well it helps if ya say its a gas od diesel engine to start
if its diesel engine it has 4 diesel heater in each cilinder usually after 150 000 kms or sometimes before its adviceable to change coz it doesnt heat as before and the end of the heater that is inside the cilinder cant get incandescent so its a sinonym of a bad start of engine.
and more if just one of these heaters is failing ...the engine might start but till it heats makes lots of smoke