Karl,
I have gone through 4 EIS CHT probes in 5 different aircraft. They are
a bit flimsy in my opinion. That unwanted opinion forwarded, I have
always found it wise to replace the CHT ring. Write to Sandy at Grand
Rapids and they may even send you one at a significant discount. The
VDO probe sensor (single wire) is Rotax proprietary (because of the
thread) and is swapped with any of the other VDO probes for testing.
The two wire probes (the CHT ring that is held in place by the VDO
sensor tight against the head) I believe is a type J thermocouple. As
the ring heats, the resistance in the probe changes (magic) and is read
by the magic box. If the ring shorts, it sends improper voltage back to
the EIS and the box is very unhappy.
I am confused at your pin 4 comment, as as that is Red CHT #5 from the
thermocouple. #19 on the other plug is your water temp sensor wire.
It is amazing what one bad voltage input will do to our magic black
boxes.
Hope I am not confusing you.
Bud
----- Original Message -----
From: Karl Heindl<mailto:kheindl@msn.com>
To: europa-list@matronics.com<mailto:europa-list@matronics.com>
Sent: Saturday, July 31, 2010 5:47 PM
Subject: Europa-List: EIS problem identified
Ian, Gary, Bud,
Ian was right about the sensors. I used the only consistently wrong
value of 10.0 volt with the engine not runnunig as a refernce to work
with.
I pulled my 24 pin connector apart, which disconnects all probes, and
the volt display was good at 12.5. So now I just had to identify which
wire was the culprit.
I used one jumper and connected one wire at a time, until I came to
the CHT, which is pin4 on the EIS side. To be 100% sure I cut the wire,
reconnected the plug and ran the engine. Everything looks good except
for the cht of course.
One more question: Is the faulty part most likely the VDO probe or the
two-stranded wire ? The two wires are crimped onto a ring-connector, and
are hence shorted. I don't really understand theprinciple, but are the
two wires necessary ? Where can I get a VDO probe quickly ? motorcycle
or car parts shop ?
The mind boggles at the software in this EIS unit. It scrambled all
important parameters. My battery move was purely coincidental.
I think our lives would be a lot more complicated if it wasn't for
this forum.
Thanks again for all your help.
Karl
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