Surefly magcheck issue on EIS4000

roadrunner20 · #1 08-19-2019, 10:09 PM

I've just replaced one slick mag for a Surefly EI. On magcheck, I'm gettng a zero reading for the EI. I'm currently using dual 27k resistors on my magcheck switch.
Before I start replacing that resistor, I thought I'd check to see if anyone else has solved this.

Robin8er · #2 08-19-2019, 10:32 PM

How does your tach work? I have the same issue with my lightspeed ignition. Mine measured RPM off the electronic ignition, so when I turn it off the rpm drops to zero.

roadrunner20 · #3 08-19-2019, 10:39 PM

Quote:

Originally Posted by Robin8er

How does your tach work? I have the same issue with my lightspeed ignition. Mine measured RPM off the electronic ignition, so when I turn it off the rpm drops to zero.

I have separate wires running from each p-lead with a 27k resistor to a toggle switch. This enables me to get individual readings sent to the EIS. When switched to the EI, it's now reading zero. Surefly suggests a 18k resistor or less. If someone has done this, it will prevent me from swapping one out until I get the proper one.

lr172 · #4 08-19-2019, 10:55 PM

Quote:

Originally Posted by roadrunner20

I've just replaced one slick mag for a Surefly EI. On magcheck, I'm gettng a zero reading for the EI. I'm currently using dual 27k resistors on my magcheck switch.
Before I start replacing that resistor, I thought I'd check to see if anyone else has solved this.

Your EIS needs a large resistor to safely catch a pulse off the the coil of the mag. However, most any EI will send a nice 12 volt square wave tach signal and therefore no resistor should be used between it and the EIS. I would guess that the surefly provides a traditional tach signal (12 volt pulse) and a 30K resistor will make it unreadable for the EIS. There simply won't be enough current left for the EIS to pick it up. However, being a certified replacement, it is possible that they are trying to emulate a traditional mag signal, though I doubt it.

Larry

Skid · #5 08-20-2019, 06:40 AM

I also have a Lightspeed ignition on one side and a mag on the other. I have a resistor on the mag but not one on the Lightspeed. I had a switch like Dan to allow either ignition to display on the EIS on my EFIS.

I upgraded to the remote EIS R66 last year. The remote EIS allows me to configure all the settings in my GRT EFIS and has two tach inputs so it no longer requires a switch. My understanding is the newer EIS 4000 also has two tach inputs.

lr172 · #6 08-20-2019, 06:56 AM

Quote:

Originally Posted by Skid

I also have a Lightspeed ignition on one side and a mag on the other. I have a resistor on the mag but not one on the Lightspeed. I had a switch like Dan to allow either ignition to display on the EIS on my EFIS.

I upgraded to the remote EIS R66 last year. The remote EIS allows me to configure all the settings in my GRT EFIS and has two tach inputs so it no longer requires a switch. My understanding is the newer EIS 4000 also has two tach inputs.

That's interesting. My EIS 4000 had two tach inputs. Didn't realize there was an older version with only one.

Larry

roadrunner20 · #7 08-20-2019, 07:09 AM

Quote:

Originally Posted by lr172

That's interesting. My EIS 4000 had two tach inputs. Didn't realize there was an older version with only one.

Larry

Yes. I spoke with GRT & they stated the newer models DO have 2 inputs.
Mine is a 2005 model, which at that time, only provided a single input.

Skid · #8 08-20-2019, 07:11 AM

Quote:

Originally Posted by lr172

That's interesting. My EIS 4000 had two tach inputs. Didn't realize there was an older version with only one.

Larry

There was, mine was circa 2003.

roadrunner20 · #9 08-20-2019, 07:16 AM

Looks like my first attempt will be to bypass the resistor completely.
Thanks for the info.

I'll update this this thread & inform GRT & Surefly, so they can update their docs.

Canadian_JOY · #10 08-20-2019, 07:35 AM

The better alternative would be to purchase the magnetic sensor that screws into the vent plug hole in the magneto body. This sensor uses the spinning magneto gear teeth to provide an output to the EIS. The beauty of this sensor is that it provides that RPM signal even when the P-lead is grounded.

The sensor I use is from Advanced Flight Systems. I know other vendors also supply similar sensors. Dead-easy to install and doesn't have anything to do with the very noisy P-lead signal - no resistors, nada. Power, ground and signal, that's it.