[First Bird]

The blue Tach wire can pick up electromagnetic interference and give a bad signal to your ECU.

I bought 1/8” braided metal sleeve to shield the blue wire. The “shield” only works if the sleeve is one continuous piece and is grounded in one - and only one - place. If the shield is grounded in more than one place it does not work right. Loops of interference form (or something like that).
I watched a video showing how much voltage was drained by grounding the braid. Really eye opening.

I cut and removed the blue wire from the factory loom. Put the wire inside the shield. Grounded the shield at the TB.
I crimped and soldered the blue wire and covered the braided blue wire with plastic wire loom. Why? So that the braid couldn’t touch metal anywhere and create a second ground loop.

Then I joined the braided shield on both sides of the connector by crimping it to a short wire that jumps around the connector.

I’m almost done with a FITECH 30002 install. Does this shielding work? I’ll let you know. And if anyone spots an egregious error in my work - let me know.