Not hard to understand. When you start a cold engine and after oil pressure comes up when you go to fast idle the additional boost provided generates enough heat to get more complete combustion of the fuel.
"But here's what Cummins told me directly. My engine has a warm up protection feature that won't allow me to fast idle or use the throttle until the engine is ready to perform and everything is up to pressure and temperature to prevent harm. This is what's coming directly from Cummins."
Well that is easy to check. I bet starting with a cold engine, as soon as you can go to fast idle you can drive. It won't be at operating temperature.
Bill
