Temp probe RPM Air Gap

if they work anything like my electric sending unit for the autometer gauges you may have to ground the sensor too. I had to on both my vehicles with aluminum intakes. I just wrap a band clamp around the sensor then ground the band clamp with a female spade connector to the end of it.

Did you seal yours with Teflon tape? I've seen ground wires have to added because of that. I seal mine with pipe sealer and have never had to ground a sensor.