[Diy_efi] Ion Sensing project

[Raymond Outlier]

I'm replying with my temporary Lycos account, because although I've send a copy of
this to DIY, my friend Steve will probly hold it up or toss it before it reaches there any
time soon.

Gar

On Fri, 5 Jul 2002 19:26:13 +0300 (EET DST), Ville Vartiovaara <vvartiov at cc.hut.fi> wrote:

>Uh, isn't this the one you posted me yesterday, Gar? If not a mistake, why
>not forward my answer too..? ;)

I did post this early yesterday Ville, but as I explained, had to send it to you direct
because the moderator was holding it up. I gather he finally got around to deciding
it was 'purely technical' and so acceptable for the PC. He holds up all my posts.
It's his form of 'personal moderation' just for me. Isn't that special? :)

Anyway, yes I'd be happy to post your most helpful answer; here tis:

On Thu, 4 Jul 2002 23:04:25 +0300 (EET DST), Ville Vartiovaara <vvartiov at cc.hut.fi> wrote:

>
>> In addition to the above, in your other recent post, you also remark
>> about the CDI systems being faster than the coil/inductive spark
>> systems. But you've said you have a conventional dizzy/coil arrangement.
>> How are these two facts reconciled?
>
>Poorly ;) The coil is lossy, and as I just mailed (privately) to another
>guy on the list, I haven't run to this point yet, as my engine is merely
>economical ;) 
>
>Actually I don't see a problem here, because as you write below, the spark
>can well be cut off somewhere nead TDC, when it starts to bother. Because
>as we 'see' how well the mixture is detonated, we can advance the spark so
>that we need no spark after that. That's what I'm going to add to my coil
>the first time I get to crashcourse with this. 
>
>
>> It would seem your standard inductive IGN violates this 'fast decay'
>> criterion. Unless you're overtly terminating the HV earlier than just
>> letting the coil decay normally. Have you actually *measured* the decay
>> time till the IGN pulse is passed the threshold of obscuring the ion
>> current. I grant you, you have a spark gap in the dizzy to help you, but
>> unless you have a very lossy coil, your spark durations at the plug are
>> still going to be WAY longer than any CDI single-spark system.
>
>Sure. The problem only arises when we get the spark last beyond TDC. Then
>it can be cut off. (On the primary side of course..;)
>
>
>> Just how clear and unobstructed a window do you really think you have to
>> the post-HV-ignition ionization period, when the trailing off of normal
>> inductive IGN is soo long?
>>
>
>At the load at which I can use my engine: clear enough (oscilloscope). For
>normal engines with a plain coil: see the proposal above ;)


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