Does the ignition coil need to be grounded? - Ford Bronco Forum
 
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post #1 of 9 (permalink) Old 01-05-2009, 06:14 PM Thread Starter
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Does the ignition coil need to be grounded?

My ignition coil bracket is missing the rod that holds up the bracket and bolts into the eng block,is that a grounding point for the coil?

Also if that is what kind of problems would occur because of that?

92 Bronco, 351 Motor.
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post #2 of 9 (permalink) Old 01-05-2009, 06:26 PM
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I'm pretty sure that the bracket grounds the coil. Ergo if your coil is not grounded then it won't work and your truck won't run.

But the good news is that if she won't run you will be getting fantastic gas mileage......

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post #3 of 9 (permalink) Old 01-05-2009, 07:18 PM
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Doesn't matter. The iron core is there only to intensify the electromagnetic field created by the coil's induction properties and geometry. The (+) side needs battery voltage, the (-) side is switched on and off by the ignition module, and the secondary post is "grounded" when the coil fires, if you want to look at it that way.
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post #4 of 9 (permalink) Old 01-05-2009, 09:45 PM
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post #5 of 9 (permalink) Old 01-06-2009, 05:45 AM
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Originally Posted by SigEpBlue View Post
Doesn't matter. The iron core is there only to intensify the electromagnetic field created by the coil's induction properties and geometry. The (+) side needs battery voltage, the (-) side is switched on and off by the ignition module, and the secondary post is "grounded" when the coil fires, if you want to look at it that way.
almost...
The ignition module is typically open. It grounds the (-) side to build the spark. Then when it opens the circuit the spark is discharged. The longer the dwell time the greater the spark energy. The exact time the ignition module releases ground is the timing advance.
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post #6 of 9 (permalink) Old 01-06-2009, 01:11 PM
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I was trying to keep it simple!

But yes. Mostly. Greater dwell can only be effective to a certain point.

That was the premise behind CCD: only switch the coil current on long enough to make the electromagnetic collapse, when the primary circuit is opened, induce an adequate secondary voltage. This helps coil life by keeping primary current duration lower, thus dissipating less heat. It also theoretically allows better control, since the CCD TFI module will only fire when told to by the PCM, and the PCM can monitor whether its exact commands have been executed via IDM directly from the ignition module. Before CCD, the TFI was in control of dwell, and you would get a certain lag due to the filtering effects of the IDM circuit sourcing right off the ignition coil. This was more of a 'problem' at higher RPMs. Not terribly noticeable, but it was there.

Anyhow, when the field collapses, the secondary circuit is completed when the gaps are ionized and current flow begins. The (+) of the secondary circuit is the coil's output post, and its (-) is the vehicle chassis. I think that's what I was getting at.

EDIT -- I found a neat little Java-based example on this webpage: http://www.magnet.fsu.edu/education/...oil/index.html

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post #7 of 9 (permalink) Old 01-06-2009, 04:21 PM
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Originally Posted by SigEpBlue View Post
I found a neat little Java-based example on this webpage: http://www.magnet.fsu.edu/education/...oil/index.html
very cool

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post #8 of 9 (permalink) Old 01-06-2009, 08:38 PM
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Originally Posted by Fireguy50 View Post
The longer the dwell time the greater the spark energy.
...within the limits of the coil's design & the resistance of the 2ndry circuit.
Quote:
Originally Posted by Fireguy50 View Post
The exact time the ignition module releases ground is the timing advance.
...provided it occurs while the rotor is close to a cap terminal.
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Originally Posted by SigEpBlue View Post
...the coil current on long enough to make the electromagnetic collapse...
I think you mean "form".
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post #9 of 9 (permalink) Old 01-06-2009, 11:16 PM
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Quote:
Originally Posted by Steve83 View Post
I think you mean "form".
In the sentence I posted, "form" would've been the correct word. I guess my brain was ahead of my fingers again. The words between the commas should've been deleted, and the rest of the sentence should've been rearranged. I meant to say:

Quote:
Originally Posted by SigEpBlue View Post
That was the premise behind CCD: switch the coil current on just long enough so when the coil is switched off, the collapsing electromagnetic field will induce an adequate secondary voltage.
The underlined words would've added some clarity, no? In more simple terms, the coil primary should be on just long enough.

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