12-07-2021,
I have a c12 cat. Startup above 40degs hardly any smoke, below 40degs raw fuel smoke & smell. Fires right up not even a full revolution. Runs smoother cold and rougher when hot outside. When the air compressor builds air the motor surges until the air pops off at 125psi. Guy i got it from had a new ecm and cam put in the truck in Feb. 2021. Ecm was done at a private shop. Any ideas where to start with this?