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  #16  
Old January 3rd, 2018, 11:20
trippled trippled is online now
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Re: Engine misfiring. Video inside. Any ideas?

Moved the o2 harness. That's a good spot to start. Or just disconnect it and go drive it and see if there's any change.
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  #17  
Old January 3rd, 2018, 22:28
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8Mud 8Mud is offline
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Re: Engine misfiring. Video inside. Any ideas?

If you have a tiny head gasket leak it can cause a miss after the engine warms up and the cooling system builds pressure.

Try removing the radiator cap running it for awhile and see if the miss disappears or gets noticeably better. You might also look for any bubbles in the coolant. A quick test is right after you start up hold a white paper towel under the exhaust and catch the drips. The coolant turns to steam in the cylinder and condenses some in the exhaust. It can drip out the exhaust after a cold start and the drips may show a tint the same color as your coolant. Head gasket leaks can be tricky to troubleshoot, it depends on the amount of the leak. Another sign is having to periodically add coolant, either a tiny plumbing leak or maybe a head gasket leak. When you run it with the radiator cap off you are likely to get some overflow, I usually wad up a rag and stuff it under the overflow, it will catch most of it, then rinse the whole area down with water after you're done-

You can also check your plugs for deposits and look down the spark plug hole at the top of the piston, too clean and it may be from the steam blasting off the carbon on the piston top.

My tips are a long shot, but heck you've already hit the more common causes.

Last edited by 8Mud; January 3rd, 2018 at 22:32.
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  #18  
Old January 6th, 2018, 13:23
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Ecomike Ecomike is offline
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Re: Engine misfiring. Video inside. Any ideas?

I would certainly use a volt meter under the hood to see if the voltage (Alternator, VRegulator, or battery wires or grounds have an issue)

But My most recent problem has me thinking the distributor may need indexing or replacing....and indexing. More on that later.... Is this rig new to you, or has it been running great for a long time in your possession???

Now ignoring the Dizzy possibility, my first thought is a clogged exhaust, busted up or clogged CAT converter????

Or a lack of fuel supply at pressure?

Is the fuel pressure holding OK as you hit the rpm limit??? Did you test that????

Make sure there is not a dead rat or snake in the air filter box, blocking air flow, LOL

So too little fuel flow, or air flow blocked, or a timing problem (distributor indexing)
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  #19  
Old January 6th, 2018, 13:32
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Re: Engine misfiring. Video inside. Any ideas?

Quote:
Originally Posted by cjomanche View Post
When I first got the truck it seemingly ran fine. I didn't notice anything "off" until at least a month after I bought it. I was coming back from a couple hour trip and I noticed one or two misfires on my way back while in 4th gear. I thought it was a fluke so I ignored it. Later on I discovered I could replicate this if I kept the RPMs around 2800-3000 for a little while. As long as I stayed out of that RPM range, I was fine. No issues to speak of.

A couple months ago, I changed the oil pan gasket, timing chain, oil adapter gaskets, clutch master cylinder, and front main seal. Immediately after this the misfiring problem got a lot worse, to where it is now.

What could have made it suddenly get worse in those repairs? Or could this problem have gotten worse on its own?
You have a timing problem!!!!! This is for sure!!!!! You need to redo the timing chain, and then index the distributor, and first make sure there is no play in the distributor shaft side to side or irrationally.

Mine had a shear pin that holds the cam gear on the Dizzy shaft going bad and it would move, slop around.....Then even the new Dizzy had to be indexed to get it in the sweep spot (Factory Cam shaft OEM errors) etc...

You could try replacing and indexing a new Dizzy or just indexing the old Dizzy first and see if that is good enough. If it was the original problem, the new timing chain may have made it worse (removed the slop that took it from marginal to worse).

But make sure there is no rotational slop or side to side play in the dizzy shaft. If there is, scrap it!!!

Once the dizzy is know to be OK and indexed, if there is still an issue I'd say the crank to Cam shaft timing must be off, maybe one tooth?
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Quote=8Mud: "Go ahead and put up the best fence you can build, I'll bet on some Mexican with a few dollars of nails and a pile of scrap lumber."
34 MPG , '85 2WD Cherokee Pioneer with custom installed, 64 hp, 2.2 L Nissan SD22 Diesel 5 spd Manual; & 4 Renix XJs, '87 Wagoneer 4.0, 4WD, 89-Cherokee, 4WD, '87 Cherokee 2WD, & '89 Cherokee Pioneer 2WD, all 4dr. #2091

Last edited by Ecomike; January 6th, 2018 at 13:39.
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  #20  
Old January 6th, 2018, 18:58
liamthered liamthered is offline
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Re: Engine misfiring. Video inside. Any ideas?

If, as you said, the lights dim when the issue occurs, I would start by checking the grounds. These things are well-known for ground issues if disturbed.
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  #21  
Old January 6th, 2018, 21:10
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blu3fan blu3fan is offline
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Re: Engine misfiring. Video inside. Any ideas?

Sir.
I had the exact same issue.
only mine only did it in gear.
dimming lights and everything.

I can honestly tell you I do not know what fixed it.
Was either bad o2 or bad cps. it could have also been the fuel ballast.
I messed with all of these one day.
2 years later now no issues.

My suspect is that it was the ballast


Mine happened after full engine rebuild.
I dont have the video. I looked.
did it for 2 months before I cured it.

make yourself an inline fuel pressure gauge. its the best $30 I ever spent on the jeep. That will tell you if its the ballast.

Last edited by blu3fan; January 6th, 2018 at 21:17.
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  #22  
Old January 6th, 2018, 21:14
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blu3fan blu3fan is offline
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Re: Engine misfiring. Video inside. Any ideas?

http://naxja.org/forum/showthread.php?t=1125531
theres my post.
hope that helps.
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  #23  
Old January 7th, 2018, 09:50
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Re: Engine misfiring. Video inside. Any ideas?

I think his is a 91-? Not sure they had the ballast anymore?
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Quote=8Mud: "Go ahead and put up the best fence you can build, I'll bet on some Mexican with a few dollars of nails and a pile of scrap lumber."
34 MPG , '85 2WD Cherokee Pioneer with custom installed, 64 hp, 2.2 L Nissan SD22 Diesel 5 spd Manual; & 4 Renix XJs, '87 Wagoneer 4.0, 4WD, 89-Cherokee, 4WD, '87 Cherokee 2WD, & '89 Cherokee Pioneer 2WD, all 4dr. #2091
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  #24  
Old January 7th, 2018, 17:01
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Re: Engine misfiring. Video inside. Any ideas?

AS the engine warms up the computer changes the spark timing, so that takes us back the Distributor indexing and the timing gear replacement!!!

Here is the how to index and HO engine write up link

http://www.angelfire.com/my/fan/dist_index.html

Quote:
Originally Posted by cjomanche View Post
But wouldn't this be the case even when the engine is cold? Immediately after starting the truck I can run the RPMs up as high as I want and there is no misfiring at all. As the engine starts getting warm it progressively gets worse over time. If the valve wasn't closing because of carbon buildup I don't see how heat would make a difference.
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Quote=8Mud: "Go ahead and put up the best fence you can build, I'll bet on some Mexican with a few dollars of nails and a pile of scrap lumber."
34 MPG , '85 2WD Cherokee Pioneer with custom installed, 64 hp, 2.2 L Nissan SD22 Diesel 5 spd Manual; & 4 Renix XJs, '87 Wagoneer 4.0, 4WD, 89-Cherokee, 4WD, '87 Cherokee 2WD, & '89 Cherokee Pioneer 2WD, all 4dr. #2091
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