At cold start the ECU will adjust ignition timing, fuel ration and I believe even cam timing to quickly bring the Cats up to operating temperature. (Cats don't function well when they are cold). This is also referred to as "Cat light off". So simply put, during cold start, part of the combustion process is still ongoing when the exhaust valves are opening. This results in hot exhaust gasses (to heat up the Cast), a different exhaust note and potentially a smell.
__________________
Black Fangs // Black rear Valance // Berk CBE // COBB post MAF tubes // K&N drop in filters // Setrab Oil Cooler // Stillen Sway bars // Z1 SS brake lines // Stillen brake cooling kit // Harness bar //
|