capacitor for coil 12V pos supply ?

General Megajolt Questions and Answers

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EA82GT
Posts: 24
Joined: Sat Jun 12, 2021 11:01 pm

capacitor for coil 12V pos supply ?

Post by EA82GT »

OK, there is a youtube out there , soundless demo of the components, showing among other things, the pos and neg of the crank sensor and a part number.

Among the comments viewers have added, someone who has done 20 odd EDIS set ups, mentioned that on all Fords donating EDIS units use a 5 to 25uF capacitor in the positive power supply to the coil (s) what is the go here from ASL view on things ?

Same person says MUST use resistor HT leads and or resistor spark plugs.

OK, seen Brent ask us to use resistor spark plugs. Have got leads made for the Ford Crown Victoria 1996 so it was EDIS V8, so leads should be fine.

Can't say I know what "resistor leads " are anyway. I know I use low resistance leads on my LPG stuff

Brent ??

brentp
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Re: capacitor for coil 12V pos supply ?

Post by brentp »

We don't know anything about the capacitors. Yes, you need resistance spark plugs, otherwise you'll have a ton of EMI/RF interference, which could disrupt electronics on the car.
Brent Picasso
CEO and Founder, Autosport Labs
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EA82GT
Posts: 24
Joined: Sat Jun 12, 2021 11:01 pm

Re: capacitor for coil 12V pos supply ?

Post by EA82GT »

OK , curious , I should see if I can find the 'tube and the comment. Interesting to know you do not use a cap. and collectively would have done thousands I would guess. Lucky I don't have much in the way of electronics onboard. I did read of someone reverting to non resistor plugs to debug something. I must be getting close to reading too much before jumping into the job :) Thanks Brent

brentp
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Re: capacitor for coil 12V pos supply ?

Post by brentp »

* I think there are many installations without external capacitors.
* Use resistor plugs to start.
* Yes, you're overthinking it. :)
Brent Picasso
CEO and Founder, Autosport Labs
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EA82GT
Posts: 24
Joined: Sat Jun 12, 2021 11:01 pm

Re: capacitor for coil 12V pos supply ?

Post by EA82GT »

* the over-thinking ...it is genetic, from both sides of blood lines. Definitely no Gung Ho's in my DNA :)

laruetou2
Posts: 10
Joined: Sun Aug 15, 2021 4:05 pm

Re: capacitor for coil 12V pos supply ?

Post by laruetou2 »

I have the same question on the capacitor.

Based on comments that the capacitor wasn't need, I originally omitted this component. But, every wiring diagram that I've seen, including Megasquirt (Bowling & Grippo), show a 25uf capicator in the power circuit feeding the EDIS and coil. The Ford 2nd gen wasted spark coils have a capacitor fed by a green wire that disappears into the harness and is grounded to the engine.

So I've dug up the capacitor that had been set aside and I have gone back and added that to my application - maybe does nothing but complies with the wiring diagrams.
Larry

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