jbDC9

jbDC9

Well Known Member
Uh oh, a glitch.

I'm working on a -8QB, O-360-A1D with an E/Pmag combo with a GRT EIS 4000 engine monitor.

Did the first start today (much rejoicing, yeaa) and the tachometer read 0, zilch, nada. The Emag manual says the factory default tach output is 2 pulses per revolution, so I had previously set the Configuration Set (TachP/R) page on the EIS to 2. The wiring seems straightforward enough, yellow wire from the EIS to the #6 hole on the Emag control plug. The Emag manual also mentions the ability to change the output to 1 pulse per rev, but doesn't mention how to do it.

Weird. Has anyone seen this before? I'm going to call both GRT and Emag on Monday and see what they might have to say, but thought I'd check and see if anyone here has any ideas.

Thanks!
John Bixby
 
John:

My pmag equipped O360 should be shipping next week and I was reading about the tach interface last night. Emgair has updated their documentation and reference their new EICAD utility that will allow you to change the timing and change the tach signal...

From: http://www.emagair.com/Manual L113v25.pdf

"Tach Output - Tach output can be set to either one or two pulses per revolution to match your digital tach instrument. Factory default is two pulses per revolution.

Builders with Model 113 R3 or later can use EICAD to raise or lower the voltage of the E-MAG tack signal. Some instruments are designed to get a signal from a magneto p-lead (higher voltage) while others are designed to use a probe in the side of the magneto (lower voltage). The factory default is for a low voltage signal."

Good luck.

Mike Draper
RV-8
finish
 
I haven't messed with a pmag John, so I can't help you much therer - although to me, it doesn't sound like a software setting - I'd think you'd get SOMETHING, even though it's wrong.....

but hey, CONGRATULATIONS on the engine start!!!

Paul
 
I believe that you need to call GRT. The Emag tach pulse is low voltage (5v IIRC), the EIS is expecting to see a mag pulse of ~ 300v. I think the basic problem is that the Emag is talking too quietly. I have heard of people having to snip out a couple of resistors from the EIS board to make the sensing circuit sensitive enough - I don't know which ones, that is why you need to call GRT, and it was over a year ago so there may be another fix. Emag may also be able to put out 12v, don't know if that is of any use to the EIS.

So, I think you have a I/O incompatibility problem, with the EIS the easiest to fix by increasing its sensitivity.

Pete
RV-6A with Emag, mag & EIS-4000
 
penguin said:
So, I think you have a I/O incompatibility problem, with the EIS the easiest to fix by increasing its sensitivity.
Click to expand...

Sounds pretty reasonable to me; the wiring seems stone simple, easy enough for even me, so I figger I could rule that out. On the pulse count, like Paul said, whether it's set at 1 or 2 pulses, it should show something... it looks like the Pmag isn't talking to the EIS. Maybe it's just shy...

So I have this tach glitch and an oil leak from an oil cooler line, but at least the engine runs! The oil leak is my fault; I replaced a straight end fitting on the hose with a 45 deg end and had some trouble getting it on straight, so big surprise, that's where the leak is. Duhh.

I was hoping to have this thing done by LOE and chase Paul out there, but oh well, maybe next year.

**one last thing; you just gotta love the internet and the RV community! I was about to post this when an email popped up from Walter Tondu with an instruction sheet from GRT on how to fix this exact problem. Yeaa, thanks Walter!**

John
 
It was a pretty simple job, just as Pete described; open up the EIS box, clip a resistor and remove a capacitor from the middle circuit board. Easy!

Worked like a charm; cranked up the engine a couple of times today and the tach works fine. Need the drawing?

John
 
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