Abstract: A method for starting an internal combustion engine under cold conditions. The intake manifold throttle valve is held closed and spark ignition is suspended. Fuel and air are admitted into the cylinders and the pistons are cranked for a plurality of revolutions. During each engine revolution cycle, the fuel/air mixture is compressed and heated adiabatically by the energy of the engine starter motor, and the mixture is exhausted into the exhaust manifold. During valve overlap a portion of the mixture is withdrawn into the cylinder and recompressed in the next cycle. Additional fuel may be injected to replace lost fuel. After several engine cycles, the fuel/air mixture becomes heated to a temperature above the flashpoint of the mixture. Sparking is re-established to fire the warmed mixture, and the intake throttle valve is re-enabled. The first firing can provide sufficient heat to continue spark-firing of newly-introduced mixture thereafter.

Abstract: A method for starting an internal combustion engine under cold conditions. The intake manifold throttle valve is held closed and spark ignition is suspended. Fuel and air are admitted into the cylinders and the pistons are cranked for a plurality of revolutions. During each engine revolution cycle, the fuel/air mixture is compressed and heated adiabatically by the energy of the engine starter motor, and the mixture is exhausted into the exhaust manifold. During valve overlap a portion of the mixture is withdrawn into the cylinder and recompressed in the next cycle. Additional fuel may be injected to replace lost fuel. After several engine cycles, the fuel/air mixture becomes heated to a temperature above the flashpoint of the mixture. Sparking is re-established to fire the warmed mixture, and the intake throttle valve is re-enabled. The first firing can provide sufficient heat to continue spark-firing of newly-introduced mixture thereafter.