What causes car to misfire at higher temperatures and elevations?

THERE are a couple of reason's due to the higher temp,the fuel in the cylinder detonates ,and the amount of oxygen molecules per square inch is less. also what is happening in the cylinder when spark occurs under normal conditions the fuel burns across the top of the piston. In detonation and miss fire the fuel explodes at once on to of the cylinder. another aspect to remember is that the higher you are above sea level the less oxygen thee is.