Topic for discussion.
In 2016 I experienced noisy 5v supply on Genboard V3.8 , usually when Vems bluetooth adapter is powered from EC36/28. I have not been alone.......
http://www.vemssupport.com/forum/index.php/topic,2500.0.html
http://www.vemssupport.com/forum/index.php/topic,2435.0.html
The bluetooth adapter appears to generate noise on MAP and TPS. In our application TPS DOT rate settings caused acceleration enrichments to be active ALL the time, while little added, it held off EGO and VemsTune and VemsDisplay gauges would flutter significantly...... No good. Adjusting TPS DOT rate settings caused hesitation. Removing the bluetooth adapter, Resolved the issue. External power supply of the Vems bluetooth adapter resolved the issue............ Vems bluetooth adapter creates noise on 5v supply when powered from EC36/28.
Today while looking at the schematics for another modification, I noticed that C69 (220n) capacitor on 5v feeding EC36/29 is not present on the board. Pin 29 is powered from Pin 28 via R142 and ground through C69.
Forgetting for a moment my basic knowledge of electronics, would installing this capacitor help reduce the noise generated by the Vems bluetooth adapter on EC36/28?............
just use other 5v source to power bluetooth 
or maybe power map from map supply as I understand you are using external map sensor? + your tps is wired from tps supply or 5v supply?
On my current box, I have DSUB9 on the back plate and factory wired with 5v on pin 9 for bluetooth making it a little difficult, but by no means impossible to power externaly without some sort of adapter. I've not experienced any noise on this box yet, but the bluetooth adapter will not power up after the ECU has been left off for a while. Powering on the ECU the bluetooth adapter doesn't even blink the LED. Unplug and re plug then away it goes. This isn't such a good thing as I had intended to leave the adapter connected to the box under the dash, for the Vems Disply.
To be honest, I've had loads of problems with the bluetooth adapter from Vems, on two different boxes and three different tablets, I've given up on it and just running with the Round AIM Gauge instead, it better suits the classic nature of the car
External power is of course an option and that is how we ended up running it, but it adds extra bulk that can get a little messy at times.
