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Date: Fri, 14 Sep 2007 21:00:51 -0400
From: cbeazley <cbeazley@innovista.net>
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To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: Re:  One for the smart guys
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>
> OK guys, here's one to think about. 
>  
> Problem:  Major mis-fire at 6600 - 7000 rpm.  Engine runs great up 
> until it begins mis-firing.  This is a 20B running an EC-2 that's been 
> updated with the latest s/w (as of 9/1/07).  This includes the snubber 
> fix and a modification for the Renesis CAS.  Before the snubber 
> upgrade, the engine ran good in the upper rpm range, but not in the 
> lower rpm range.  After the snubber upgrade & Renesis CAS 
> modification, it ran great in the lower rpm range, but had a 
> serious mis-fire beginning around 3800 rpm.  An attempt was made to 
> correct the mis-firing problem by installing a resistor/zener diode 
> circuit in the CAS lead (this strategy worked for another Renesis 
> flyer).  This approach was partially successful, but only up to the 
> mid 6K range. 
>  
> Multiple phone calls to Tracy resulted in no fix.  I think he's hiding 
> in Colorado so he won't have to take my calls. (I'm kidding, of course.) 
>  
> Finally, today (after months of struggling) I discovered what was 
> causing the problem.  It now runs great up to 7300 rpm, verified by a 
> full-power run down the runway.  Anyone want to guess as to what the 
> problem turned out to be? 
>  
> Mark S.

CAS shielding/grounding?