I am awaiting a call from the folks at Grand Rapids. Greg T was out at lunch
when I rang.
Thanks for your comments John, I also noticed the rise in temperature as the
unit heats up. This seems to be the only reading that I get on the EGT/CHT
displays. When the unit is switched on it starts at about 15C and then
gradually rises to about 25C. I didnt realise what this was till you
mentioned it. Unfortunately, taking a blowtorch to the EGT probes has no
effect whatsoever on the display. It is as though something inside the unit
is disconnected.
I am hoping there is a simple fix but I am getting a feeling it may be more
serious.
----- Original Message -----
From: <JohnJMoran@aol.com>
Subject: Re: Grand Rapids EIS problem !
> Hi Carl,
>
> I am also using the EIS and have found it to be an excellent instrument.
>
> You didn't say whether you had checked the software setup of the
instrument
> to ensure that it is configured to have two EGT's and two CHT's -- this
would
> be a good thing to check prior to calling GRT.
>
> I called GRT a couple of times and they were very helpful. One thing
about
> the unit which is not obvious is that the temperatures displayed won't go
> below the unit temperature because the unit temperature is apparently used
to
> compensate the thermocouple junction. A side effect of this is that in
> testing the unit with the engine off in the shop, the displayed
temperatures
> will slowly rise to 25F or so above ambient due to self-heating of the
unit.
> Another side effect: the EIS unit temperature is useful in determining the
> temperature behind the panel (after subtracting 25F) to decide whether the
> panel airflow is sufficient to cool the radios -- the EIS can likely take
the
> heat due to its robustness and simplicity.
>
> Like you, I fitted the fuel pressure transducer which works well and is a
> source of comfort with all the talk of blocked filters.
>
> In wiring, I ran a separate ground wire to the engine block directly from
the
> EIS rather than using the single point ground plate I placed on the
firewall
> (this ground plate connects to the engine block via a #10 wire) which was
> used for everything else. Don't know whether the separate EIS ground was
> helpful, but the EIS readings are all very stable with this setup.
>
> Regards, John N44EU
>
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