Suppressor on coil feed?

General Megajolt Questions and Answers

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Elf
Posts: 3
Joined: Sun Aug 08, 2010 7:53 am

Suppressor on coil feed?

Post by Elf »

I'm currently intalling my megajolt junior using a Ford EDIS4 and coil pack and remember reading somewhere that a 25 microfarad suppressor should be fitted on the 12V supply to the coil, but I don't see that mentioned in the fitting instructions I downloaded.
Is it a good idea to fit a suppressor in the 12v supply to the coil? I can only find a 2 microfarad suppressor locally. Will this be OK insetaed of a 25 microfarad suppressor?

DannyP
Posts: 417
Joined: Sun Apr 09, 2006 3:48 pm

Post by DannyP »

I don't think it is needed and a lot of people eliminate it. I did and don't have any issues, been running for over two years now.

BRUCEROE
Posts: 96
Joined: Wed Mar 03, 2010 10:00 pm

Post by BRUCEROE »

There were caps connected to the harness of my coil packs, from the factory. They are a lot less than 25 micro farad, about 0.24 mf on my bridge. The original mfg thought they were worth the cost, to avoid interference caused marginal operation of systems in the car. I don't want to be tracing bugs with a scope later, so I re use them. Bruce Roe

brentp
Site Admin
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Joined: Wed Jan 24, 2007 6:36 am

Post by brentp »

this comes up from time-time. It would be good to measure and publish the effects on the power supply rail with and without the filtering caps.

Speaking of interference- I had a good lesson of observing RF induced radiation superimposed all over my test bench and tested circuits (megajolt2). The plugs were acting like a very effective "spark gap transmitter, especially as they weren't plugged into an engine block. Solution was to short the coil pack terminals. Then, I was left with measuring interference on the supply rail only induced by the coil primaries discharging- which is what I was really looking for, anyway.
Brent Picasso
CEO and Founder, Autosport Labs
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Elf
Posts: 3
Joined: Sun Aug 08, 2010 7:53 am

Post by Elf »

Thanks for the comments guys. I guess since I've already got this 2 microfarad suppressor I may as well splice it into the 12v supply to the coil. From the comments it seems it can't do any harm.

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