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Only when warm. Many modern gasoline burning vehicles are extremely stinky when cold. As I understand it, they deliberately run rich when first started to help
by amluto 5y ago
Only when warm. Many modern gasoline burning vehicles are extremely stinky when cold. As I understand it, they deliberately run rich when first started to help heat up the catalytic converter, and I wonder if this is a case of optimizing for the wrong thing.
EVs are, of course, emission-free when idle. (Although, oddly, at least some Teslas still can’t open or close their windows when in the off-ish state.)
- LegitShady 5y agoMy understanding of the cold-rich start was not anything to do with the catalytic converter. Cold air is more dense and contains more oxygen. At the same time, when the engine is cold gasoline is harder to vaporize and doesn't vaporize properly, and also can condense on cold engine parts. Running rich while the engine is cold allows additional gas to offset both of those issues. When the extra un-combusted gasoline passes through, a secondary air injection system allows the fuel to be burned up before reaching the catalytic converter and does heat it up faster, but this is a secondary benefit rather than the primary benefit.
- theodric 5y agoMy 23-year-old V12 7 series has electrically heated catalytic converters for this very reason. Thanks to those, according to German regs it qualifies as a ULEV! I think it still stinks at first start. Also, the cats cost two grand each to replace and the car requires a second battery to power them without draining the main starting battery so much that the car won't turn over. That's probably why we don't see more of this...
- ars 5y ago> Only when warm. In that case you should prefer idling, rather than stopping the motor and letting it cool down.