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Date: Mon, 6 Jul 2009 17:56:39 -0600
From: Bob White <bob@bob-white.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: Avoid reading .....
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On Mon, 6 Jul 2009 19:37:58 -0400
"Ed Anderson" <eanderson@carolina.rr.com> wrote:

> 
>  
> On Mon, 6 Jul 2009 16:04:37 -0400
> "Ed Anderson" <eanderson@carolina.rr.com> wrote:
> 
> 
> <snip>
> > Any time the EC2 is not grounding its' side of the injector (causing it
> > to inject)  there is 12+ Volts at the EC2 injector pin on the EC2 box -
> > Unless you have turned the disable switch for that pair of injectors
> > off (no voltage to injectors). Until the EC2 grounding pulse there is
> > no current flow and therefore no voltage drop across the injector.  So
> > if there is 12+ volts on one side then there is 12+ volts on both sides
> > including at the EC2 injector pin. Once the ground pulse is sent then
> > the voltage is dropped across the injectors and there is indeed near
> > zero volts on the EC2 pin.  
> > 
> > So I would think it would be easy for the EC2 to sense whether there is
> > 12 volts on that pin between injector pulses and if there is 12+ volts,
> > then the EC2 would know it is powered up.
> 
> Yes, that would work, so it's quite possible that the EC2 is keeping
> track of which injectors have power.  I take back the blanket statement
> that it isn't happening.  Sorry Steve.
> 
> <snip>
> > 
> > Ok, we are now below staging point cooking along on two primary injectors
> (I
> > know you disagree with this point, Bob, but bear with me) When you drop
> > below that staging point the EC2 automatically doubles the nominal pulse
> > duration because you have stopped using the 2 secondary injectors.
> > Normally you are using the two primary injectors below staging. So we
> still
> > have the same fuel flow below with 2 injectors that we had above staging
> > point with 4 injectors - so fuel flow both sides of the staging point is
> the
> > same (ideally). Engine runs fine.
> > 
> > 
> > Now, while below staging, you manually turn off the primary injectors by
> > turning off their disable switch.  This removes power from the primary
> > injectors and grounds the cold start circuit. But - wait, I postulate that
> > below staging the cold start circuit is already in effect (doubling the
> > pulse duration).  So there is no further doubling and the EC2 senses power
> > removed from the primary injectors, senses power is still there on the
> > secondary injectors and immediately starts firing the secondary injectors.
> > Engine Runs Fine.
> > 
> > NOW IF this theory is correct then turning on the cold start switch on the
> > PCM panel with only one pair of injectors operating below staging - should
> > do nothing regarding the pulse duration as its already double that that
> > nominally required for 4 injectors. Engine Runs Fine. 
> > 
> <snip>
> 
> OK, but Steve has already reported that if he turns on the cold start
> switch while at idle, the engine will run rich and die.  I'm pretty
> sure I've done the same thing.  If one set of injectors is turned
> off, then the engine will run fine.  I think the cold start doubling
> and the staging pulse modification (halving on the way up and doubling
> on the way down) are independent from each other.  At least I think I
> understand our differences and thats some progress.  :)  I've always
> assumed that the cold start switch on the PCM would always double fuel
> flow and  setting cold start when disabling a bank of injectors would
> always keep fuel flow the same (within limits).
> 
> Bob W.
> 
> 
> Ok, Bob, I agree, it does appear that the normal doubling of the pulse for
> the primary injectors below staging is independent of the cold start
> doubling.  That then would indicate that turning on the cold start switch on
> the PCM panel would indeed double the duration again - giving  you about
> twice the fuel flow you need.  The engine, particularly at low rpm, would
> tend to bog on that much fuel as Steve indicated.
> 
> Interestingly enough, however, it does appear that below staging that simply
> turning off one pair or the other does not induce the cold start doubling as
> it does above staging point.  Otherwise, when I turn off the primary disable
> switch it should engage the cold start function and cause too much fuel -
> but instead, the EC2 appears to simply  kick on the secondary injectors and
> things continue per normal.  So, It appears that below staging you must use
> the cold start switch on the PCM panel to induce the cold start doubling.
> 
> 
> 
> Ed
> 
Hi Ed,

The PCM cold start switch and the injector disable cold start switch are
both tied to the same pin, Pin 30 on the EC2.

Bob W.


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