[Diy_efi] Ignition "ringing"

[Chris Ice]

Hey all...I'm trying to capture a clean ignition signal and have had 
trouble doing so.  Have had in two cases...digital recording for feeding 
homedyno (thru either induction clamp or voltage divider across the 
coil) and another as an rpm signal to my maf signal conditioner from 
coil negative.  In both cases the signal is very noisy, and I'm told I 
have "ringing" going on in the ignition.  The car runs fine tho, as does 
my dash tacho (very "old world" 1977 tach).

This is an '80s GM HEI style electronic ignition, so has the somewhat 
boomerang shaped ignitor module with a standard looking ignition coil 
and what appears to be a noise cap attached but doesn't appear to work. 
  Is on a Fiat/Lancia product in case you care. ;)

Any background information or suggestions afa. elminiating noise in the 
ignition circuit so I can get a clean signal?  Or just general 
information on where noise comes from?

Thanks!
Chris
-- 
Chris Ice                    "Laugh'a while you can, Monkey Boy."
http://www.trub.com/                               - Dr. Lizardo



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