Voltage difference between TS and applied voltage

[Nitroking]

That's good to know, thank you!

So the other thing is, why is there a 0.5-0.6v difference from battery reading to TS? It can't be just a wiring voltage drop, it is a lot..

[Djovani_jr]

if tuner studio shows 14 volts, where should these 14 volts be in reality?
ecu terminals or battery terminals?

[jsmcortina]

Two different questions in this topic that I can see.
1. battery voltage readings
2. pressure sensor readings

1. Battery voltage
Changes in TPSVREF will have an effect on reported battery voltage. Tolerance of the measuring resistors will have an effect too, typically 5% resistors are used on the V3.0 board, so the error can be quite large.
Adjust the calibration so the voltage shown in TunerStudio matches the voltage at the ECU power power and ground.

(While working on this, you should also check for any voltage drops in your power wiring between battery, engine, alternator and ECU during running. You need that to be say 0.2V or less. If you are seeing larger voltage drops anywhere, find the source and fix it.)

2. Sensors
As Matt answered originally, the typical external pressure sensors are "ratiometric" and follow the applied voltage, so if the TPSVREF supply voltage is pulled down a little, the sensors will follow suit (in ratio) and the measured reading should be ok.

James

[DaveEFI]

That's good to know, thank you!

So the other thing is, why is there a 0.5-0.6v difference from battery reading to TS? It can't be just a wiring voltage drop, it is a lot..

Easy to measure the actual voltage drop. Connect your DVM between battery positive and 12v input to MS. Do it with the engine running, so MS is taking its normal load. Do the same on the ground side.