[vvijay]

Originally Posted by amit

1. In winter conditions, emissions from an idling vehicle are more than double the normal level immediately after a cold start.

Does anyone know why? I mean, cold start means closely packed oxygen molecules per intake charge = better combustion right? Could anyone throw light on this?

[B747]

Originally Posted by vvijay

Does anyone know why? I mean, cold start means closely packed oxygen molecules per intake charge = better combustion right? Could anyone throw light on this?

I think the reason is all engines has an optimal operating temperature and in winter while just idling it takes a long time to get into optimum temperature, also it has to be noted that in Canada winter mean sub zero temperatures

[a4anurag]

Originally Posted by vvijay

Does anyone know why? I mean, cold start means closely packed oxygen molecules per intake charge = better combustion right? Could anyone throw light on this?

Since the engine block, all parts are cold.. the environment also being cool/cold the warm up time needed is longer so the idling circuit makes the Air-Fuel mixture richer to maintain the RPM and heat the engine. This takes up energy and time so the combustion is not complete as when the engine is warmed up.

This is the reason for more emissions during cold start.

Anurag.