Wiring 14point7 wideband, connect LSU 4.9 to power source only when engine is running
 

I'm wiring my new 14.7 wideband data logger in my 85 911 Cabriolet and the instructions say to only have power to the unit when the engine is running. I'm thinking of pulling power from the top side of the fuse for the fuel pump as it only comes on when the engine is cranking. Is there a better fuse location that is switched and only hot when the engine is running? I'm searching my Bentley manual for a better fuse location than the two I'm currently using to power the unit but any input would be appreciated.

Safest thing is to get your DVM out and test each prospect. I personally would use the radio fuse.

They want to use the switched line so you will not burn out the sensor as it will be heated to bring up to operating temps.

I think I connected the power leads to fuses 7&8 which are both switched power. I was just a little confused about connecting to a power source that was hot when the engine was running. I figured the fuel pump fuse would do that since it is only hot when the engine is cranking due to the signal being sent from the DME relay.

What year model?
 

On most fuse panels from 74 forward, fuses 7 & 8 (from front of car) are the high beam headlight fuses which would not be "hot" unless the high beams are on!