Ok while on the road hauling today, I was running about 850 deg after turbo, and had to let off to shift. upon letting up on the pedal, I lost my pyro-all the way down to 0. when I got back into it in 4th gear, it came back up almost right with the boost needle. Same deal all the way home. Except it sweeps up to the usual numbers and wont go higher like the boost will, back off and she drops right back down.

Im stumped. I check my connections and atleast they seem still tight.

 

Double check that you have a good ground

 

My guess is that you either have a bad connection or a bad t-couple. EGTs don’t swing that fast or that far (zero).