Odd stumble
Guest
Joined: Jan 2011
Posts: 646
From: Durham, NC
Well, after 2 weeks and no problems, today that changed. I struggled to get the truck home. It fought me the whole way but I made it. It totally died in the shop and wouldn't restart. Then I noticed with the engine off and key in run, the tack was jumping around, and I noticed a arching sound from under the hood. I jumped out and tried to find it. It was coming from that area of the coil, rear left side. But stopped before I could find it. I suspect what ever was making that sound is the source of my problem. The the truck restarted and ran fine. I tapped all around and nothing happened. Any thoughts on what I should be checking here?
Thread Starter
Senior Member
Joined: Jan 2011
Posts: 459
From: Sheboygan WI
I plan to pull the coil off and inspect it tomorrow. Something is aching to ground and it's causing the tach needle to jump. I'm thinking there may be a crack. I may end up just replacing the coil.
Thread Starter
Senior Member
Joined: Jan 2011
Posts: 459
From: Sheboygan WI
I decided to replace the coil. I was driving back from the DVM and autozone was right there, so I stopped and picked one up.
I tested the secondaries on the new coil.
And tested the primaries.
Then I tested the primaries on the old coil.
And the secondaries on the old coil.
Hmm, wonder what is wrong?
I tested the secondaries on the new coil.
And tested the primaries.
Then I tested the primaries on the old coil.
And the secondaries on the old coil.
Hmm, wonder what is wrong?
Guest
Joined: Jan 2011
Posts: 646
From: Durham, NC
I decided to replace the coil. I was driving back from the DVM and autozone was right there, so I stopped and picked one up.
I tested the secondaries on the new coil.
And tested the primaries.
Then I tested the primaries on the old coil.
And the secondaries on the old coil.
Hmm, wonder what is wrong?
I tested the secondaries on the new coil.
And tested the primaries.
Then I tested the primaries on the old coil.
And the secondaries on the old coil.
Hmm, wonder what is wrong?
Looks like the secondary is open.
Does it run now?
Thread Starter
Senior Member
Joined: Jan 2011
Posts: 459
From: Sheboygan WI
Yes, but it was running before, not sure how it could run with the secondaries open. I tested it several times, even used a file to clean up the metal and make a good connection. I would expect a open to not run at all.
Guest
Joined: Jan 2011
Posts: 646
From: Durham, NC
The air gap where the secondary winding opened would act like another plug gap, similar to 2 plugs firing together in series, like Ford's EDIS. So it might run, but poorly due to reduced voltage to the plugs.
Thread Starter
Senior Member
Joined: Jan 2011
Posts: 459
From: Sheboygan WI
That's a possibility. Perhaps it had a very weak spark. Then from time to time dropped out all the way. All I can do now is drive the truck and see what happens. I thought for sure I found the problem being a loose plug on the fuel pump. Ran problem free for 2 weeks. Perhaps the arching I heard was inside the coil.
Thread Starter
Senior Member
Joined: Jan 2011
Posts: 459
From: Sheboygan WI
I tested the old coil wrong. I should have tested from tach terminal to the post. Testing that way I get about 7.70 ohms. When I heat the coil up it goes over 8.50 ohms. The new coil starts about the same place, 7,.70 ohms. When heated up I go to a bit under 8.10
Guest
Joined: Jan 2011
Posts: 646
From: Durham, NC
The old coil sounds ok. A difference of 400milliohms is well withing the tolerances on the secondary winding resistance.
Thread Starter
Senior Member
Joined: Jan 2011
Posts: 459
From: Sheboygan WI
Ya, hard to say. But I really can't figure out why the ignition is kicking out. Something in that area was arching. There are a few plugs in that area, but I don't see any problems there. Only high energy I see is the coil. There may still be a crack in the old coil, I just can't say. If I ever get a chance I may have to put the old coil back on and start it up at night. Then mist the coil and look for any flashing.
