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Date: Mon, 30 Aug 2004 13:03:07 -0400
From: Mike Robert <pmrobert@bellsouth.net>
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To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] EM2 - liquid emp 2 hookup
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Al Gietzen wrote:

> Rusty;
>
> The diagram you posted is correct; but, just discussed with Tracy and 
> understood that you should NOT use the voltage source (red lead) from 
> the OAT sender. I am going to pick up the +5v from Aux air 1 – he said 
> that should be fine.
>
> I will be doing the repair on the redrive myself – report later.
>
> BTW; further to the pulse filtering on the MAP, I realized that on the 
> dyno we had teed into the line between the port and the EC2 for the 
> line to the dyno MAP readout – which has an accumulator can in the 
> line. Which apparently explains we were able to get pretty good slow 
> speed running; once we got it leaned out enough. I’m thinking that the 
> best approach is like an R-C filter; some accumulator volume teed into 
> the line (dead end) - capacitor, and some restrictor orifice near the 
> EC2 connection - resistor. The question is the correct volume and 
> restrictor size. Don’t want to go too far and reduce the response time 
> too much. My guess is that a .040 restriction will have little effect; 
> maybe .015 - .020. The amount of flow in and out of the little sensor 
> with MAP changes is very small.
>
> Al
>
Al, been there, doing that with the RC thing - .04"/1mm and a cheap 
generic plastic fuel filter work very well at all RPM and load ranges. I 
can send you some datalogs if you wish. If the orifice is too small, the 
ECU has to wait a few tenths of a second for an accurate MAP signal. 
This causes a short period of enleanment and a momentary stumble. It's 
actually the flow in and out of the capacitance that you're restricting, 
not the extremely miniscule flow that the sensor diaphragm generates, if 
any. I think most MAP sensors are strain gauges. You want 
Manifold->R->C->MAP sensor as your sequence of parts. I've spent many 
hours getting this right by trial and error and have extremely smooth 
sensor response even at .01 second data logging intervals at 800 rpm idle.

-Mike