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From: "Al Gietzen" <ALVentures@cox.net>
To: "'Rotary motors in aircraft'" <flyrotary@lancaironline.net>
Subject: RE: [FlyRotary] EC2 probe grounding.
Date: Thu, 17 May 2007 22:34:00 -0800
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My take on this is that the circuit and firmware in the EC2 is set up =
for a
specific sensor.  The early version used a 10K thermister, and the later
version, a 3K.  In putting in some other sensor than the one Tracy =
supplies,
you best have some input from Tracy.  If yours has about a 3K resistance =
at
ambient, it may be OK.

In the current version one side is connected to pin 1 (ground) and the =
other
to pin 31.  Early version connected pin 11 (+5v, I think) and pin 31.

I'm having some issues with mine right now, and it may be because I have =
a
10K sensor, and a newer replacement ECU.  You can connect a fixed =
resistor
in place of the sensor (probably a 3K Ohm in your case), and it will =
work
just fine until you are sure what you need.=20

Al


To: Rotary motors in aircraft
Subject: [FlyRotary] EC2 probe grounding.

Just pinging the group on this.

Chris (and every once in a while I) are to the stage of wiring up=20
goodies to the EC2. We have the injectors, resistors and most of that=20
stuff done. Next is the inlet air temp sensor for the EC2 (to be=20
followed by all the other sensors for the EM2).

There are two wires for the EC2 air temp sensor. There are conflicting=20
instructions and diagrams with regards to a new and old scheme that=20
involve 2 of 3 possible pins on the plug (I think it was 1, 11 and 31,=20
but not positive - you can look at the EC2 diagrams regarding this.

Anyways, the VDO air temp probe I am using is a 1/8" NPT 300 degree F=20
with a terminal on top that can receive a female spade connector.

The top terminal is clearly insulated from the rest of the probe, and=20
the body of the probe is the ground.

What is the best method for wiring this type of probe.. obviously one=20
wire to the top terminal, the positive if so designated. But do we put a =

ring terminal on the body of the probe and hook up the second EC2 wire=20
to it? Or do we consider the engine block the ground, which the intake=20
will be firmly attached to, and connect the second wire to our forest of =

tabs grounding block on the firewall.

It seems that grounding the probe with a ring terminal can introduce a=20
ground loop because now there are two potential paths back to the EC2.=20
Are the air temp leads electrically isolated (transformer coupled, for=20
instance) or is a ground loop possible.

More than anything else, I would like to hear from those of you who are=20
flying with the EC2, because at this point I need practical, not=20
theoretical help. I know Tracy is off the grid, so I may wait a while to =

hear from him, but the rest of you with EC2 rotary time, please tell me=20
how your set-up is set up.

Dave (and Chris)

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