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Dave,
I am not flying, but the following is considered practical. A thermistor
does not have a linear output per temperature. The curve is is a 3rd
order equation (typically Steinhart-Hart equation) which the receiving
device has to interpret. What that means is if you use a thermistor that
does not match any one of the 3 thermistor constants, the EC2 program will
not accurately convert the electrical signal to temperature. To avoid
data errors and problems, I would encourage you to use the thermistor that
was supplied with the EC2.
Joe
On Fri, May 18, 2007 1:06 am, David Staten wrote:
Just pinging the group on this.
Chris (and every once in a while I) are to the stage of wiring up
goodies to the EC2. We have the injectors, resistors and most of that stuff
done. Next is the inlet air temp sensor for the EC2 (to be followed by all
the other sensors for the EM2).
There are two wires for the EC2 air temp sensor. There are conflicting
instructions and diagrams with regards to a new and old scheme that involve
2 of 3 possible pins on the plug (I think it was 1, 11 and 31,
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
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
the body of the probe is the ground.
What is the best method for wiring this type of probe.. obviously one
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 to
it? Or do we consider the engine block the ground, which the intake 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
ground loop because now there are two potential paths back to the EC2. Are
the air temp leads electrically isolated (transformer coupled, for
instance) or is a ground loop possible.
More than anything else, I would like to hear from those of you who are
flying with the EC2, because at this point I need practical, not
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
how your set-up is set up.
Dave (and Chris)
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