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  #1  
Old 05-07-2004, 05:39 PM
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So I have a brand spanking new pigtail connector for hooking up the TFI coil. But it has two green wires on one side, and (of course) the one red wire on the other side.

So, all the wiring diagrams show a single green wire from the module to the coil...what is the other green wire on my connector for?

TIA - hoping to upgrade the wiring on the 76 from presto(crap) to TFI tomorrow...
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Old 05-07-2004, 05:56 PM
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Actually, I don't know. You should only have 2 wires on the TFI coil connector harness. I guess I would just cut the other green wire off. I have a MSD TFI coil harness and there are only 2 wires on it(purple and orange, color coded for the 6A, but it works for any application whether you have a 6A or not). It must be a factory style coil wire harness for some other application as I have never seen TFI connectors with 3 wires on them. Where did you get the connector from? What was it supposed to be for? Are you doing any other ignition mods besides the TFI coil?
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  #3  
Old 05-07-2004, 06:35 PM
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Tach lead.

Anthony
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  #4  
Old 05-08-2004, 04:14 AM
Alzamon Alzamon is offline
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When I did mine it came with 3 wires as well. 2 green and the red. I just cut the extra one off.
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Old 05-08-2004, 04:16 AM
krejr krejr is offline
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I thought somebody once said that the other green wire was used for the resister? If not, where does the resister hook up then?
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  #6  
Old 05-08-2004, 05:09 AM
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Quote:
Originally posted by 89grand:
Are you doing any other ignition mods besides the TFI coil?
Umm - yeah... I have to swap the entire igniotion system from the presto lite module and dist. to the duraspark klind, then I am installing the new 8mm spiral wires, coil, cap, rotor, adaptor, etc.

From what I've seen, tach lead seems like the right answer here.

Quote:
Originally posted by krejr:
I thought somebody once said that the other green wire was used for the resister? If not, where does the resister hook up then?
The resistor is on the other side of the circuit - in the side of the red wire. In between the ignition and the coil.
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  #7  
Old 05-08-2004, 06:52 PM
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http://fsjeep.homestead.com/TFI_Upgade.html

this guy hooked the extra green line up to the resistor.

I haven't done the upgrade yet, sorry.

C
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  #8  
Old 05-09-2004, 01:10 AM
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I hooked mine to the resistor too. I guess it's supposed to help with interference with the stereo. I don't know if it makes a difference or not. It was there, so I hooked it up. If you don't have a resistor, I would cut it.
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  #9  
Old 05-09-2004, 02:23 AM
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Quote:
Originally posted by cwisnoski:
http://fsjeep.homestead.com/TFI_Upgade.html

this guy hooked the extra green line up to the resistor.

I haven't done the upgrade yet, sorry.

C
Yeah, he did...here is the pic...
I wonder why? I am no electrician by any means, but how does a resistor at the end of a single wire do anything? I thought resistors were supposed to go in-line and lower the voltage??? What could one at the end off the line be for?

BTW, as a side note, I now have the TFI installed and the second green wire is currently doing nothing (taped off and hanging there for future use)
However, it is looking like (in my case) the full 12 V to the module is too much. My module heats up to "very warm" within about 5-10 minutes of running at idle.
So I think I am going to buy the resistance wires (P\N ECHLIN ICR22 or something comparable) and stick it inline between the module and the 12V source. Hopefully that will solve the overheating module thing.

[ May 09, 2004, 08:25 AM: Message edited by: jode ]
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Old 05-09-2004, 02:52 AM
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that is a capacitor not a resistor
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  #11  
Old 05-09-2004, 02:59 AM
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That explains a lot...

