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Misfire/popping at Idle
#1601572
03/31/14 10:55 PM
03/31/14 10:55 PM
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Joined: Jan 2003
Posts: 660
River Falls, WI
urdustd
OP
mopar
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OP
mopar
Joined: Jan 2003
Posts: 660
River Falls, WI
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I have a 360 I built a few years ago for my 74 Duster 360. It has an older Hughes/Engle cam HE2430, newer style MP adj mechanical advance distributor and Edelbrock heads, intake and carb. It has served me well, but probably doesn't have much more than 10K miles total on it. Just an occasional back-n-forth to work and weekend cruiser. I recently started misfiring at idle. It seems pretty good above 1500-2000 rpm, although it might be missing occasionally there too. The misfires is getting worse with time. I have concentrated on the ignition system as I figured it was a plug, wire, cap, or phasing issue. I had the engine out a while ago replacing steering box, headers, torque converter, and an oil pan leak. When I put it back together a buddy talked me into re-lubing the cam with cam lube as it was out for quite some time. It was right after this the misfire started and as I said it has continually gotten worse.
I changed, plugs, cap, wires as I went to RobbMC's cap adapter I bought from him a few years back. In addition I changed from an older orange box to a factory style and my Blaster 2 coil to an Echlen factory replacement coil. I also check cam phasing, which was off, and adjusted it by modifying the cap adapter to line the reluctor, rotor and #1 spark plug terminal on the cap. I haven't changed the pickup coil which is still an option I guess. There appears to be no vacuum leaks, the plugs are a little dark, but not bad. I went through the carb and thoroughly cleaned it. I also took a close look at all the harness under the hood (it was replaced with a Year1 harness a few years ago) and dash to make sure there are good connections, etc. It still pulls hard when got on and revs freely.
I'm stumped and am worried that putting the cam lube on wasn't such a good idea. Thinking I might have lost a lobe on the camshaft. It makes no funny noises, internally.
Does anyone have any ideas? I'm open to suggestions. I will probably try the pickup coil this weekend and probably pull the valve covers to see if there are any issues with the adjusters and rockers (Crane Golds). That might lead me to a cam issue.
Thanks in advance for anyone's help!
Jim
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Re: Misfire/popping at Idle
[Re: urdustd]
#1601575
03/31/14 11:23 PM
03/31/14 11:23 PM
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Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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It sounds like a weak coil.. if the voltage is up on it then it works better... I know you said you changed it but we all know a new part doesnt mean its right or it could still be the wires 
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Re: Misfire/popping at Idle
[Re: Crizila]
#1601579
04/01/14 03:27 AM
04/01/14 03:27 AM
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Joined: Jan 2003
Posts: 660
River Falls, WI
urdustd
OP
mopar
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OP
mopar
Joined: Jan 2003
Posts: 660
River Falls, WI
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Quote:
Quote:
Do a leak-down test.
 or compression test. Gotta start somewhere and a good place is always the mechanicals. Another good place to start is with a vacuum gauge. www.secondchancegarage.com has a great how to use / read a vacuum gauge section.
To answer a few questions.
Water in fuel - I don't think so. I always run the piss they call 91 octane out west here. But when I started to have this issue I put 10 gallons of 100 octane no lead with no change. I also added a can of Sea Foam. So probably unlikely, but I could pump the tank empty and put fresh fuel in.
Timing chain slop - I'm sure there is some as I didn't put a tensioner on it, but I used a Cloyes roller chain. I was thinking this might be why it was so out of phase. Hard to say, but there doesn't seem to be a lot of slop when turned by hand a few degrees each direction.
Coil - easy change. Might be able to borrow one to try.
Leak down/compression check- I don't have the tools for a leak down test, but I do have a compression gauge. That would be pretty easy and not a bad test to at least start with.
I think I will still pull the valve covers and change the pickup coil since I have a new one in the garage.
If anyone else has ideas I'm all ears!
Here is a video of marginal quality that I took some time ago when this started. You can hear it at idle but not when revved.
Video link
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Re: Misfire/popping at Idle
[Re: urdustd]
#1601580
04/01/14 03:36 AM
04/01/14 03:36 AM
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Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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Quote:
Quote:
Quote:
Do a leak-down test.
or compression test. Gotta start somewhere and a good place is always the mechanicals. Another good place to start is with a vacuum gauge. www.secondchancegarage.com has a great how to use / read a vacuum gauge section.
To answer a few questions.
Water in fuel - I don't think so. I always run the piss they call 91 octane out west here. But when I started to have this issue I put 10 gallons of 100 octane no lead with no change. I also added a can of Sea Foam. So probably unlikely, but I could pump the tank empty and put fresh fuel in.
Timing chain slop - I'm sure there is some as I didn't put a tensioner on it, but I used a Cloyes roller chain. I was thinking this might be why it was so out of phase. Hard to say, but there doesn't seem to be a lot of slop when turned by hand a few degrees each direction.
Coil - easy change. Might be able to borrow one to try.
Leak down/compression check- I don't have the tools for a leak down test, but I do have a compression gauge. That would be pretty easy and not a bad test to at least start with.
I think I will still pull the valve covers and change the pickup coil since I have a new one in the garage.
If anyone else has ideas I'm all ears!
