High noise in TPS sensor wire when Wideband uses sensor ground

[79er]

On my MS3 box I am running the Sensor Wires TPS, CLT, IAT, ETC to the Sensor Ground Wire coming from the MS3.

The only Sensor Ground Wire that is not running to the MS3 Sensor Ground Wire is the Innovate Wideband Gage Ground Wire.

This Ground Wire is running to the side of the block. Sharing the same Ground location as all the other Ground Wires for the MegaSquirt ECU. 

 

With this setup I get little to no noise introduced into the TPS sensor wire. 

When the setup has the Wide Band Ground going to the MS3 Sensor Ground Wire, I get movement on my TPS Gauge, tripping EA, Cruize, ETC. The TPS will blip to 1.5 to 0 in a constant manner.

 

How can this much noise be introduced into the TPS Sensor Wire when it is attached to the MS3's Sensor Ground Wire? This is the recommend setup described on MSExtra for wiring in all Sensor Ground Wires to this Ground Wire.

[Ben280]

Wideband sensors have a heater circuit in them, so you don't want to ground that to the same point as other sensors. I don't think Innovative makes a distinction here with their grounds, so you are likely seeing the heater circuit influencing your TPS. 

 

If you're grounding all the sensors and MS pin 7 to the block, you've got other problems tho. The sensors should only ground to pin 7, and nowhere else. These sensors aren't necessarily "grounds" in the way we think of them for power circuits, they end up being more of a 0 reference voltage signal. 

Edited April 22, 2021 by Ben280
more info.