I got my auto meter pyrometer installed today in my big Massey... the one with the 903 Cummins.Just like the instructions said, it buzzes when the gauge sweeps up and down (auto calibration). But, today was around 30 degrees outside, and the gauge said it was 300-400, with a stone cold engine.I didn't want to fire up the engine (takes too much fuel just to hear it run, and it wasn't plugged in either).Do these things need some time to 'learn' the curve? or do I have a dud?

I'm guessing it's powered when the key is on?I hate to say it, but you probably need to start it to see what she says. . .

Yes, It is a 'key on' type gauge. when 12volts are supplied, it will sweep up, then down to zero, then settle on the actual read temp. (power on calibration). It supposed to run this test each time it's keyed.If it warms up today, I might light the fire and see what it does!

Having had electronic calibration-sweep EGTs in the past, I've not seen one settle that high on a cold engine. I'd be curious as to what it says once it's started..that thing should settle on/near zero if it's 30*F where it's sitting. I've no experience with the AutoMeter Cobalt ones. My Autometer UntraLight will show 400*F at idle, which I know it's not that hot. I don't trust my AM EGT; just sayin'...