...so...what is a capacitor, what is it for, and what is it doing in this application?
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  #12  
Old 05-09-2004, 07:56 AM
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Quote:
Originally posted by Rogue:
that is a capacitor not a resistor
oh...right, right, right
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  #13  
Old 05-09-2004, 08:09 AM
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Capacitor (Condenser) - The capacitor performs several functions. It prevents the points from arcing and prevents coil insulation breakdown by limiting the rate of voltage rise at the points. It's primary function is to provide for a rapid decay of the primary coil current. The capacitor also "third-harmonic" tunes the coil, raising the peak output voltage and increasing the secondary voltage rise time. This increases the efficiency and the amount of energy transferred to the spark plugs. If the coil secondary voltage rises too quickly, excessive high frequency energy is produced. This energy is then lost into the air-waves by electro-magnetic radiation from the ignition wiring instead of going to the spark plugs where we would like it to go. Voltage rise time should be more than 10 microseconds; a 50-microsecond rise time is OK. Conventional systems have a typical rise time of about 100 microseconds.
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  #14  
Old 05-09-2004, 03:20 PM
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Still hard for me to understand...
I am probably oversimplifying things, but I usually tend to think of electrical current as more like a water current where things at the ends of dead-end lines will have no affect on the overall flow.
So how does a capacitor at the end of the line control voltage spikes?

Also, I am having that overheating module problem - I just checked the three TFI shcematics that I have and two of them show the resistor in line between the coil and (+) and one of them shows it in line between the module and (+). So which is it? In my application, it seems that since the module is overheating, I should stick it between the module and (+), but I don't really know what I am doing here since I had to totally redo the wiring...I have read alot of people saying that the coil itself could easily handle the extra few volts, but I know the modules are sensitive, and I need to know if they are supposed to be run on a full 12V if I can stick that resistor in there to bring the voltage down for the module?
Help?
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  #15  
Old 05-10-2004, 12:15 AM
Al Johnson Al Johnson is offline
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You might think of this application of a capacitor as bing similar to a water hammer chamber in your plumbing. It doesn't do much during regular flow, but helps smooth out the sudden changes.
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  #16  
Old 05-10-2004, 01:38 AM
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Thanks Al that helps.

BTT for:
Quote:
Originally posted by jode:
I am having that overheating module problem - I just checked the three TFI shcematics that I have and two of them show the resistor in line between the coil and (+) and one of them shows it in line between the module and (+). So which is it? In my application, it seems that since the module is overheating, I should stick it between the module and (+), but I don't really know what I am doing here since I had to totally redo the wiring...I have read alot of people saying that the coil itself could easily handle the extra few volts, but I know the modules are sensitive, and I need to know if they are supposed to be run on a full 12V if I can stick that resistor in there to bring the voltage down for the module?
Help?
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  #17  
Old 05-10-2004, 07:28 AM
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ANyone got a PN for that capacitor

Also, this just came up...do ignition modules have a grounding wire in the stock/OEM configuration?

My module is currently not grounded very good - could that be the problem?
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  #18  
Old 05-10-2004, 08:28 AM
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Is anyone running full voltage to the coil lately? I read that the TFI coil can take a full 12v, but I don't know about alternator 14v. Right now I'm running stock resistor voltage to both, but I could see the benefit of full 12v. Is anyone running some sort of regulator or resistor to limit the voltage to 12v max??
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  #19  
Old 05-10-2004, 01:13 PM
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I got the TFI kit from the www.driveajeep.com folks (I'm lazy). Their instructions said to cut off the second green wire.
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  #20  
Old 05-10-2004, 02:40 PM
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I just finished converting my Prestolite system to Duraspark TFI. I put in a resistor on the line going to my module, but let the full 12V go to the coil. I tapped both of these from the "L" splice located under the dash, consisting of four red wires in an X configuration. I started it up today and it works FANTASTIC. I haven't driven it around yet though.

The guy to ask about all that is Lindel. He apparently researched it and determined that it was okay for 12V to go to the coil. He said that only giving the coil 6-8V was a carry over from a previous design with the can-type coil, and Ford being Ford didn't bother to research whether it would be better to give it 12 since they knew 8 would work.

As to your question about grounding the module, from what I understand the only ground that it has is the black wire going to the distributor, which grounds through the distributor. People recommend splicing in an extra wire to that black wire and grounding it.
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