EMU Black ground question

So I've asked a friend of mine to make a plug and play adapter for my Audi UrS6, 2.2t AAN engine, the car is running fine, the only issue i have observed is that my tacho is jumping erratically, especially when I turn the lights on. Although EMU reads rpm fine, I have checked tacho output cable and have not seen any problems with this.

So I had a look at all the pins connected, apparently the Power ground on my EMU Black is not connected to anything. Still the car runs fine. Should I connect it to the chassis or engine, is it that important though?

I have constant 14V on the recorded logs, so no voltage loss here.

Connected power ground to the chassis, haven't seen any improvement on my tacho.

Although I guess it's the tacho problem, since the car is old, I have removed the clocks and will check if the contacts are fine.

Another question , I have observed that when I turn on the lights, heater or even windscreen defrost function, my lambda would go rich.

I was thinking this may be due to the injector wrong deadtime calibration, I am using FID 1000 injectors, with 4 bar pressure (stock FPR Audi UrS6)

I have measured voltage drop on the alternator and also on the battery, also checked the logs, and usually it's 14.3-14.4v with all lights and heater off and would go to around 14.15V with everything on.

Would this indicate an electrical issue, since i'm still in the 14V+ range of the table, it's odd that I see changes in my lambda value by .03-.07.

I have properly tuned my VE table to hold my target lambda and i'm pretty sure it's something else.

The power ground should be connected to the engine block ideally. The issue you're having with the tacho could be related to the particular tacho. I've had a few ECUs that needed a pull up to 12V in order to correctly drive the tacho. I'd be inclined to fire an email to ECU Master and ask them if there's anything special you need to do to run the tacho on your Audi.

Thanks for your reply, but it has a pullup resistor already built in for tacho output.