Engine warm-up control method

In order to reduce white smoke emissions immediately after start-up, the present invention is a method for executing engine warm-up control using electronic control units, wherein start-up idle control, which does not perform the prescribed fast idle control, is executed until a prescribed period of time tl has elapsed after engine start-up, whereupon the amount of fuel injection is increased to execute fast idle control. Immediately after engine start-up, the fuel injection amount and number of engine revolutions are restricted compared to those during fast idle control, preventing a large amount of fuel injection and high number of revolutions while the piston wall surface temperature is low, and thereby significantly reducing white smoke emissions.