[RV9Otter]

Playing with my new RV9A today an issue popped up that was not there yesterday...the first day I've had it. Sorry if I don't have all of the helpful facts up front but here is what I experienced.

When I did the mag check on the left during run up, the RPM reading on the EFIS went to zero. I could tell that the RPM did drop the normal amount. When I shut off the right, the normal RPM drop showed on the EFIS. I checked to see if both left and right would shut the engine down, and both did so it is not a broken p-lead. I'm sorry but, I also have an electronic ignition and one mag, but, I don't know which is controlled by witch switch.

So, I believe that I have established that both ignition systems are functioning correctly, but, when I shut the left one down, the reading on the EFIS goes to zero, but the engine experiences the normal RPM drop.

Where does the EFIS get its RPM information and where should I start looking for a problem?

It almost seems like a lose connection because once or twice the RPM drop associated with shutting down the left switch showed a slight drop just before going to zero. Thanks, Curt

 

[Mike S]

Where does the EFIS get its RPM information and where should I start looking for a problem?

Thanks, Curt

Curt, first off---------Congrats on the new plane

The EIS can get its signal from a variety of sources--------only a couple ways to tell that I can think of----------one is to trace out the wiring, other is to go into the setup/configuration pages of the EIS---------this can cause strong men to tremble in fear----GRT documentation is notoriously difficult for non techies to deal with.

From what you are describing, I suspect you have only one of the ignitions supplying a signal to the EIS.

Best bet would be to talk to the person who built the plane.

 

[Ironflight]

I agree with Mike. most early GRT installations got the RPM from only one Mag, so when you check the mags, you get zero on one of them. Not a big deal really.

I have seen people try to discriminate whether the difference between the two mags is 50 or 75 rpm. What you're really looking for on a mag check is "reasonableness." You want to make sure that one mag isn't completely dead (the engine will quit when you're on it), or that you don't have a fouled plug. If you have a fouled plug, you'll know it from the extreme drop and roughness - not by a small RPM difference.

Paul (running a GRT with only one ignition sensed for 1800 hours now....)

 

[RV9Otter]

Gentlemen...You are all correct!

Gentlemen:

Heard from the prior owner/builder and you are correct, there is no RPM signal from the electronic ignition to the EFIS, only from the Mag. I don't know why I didn't notice this on prior ignition checks.

Thank you,

Curt

 

[jjconstant]

Actually there is a very good way to do the mag check without needing rpm. On your Horizon engine page, once you have stabilized at your run-up rpm, set your egts to "normalize". This will set them all to 0. Check your first mag and simply look to see that all egts are rising. Then switch to the other mag and again verify that they are all rising. This tells you that all the plugs are still firing and you don't have a cold or fouled plug. Engine roughness and/or "excessive" rpm drop (which is very ill defined) are all symptoms of a problem and lack of egt rise is also a symptom but it will also tell you WHICH cylinder, plug, mag or lead is the culprit.

 

[curtis]

I know with the GRT EIS 4000 manual, there is a page towards the back where all of the connector diagrams are located and it shows how to put a switch in the system to check both mags. I have installed this setup and it is fairly straight forward. When doing the mag check with the switch installed you just have one extra step to select which mag the GRT is getting its signal from.

 

[DanH]

Curt, you can easily connect your second ignition source to the EIS system, (which in turn feeds information to the EFIS via a single serial port wire).

The EIS has two tach input wires, #1 and #2. From the manual:

Two inputs are provided to allow sensing the engine RPM from either of two sources. The EIS will use tachometer input 1 when a tachometer signal is sensed. If tachometer input #1 is not providing any RPM indication, the EIS will use tachometer input #2. Each tachometer input has a corresponding TachP/R setting allowing them to be independently configured. This allows the use of two dissimilar tachometer inputs, such as a magneto and an electronic ignition input. The settings are identified as Tach1P/R and Tach2P/R, corresponding to each of the inputs.

Download GRT manuals at http://www.grtavionics.com/manualseis.html

 

[David-aviator]

Curt, you can easily connect your second ignition source to the EIS system, (which in turn feeds information to the EFIS via a single serial port wire).

The EIS has two tach input wires, #1 and #2. From the manual:

Two inputs are provided to allow sensing the engine RPM from either of two sources. The EIS will use tachometer input 1 when a tachometer signal is sensed. If tachometer input #1 is not providing any RPM indication, the EIS will use tachometer input #2. Each tachometer input has a corresponding TachP/R setting allowing them to be independently configured. This allows the use of two dissimilar tachometer inputs, such as a magneto and an electronic ignition input. The settings are identified as Tach1P/R and Tach2P/R, corresponding to each of the inputs.

Download GRT manuals at http://www.grtavionics.com/manualseis.html

This is how it works with EIS 4000 in my 8, but that feature is relatively new, older units did not have the soft ware to support it. In the 7, there was a switch to select which mag would feed EIS to observe the rpm drop.

But this 9 has electronic ignition on one side, I don't know how it will work. GRT would have the answer.

 

[tim2542]

Which electronic ignition?

If it's a Pmag you can convert the tach source from Mag to Pmag and it will drive the tach signal even when grounded during a mag check.
Also, the early EIS can be converted to dual tach source. If you feel you need it, send it to GRT for upgrade.
Tim Andres

 

[curtis]

Curt, you can easily connect your second ignition source to the EIS system, (which in turn feeds information to the EFIS via a single serial port wire).

The EIS has two tach input wires, #1 and #2. From the manual:

Two inputs are provided to allow sensing the engine RPM from either of two sources. The EIS will use tachometer input 1 when a tachometer signal is sensed. If tachometer input #1 is not providing any RPM indication, the EIS will use tachometer input #2. Each tachometer input has a corresponding TachP/R setting allowing them to be independently configured. This allows the use of two dissimilar tachometer inputs, such as a magneto and an electronic ignition input. The settings are identified as Tach1P/R and Tach2P/R, corresponding to each of the inputs.

Download GRT manuals at http://www.grtavionics.com/manualseis.html

Thanks Dan,

But the I downloaded the manual you linked and the connector diagram Figure 5a is different from the manual that came with my EIS 4000. In my original manual Pin 24 on my connector is labeled "N.C." not used and reserved for future growth.

Not sure if this option was available in my version, however if I was wiring my up right now I would set it up as you have stated. Right now I am content with my switch and do not want to do any wiring, rather put dead dinosaurs out the tailpipe.

 

[jclark]

Thanks Dan,

But the I downloaded the manual you linked and the connector diagram Figure 5a is different from the manual that came with my EIS 4000. In my original manual Pin 24 on my connector is labeled "N.C." not used and reserved for future growth.

Not sure if this option was available in my version, however if I was wiring my up right now I would set it up as you have stated. Right now I am content with my switch and do not want to do any wiring, rather put dead dinosaurs out the tailpipe.

If you send it in to get upgraded from the older EIS that you seem tohave, you will find that in fact it works just fine with Mag/Mag, Mag/EI (P-Mag), EI (brand x)/EI (brand y). I have successfully used all of the above.

James

 

[curtis]

I don't disagree that having it upgraded would be good, but it is just I don't think I can survive a week or two with it gone. I might forget how to fly.