Go ahead and change the PU coil but normally thats
a temp thing... it'll be working then quit then when
it cools it'll work again..but try it
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Re: Misfire/popping at Idle
[Re: urdustd]
#1601581
04/01/14 08:05 AM
04/01/14 08:05 AM
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Joined: Jun 2003
Posts: 3,325
Truckville, the capital of NY
85_Ram_4speed
master
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master
Joined: Jun 2003
Posts: 3,325
Truckville, the capital of NY
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I know when mine started popping at idle, I found a couple of holes that were way down on compression---not dead, but about 25-30% lower.
Also check the header gaskets too to see if one might not be sealing properly and sucking air in around it.
Outcast Dodge guy.
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Re: Misfire/popping at Idle
[Re: MR_P_BODY]
#1601582
04/01/14 08:05 AM
04/01/14 08:05 AM
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Joined: Dec 2004
Posts: 1,489
St. Louis Mo.
10 o to go
"Happy Don"
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"Happy Don"
Joined: Dec 2004
Posts: 1,489
St. Louis Mo.
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Im curious how did you relube the cam ?
Check for flat lobe slope in a rocker arm .
Plug wires moisture in wires from sitting .
Change spark plugs .
Few things that came to mind .
2009 418" build dan smith built
new 9.96 131.82
6.23 108
1.30 60 foot
best to date 9/15/09
8in 727 430 dana 2860 lb 3040 lb w driver
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Re: Misfire/popping at Idle
[Re: urdustd]
#1601583
04/01/14 10:06 AM
04/01/14 10:06 AM
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Joined: Jan 2003
Posts: 864
St Paul MN
73swinger
super stock
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super stock
Joined: Jan 2003
Posts: 864
St Paul MN
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Hi Jim. If you are running hydraulic cam, maybe check for a pumped up/stuck lifter. i had that issue, seemed to drive well, but idle would miss a bit. Also the exhaust made a pfft pfft kind of sound.
Good luck. keep us updated.
Chris Schwartz
73 Swinger 340 12.451 @ 108.78
73 Gold Duster, needs a plan.
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Re: Misfire/popping at Idle
[Re: urdustd]
#1601587
04/01/14 02:57 PM
04/01/14 02:57 PM
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Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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If its truely a miss then the exhaust really wouldnt do it BUT if its a popping sound then yes it can be the header loose.. so make sure what you have
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Re: Misfire/popping at Idle
[Re: Crizila]
#1601589
04/01/14 03:48 PM
04/01/14 03:48 PM
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Joined: Jan 2003
Posts: 660
River Falls, WI
urdustd
OP
mopar
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OP
mopar
Joined: Jan 2003
Posts: 660
River Falls, WI
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Quote:
Lots of good suggestions on this thread. Don't hopscotch. Take your trouble shooting one step at a time and try and start with the easiest stuff first. Often you will find that it is NOT the worst case scenario ( dead hole, flat cam, etc.) If your problem started right after you changed something, that is usually the first place to look. If nothing shows up and you have no clues, start with the mechanicals as they are often visual checks and easy to do. All good?, move over to the fuel stuff as it is usually the next easiest to trouble shoot. Lastly, electrical, as much of it is non-visual and some of it is non-testable. With a good trouble shooting procedure ( leaving nothing out ) you will find the problem. 
That is the plan and I do appreciate the input as somethings you just flat overlook as you get more frustrated.
I guess I want to reiterate. The condition appears to me as spark knock and that is why I went straight to the ignition system. As the rpm's climb the condition is much less noticeable (or disappears) and lead me to the phasing, timing, advance, and general ignition components.
I will put a list together from easiest to hardest and work my way through it. I'm sure I'll find it, just hoping it is not too bad as I have enough other junk I own to work on!
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Re: Misfire/popping at Idle
[Re: urdustd]
#1601590
04/01/14 04:07 PM
04/01/14 04:07 PM
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Joined: Oct 2003
Posts: 7,506
Az
Crizila
master
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master
Joined: Oct 2003
Posts: 7,506
Az
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Quote:
Quote:
Lots of good suggestions on this thread. Don't hopscotch. Take your trouble shooting one step at a time and try and start with the easiest stuff first. Often you will find that it is NOT the worst case scenario ( dead hole, flat cam, etc.) If your problem started right after you changed something, that is usually the first place to look. If nothing shows up and you have no clues, start with the mechanicals as they are often visual checks and easy to do. All good?, move over to the fuel stuff as it is usually the next easiest to trouble shoot. Lastly, electrical, as much of it is non-visual and some of it is non-testable. With a good trouble shooting procedure ( leaving nothing out ) you will find the problem.
That is the plan and I do appreciate the input as somethings you just flat overlook as you get more frustrated.
I guess I want to reiterate. The condition appears to me as spark knock and that is why I went straight to the ignition system. As the rpm's climb the condition is much less noticeable (or disappears) and lead me to the phasing, timing, advance, and general ignition components.
I will put a list together from easiest to hardest and work my way through it. I'm sure I'll find it, just hoping it is not too bad as I have enough other junk I own to work on!
 I hear that last part.
Fastest 300
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Re: Misfire/popping at Idle
[Re: Crizila]
#1601591
04/01/14 07:54 PM
04/01/14 07:54 PM
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Joined: Sep 2003
Posts: 2,008
Sweet Home Alabama
MRMOPAR622
top fuel
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top fuel
Joined: Sep 2003
Posts: 2,008
Sweet Home Alabama
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Check the lobes on your camshaft,I don't think it will be flat but wore bad.That will cause one to pop at idle but sound more clear off idle and it does not have to be wore all that bad.If you have roller lifters you may find the problem when checking the camshaft.
"To Be The Man'You Have Got To Beat The Man"
"T/D and Pro-Bracket Racer"
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