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post #1 of (permalink) Old 12-02-2000, 07:03 PM
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TFI Ground Question

Hey Guys,

I just talked to a friend of mine and he mentioned that my TFI wasnt grounded correctly. I am curious what yall are doing to ground your coils? The square metal part is supposed to have a nice ground on it right? I am thinking to the block?

Thanks

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post #2 of (permalink) Old 12-03-2000, 08:14 AM
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Re: TFI Ground Question

repost


anyone?

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post #3 of (permalink) Old 12-03-2000, 09:16 AM
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Re: TFI Ground Question

I have the parts, just haven't done it yet. If the engine runs good, then the coils wiring must be good. If you have RFI....radio frequency interference, then the mounting bracket that the frame of the coil bolts to needs to be grounded to any metal of the body(steel) and/or the engine. My $0.02.

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post #4 of (permalink) Old 12-03-2000, 07:28 PM
 
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Re: TFI Ground Question

The 4-wire loom coming off the ignition module has a connector (I think its off the green wire?) that grounds the ignition coil. The other 3 connectors match up with the wires coming off the distributor. This is off my 1980 ignition

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post #5 of (permalink) Old 12-03-2000, 07:34 PM
 
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Re: TFI Ground Question

The ignition coil does not 'HAVE' to be grounded.
If it is grounded, or next to the 'Ground Plane' (Large chunk of metal, like the engine block) it will not do dastardly things to your radio or computer equipment via the transmission of Electro-Magnetic interference (EM Noise).
OR...
If the high voltage side of the ignition system has a defect, you will find Radio Frequency interference (RF Noise).

If you flip your radio on, especially on the AM (Amplitude Modulation) band, and you hear your ignition, then you probably have a coil wire, cap, rotor, plug wire or plug problem.

Try a spot of dielectric grease on the rotor nose, and a little touch on each of the cap terminals and see if the noise stops...
If not, get a new cap and rotor WITH BRASS TERMINALS, and try a little dielectric grease on them when you install them.
(Everyone is amazed with that grease on the rotor nose trick!!)
As the ignition fires, it oxidizes the metal in the cap and rotor, and creates resistance.
A little grease helps keep the free arcing to a minimum, and greatly dissipates the noise source.

Connecting a Capacitor to the positive side of the ignition coil will help with ignition noise also.
---------------------

The two basic types of ignition noise that appear in automotive electronics are easy to understand.

EM noise is the created by the forming and collapsing of the magnetic field inside the ignition coil.
A sheet metal shield (metal beer cans are always stylish!) over the ignition coil will block the EM noise for most sensitive equipment...

RF noise is created when large voltages try to get through a restriction.
Cheap plug wires, bad plugs, corroded or charred cap connections...
The noise created skyrockets when there is an air gap, like a break or loose connection in the coil or spark plug wires...

These are easy to diagnose with a cheap radio/ tape player....
Turn the radio on AM, and find a spot where there is no station.
Rev the engine, and see if you can hear the ignition in the radio.

If you can, then put in a tape with nothing recorded on it, or find a tape with a long silent spot at the end.
Switch over to the tape player, and see if you can still hear the ignition in the speakers.
---------------------

If you can hear the ignition in the radio, and not the tape player, then the noise is RF or EM, and can usually be traced back to the ignition or the alternator.

If you can hear the 'ignition' while the tape player is on, then it's not RF or EM at all.
It's probably power interruption noise from something like an ignition module, ignition coil, or alternator. (Heavy Power Switching Noise, not high voltage noise)
It's not your Plug wires or distributor cap.

High voltage switching noise by taking your radio off the same line as the component making the noise...
And by using a capacitor on the power side of both components.

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post #6 of (permalink) Old 12-03-2000, 09:08 PM
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Re: TFI Ground Question-Related Question

Well I finally got around to installing all the parts I collected for the TR/TFI Upgrade and, of course, it doesn't work. I have a '77 CJ-7 w/304 so I had to upgrade the dist to the motorcraft (which I did). Now that it all wired up it doesn't start. It'll crank but won't start. There is juice up to the coil but I can't tell where the problem is from there. It got too cold to keep messing with it tonight so I couldn't troubleshoot it any more so I thought I'd check with you all for any ideas on where to check next. Thanks for any and all info.
Oh yeah, I do have the older prestolite alternator w/external voltage regulator so the wiring was a little more confusing. I am not great with electrical stuff and my harness is already a mess so this could take a while. I plan to replace the entire harness when I do the frame off.
fratt
77cj7304QtracTH400
"in the middle of the TFI upgrade"

rich
77cj7304QtracTH400
79cj7frame,ready to be built
83cj7inpieces
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post #7 of (permalink) Old 12-05-2000, 12:31 AM
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Re: TFI Ground Question-Related Question

The rotor pointing to the right cyclinder? WHen you replaced the wires (not saying your stupid) did u get the exact order? If not it might fire but die.. try that

<font color=blue> Muddynut</font color=blue>
<font color=red>[img]/wwwthreads_images/icons/cool.gif[/img]'78 CJ7 "Issues"-304-35s</font color=red>[img]/wwwthreads_images/icons/cool.gif[/img]
post #8 of (permalink) Old 12-05-2000, 06:46 AM
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Re: TFI Ground Question

thanks for the replys guys. i think it must be my carb.

i dont seem to be getting the replys in my email for some weird reason

huh?

thanks again

[b]Boston Mangler
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