59 PM   #1
Looby
Registered User
1986 CJ7 
 
Join Date: Apr 2008
Location: Atlanta
Posts: 8
258 Idle Issue

Hey guys I am having a problem that I cannot figure out. I know there are ten thousand idle problem threads but none cover my problem.

Background:
258 I6 ~250k miles
Motorcraft 2100 1.08
MSD Digital 6 (CDI type ignition)
MSD TFI coil
Taylor 8.2mm wires
Teamrush cap and rotor
Timing set to 8-9 degrees no vacuum advance
Autolite copper plugs gapped .055
all vacuum lines removed except pcv and breather
all computer and other misc. wires removed
all emissions related components removed. (excluding converter)
K&N 9" custom air cleaner


Problem:
SOMETIMES at idle motor runs very poorly. feels like it is not running on all cylinders. This is not a constant condition. it comes and goes with no discernible pattern. one minute rough then at the next stoplight smooth as a beamer... when rough I am talking the jeep shakes like a beast. I did read somewhere that it could be the egr opening for some odd reason at idle but with no vacuum hooked to it this should not be the case.

There are no vacuum leaks to be found.

Now the thing is... it runs awesome!! anything above idle and it hauls like crazy. can stomp the gas in any gear and it will pull hard. does not miss, hesitate, sputter, or anything that would indicate other problem. I highly recommend the MC2100 swap to anyone who is thinking about it. It has breathed a whole lot of new life into my tired old jeep


Side Note:
After installing the carb I noticed it can be hard to start after a short stop like going into a store for 10-20 mins. Engine turns over and over like it is not getting gas. fuel pressure read stable last time I checked it 4-5 weeks ago. on the carter there was a float needle type one way valve in the main fuel line that was not able to be reused with the motorcraft carb. could the gas be draining out of the fuel line and then the fuel pump has to repump all that gas up the line?



Thanks for any direction.

Looby

Looby is offline   Reply With Quote
Unread 08-27-2013, 07:16 PM   #2
kovic
Registered User
1983 CJ5 
 
Join Date: Apr 2012
Location: Grand Rapids, MI
Posts: 600
First thing i noticed is your spark plug gap is massive. How old is your Fuel Filter, any spark plug wires crossed?

kov
kovic is offline   Reply With Quote
Unread 08-27-2013, 07:50 PM   #3
Looby
Registered User
1986 CJ7 
 
Join Date: Apr 2008
Location: Atlanta
Posts: 8
Hey. From what I have read gap should be .035 stock and about .050-.060 with cdi ignition and tfi coil. i figured split the difference at .055.

fuel filter is 2-3 weeks old

wires are not crossed.

I really do not understand what could cause such an erratic problem. if it was constant that would be one thing but given the particular nature of this rough idle I am utterly at a loss


Looby
Looby is offline   Reply With Quote
Unread 08-27-2013, 08:20 PM   #4
kovic
Registered User
1983 CJ5 
 
Join Date: Apr 2012
Location: Grand Rapids, MI
Posts: 600
Rebuild the carb lately?

kov
kovic is offline   Reply With Quote
Unread 08-27-2013, 08:48 PM   #5
SCSEAJAYSEVEN
Registered User
1978 CJ7 
 
Join Date: Jul 2004
Location: Summerville, SC, South Carolina
Posts: 76
Try closing your plug gap to .045 and see if that makes a difference. I have a very similar setup as you, except I do have a vacuum line to the distributor. I was playing around with different plug gaps, and anything over .050 didn't run right. I now run about .043-.044, and that seems right for my 258...
At 250K miles, I'll bet your timing chain has plenty of slack in it, causing the timing to fluctuate, causing some of the rough idle. Under power, the slack in not there, so the timing is constant...
__________________
KB4ERT
1978 CJ-7 258 4.2L
1982 DJ-5L 151 2.5L
SCSEAJAYSEVEN is offline   Reply With Quote
Unread 08-27-2013, 09:06 PM   #6
Looby
Registered User
1986 CJ7 
 
Join Date: Apr 2008
Location: Atlanta
Posts: 8
Carb was purchase as a swap from ehrmannmp (ebay user name) and rebuilt by him along with all the parts needed for the swap. installed 2-3 weeks ago.

I replaced plugs today swapping from old plugs to new ones (old ones were stock gap). the new plugs are gapped to .055 but the problem existed before the change.

timing chain has not been done in..... god forever. recommendations as to best place to look or brand to get?

Edit:
I do notice COMP Cams makes a timing set and I was planning on running one of their cams later on. opinions on this set?

http://www.compperformancegroupstore..._Code=A6Timing

http://www.amazon.com/COMP-Cams-3219...ype=automotive

Looby
Looby is offline   Reply With Quote
Unread 08-27-2013, 10:15 PM   #7
LumpyGrits
Registered User
1985 CJ7 
 
Join Date: Jul 2010
Location: The Mojave Desert Palmdale Ca. U.S.A.
Posts: 4,618
Get your plug gap back down to .045".
What AL plugs are you using? 985's??
Start the engine. Spray the SP wires with soapy(VERY)water. Does the miss get worst?
Now spray(engine still run'n)all around the intake/exhaust manifolds. Any change?
LG
__________________
Have'n you along, is like loose'n 2 good men
LumpyGrits is offline   Reply With Quote
Unread 08-28-2013, 12:15 AM   #8
86cj74.2L
Web Wheeler
 
86cj74.2L's Avatar
2004 WJ 
 
Join Date: Jul 2006
Location: Stouchsburg, PA
Posts: 6,436
With 250k on the clock I'd do a compression check.

