What you can do Don’t ignore the warning signs. If your car runs rough, smells weird, or the dash lights up, get it checked. A good tech will scan the system and track down the cause. And if you ...

The opposite condition, where too much fuel or not enough air is in the mixture, is called running rich. If your engine is running lean, it may be hard to start, accelerate poorly, or stall at idle.

It sounds like a title bout: the Lean, Mean Fighting Machine against the Chattering Classes. But no, both phrases popped up recently in readers' inquiries about their origins.