Quote:
Originally Posted by Walt White Coupe
I could be wrong but I think only two things happen in a cold start. The engine idle speed is kicked up for 30 to 40 seconds and the exhaust flaps are opened.
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I think that in addition, the mixture is run slightly richer to heat up the catalyst quicker.
quote:
The purpose of the secondary air system is to perform exhaust re-treatment during the engine warm-up phase. During this process, fresh air is blown directly into the exhaust manifold thus increasing the rate at which the catalytic converter is heated (thermal post-combustion of exhaust gas)
end quote
This might contribute to the loader sound during that initial cold start