It could be dropping a cylinder or two at times causing the ruff idle.

That MSD should fire those plugs at .055 all day long. In the beginning of using the MSD on Grammys CJ I had that .055 gap on the stock cap and rotor for three years with no problems. I am gapped down to .045 now though with the biggy ford cap and rotor and jeep 4.0l wire set.

Since you say your idle problem was before the plug swap. You changed your carb to the MC for the same idle problem? Thinking it was the dreaded carter syndrome?
86cj74.2L is offline   Reply With Quote
Unread 08-28-2013, 04:46 AM   #9
Looby
Registered User
1986 CJ7 
 
Join Date: Apr 2008
Location: Atlanta
Posts: 8
LG - I will try this tomorrow when I am off. I assume this is to check for bad wires and vacuum leaks? upon install of carb I sprayed carb cleaner all around base and everything to check for leaks and none were found. I hope the wires are not bad as they were installed at the same time as everything else. 2-3 weeks ago.


I did the MC2100 swap for a variety of reasons.

1. this thing would barely run and under any type of load the valves would all of a sudden clatter like a ***** and I would lose all power. I was not able to use 5th gear at all and anything above 45mph was damn near impossible. now I can do almost 80mph with the valve clatter only under heavy load.(accel uphill in 5th)

2. I was also not able to get the thing to ever idle because the idle adjustments on the carter did not even touch anything rendering them useless.

3. Very hard to start.


Being that there were soo many different issues I cannot say 100% that this was not present before the carb swap.


Looby
Looby is offline   Reply With Quote
Unread 08-28-2013, 06:48 AM   #10
86cj74.2L
Web Wheeler
 
86cj74.2L's Avatar
2004 WJ 
 
Join Date: Jul 2006
Location: Stouchsburg, PA
Posts: 6,436
Do a compression check.
86cj74.2L is offline   Reply With Quote
Unread 08-28-2013, 08:48 AM   #11
LumpyGrits
Registered User
1985 CJ7 
 
Join Date: Jul 2010
Location: The Mojave Desert Palmdale Ca. U.S.A.
Posts: 4,618
Again, what # AL plug did you use?
Pull each plug and 'read' it.
LG
__________________
Have'n you along, is like loose'n 2 good men
LumpyGrits is offline   Reply With Quote
Unread 09-15-2013, 09:35 AM   #12
Looby
Registered User
1986 CJ7 
 
Join Date: Apr 2008
Location: Atlanta
Posts: 8
sorry guys grandfather has been in hospital so have been stressed for time.

compression test results


#1 - 173 & 173
#2 - 173 & 176
#3 - 173 & 175
#4 - 168 & 170
#5 - 176 & 178
#6 - 178 & 178


plugs are all 985 autolite

i am going to order new cloyes timing set and replace that Beachwear its been 10-11 years since it was done last. any other suggestions or help?

Looby
Looby is offline   Reply With Quote
Unread 09-15-2013, 09:59 AM   #13
LumpyGrits
Registered User
1985 CJ7 
 
Join Date: Jul 2010
Location: The Mojave Desert Palmdale Ca. U.S.A.
Posts: 4,618
Rebuild the carb.
Check to be sure all manifold bolts are tight.
Take a vacuum reading from carb base.
Check the carb's float level.
LG
__________________
Have'n you along, is like loose'n 2 good men
LumpyGrits is offline   Reply With Quote
Unread 09-15-2013, 10:28 AM   #14
Looby
Registered User
1986 CJ7 
 
Join Date: Apr 2008
Location: Atlanta
Posts: 8
Carb is brand new. why rebuild a brand new part?

all bolts are tight. no vacuum leaks can be found. (via spraying around Carb with Carb cleaner)

i will check vacuum level at Carb but what should it be?

thanks
Looby
Looby is offline   Reply With Quote
Unread 09-15-2013, 10:48 AM   #15
LumpyGrits
Registered User
1985 CJ7 
 
Join Date: Jul 2010
Location: The Mojave Desert Palmdale Ca. U.S.A.
Posts: 4,618
16-19 in/hg and steady.
Spray the intake manifold where it bolts to the head with very soapy water. v'leak will pull the soap inside and the engine then 'stumbles' some.
Why do you think the carb is NOT the issue? Just 'cause someone rebuilt it, doesn't mean it was rebuilt 'rite'.
Again, check the carb's float level.
Get a copy of the REAL, FSM. It will show you how to do this. Hayne's and the like, don't cut-it........
LG
__________________
Have'n you along, is like loose'n 2 good men
LumpyGrits 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.