ION-related IGN Comments & Coil Quest

garfield at pilgrimhouse.com garfield at pilgrimhouse.com
Sat May 30 06:48:54 GMT 1998


On Fri, 29 May 1998 22:25:16 -0700, eric schumacher
<e.schumacher at postoffice.worldnet.att.net> wrote:

>If all you guys want to do is measure the secondary current why not just use
>a current transformer strung on the HT lead.

NO, this is NOT what we're trying to do. Please ignore that!! It was a
mistake someone UNFAMILIAR with the project made. God, let's not now
have all kinds of suggestions on how we can remotely measure the
secondary spark current, PULLEEZE. That has NUTHING to do with ION. The
current we are trying to measure is the current that a low voltage
source can drive through the ionization remaining AFTER the spark has
passed, and is on the order of 1 microAmp @ 80V. No way an inductive
pickup on the HV lead is gonna pick that up outta the noise floor.
Please Drop this business about ION being simply "measuring secondary
current". That is totally misleading and a plain MISTAKE.

>On a second subject Bosch coils have a internal gap in parallel with the HT
>terminal to protect the coil in case of an open secodary. This has an
>interesting effect when the plug gap opens up wide due to age. The engine
>gets hard to start when cold but will not miss under any kind of load.
>Cause? with a cold plug it jumps inside the coil rather in the plug.

Then kiss them goodbye as coils you can use with ionization detection
through their secondaries, unless you're using the HV diode isolation
method, and essentially attaching ION directly to the plug itself, AFTER
the coil.

Gar




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