Unstable Readings SV-EMS

[badia358]

I have been getting unstable readings for a number of items that are monitor through the SV-EMS. RPM and Battery voltage seem to be the most affected. It used to be mostly at full RPM, but today even at about 2000 RPM the readings were bouncing all over the place. Plus the AMP reading has never worked, but is now reading 4 AMPs.

I thought that this was a grounding issue, so I made sure that all grounding was good.

I am assuming that there is a problem with the SV-EMS, but before I go and buy a new one, I wanted to check and see if anyone has seen this before. Thank you.

 

[KRviator]

I had an issue two flights ago where my ampmeter reading was a little jumpy and then went to -45A. I checked everything FWF but found nothing wrong and am monitoring it on subsequent flights.

That your ampmeter never worked seems strange, it is a nearly bullet-proof sensor. Dumb question, but those little in line 1A fuses aren't U/S are them, and you have continuity from the amp shunt screw to the EMS plug pin?

 

[jakej]

I'd recommend that you redo your small terminal (shunt) crimps & use internal star washers where you can, this is the area that usually is the cause of those issues IMO. KR knows I do a lot of installs & I don't have those issues since using the above method

 

[badia358]

For the AMP, I have checked continuity and even shorted the 2 wires going to the EMS expecting a zero reading, but did not. That is problem one.

My other problem is still all the unstable readings. Thank you.

 

[Dynon]

This does sound like grounding from here too. Is your EMS ground very well grounded to your engine block?

 

[jc2da]

I had something like this happen. I plugged the connector into the EMS unit but did not bother tightening up the lock screws on each side. I figured it wont come out.

Lo and behold, crazy bouncy readings all over the place. In the process of debugging, I double checked the connectors and decided to tighten up the lock screws. Yep, fixed.

Of course, all the lock screws should be tightened up, but i would just confirm they are.

 

[badia358]

Thank you all. I will go try the suggestions here. Hopefully this coming weekend.

 

[bwok]

I had bouncing amps indications like you had.

The solution for me:
Gave the inline fuse and its connecting terminals a fine sandpaper & I got stable amps indications after that!