wow...

A datalogger is used to keep track of critical engine and sensor behavior. It becomes necessary when you start modifying your car, i suppose, but it's a must when you begin to f*ck with your a/f ratio (i.e. when you start using your afc). It monitors knock, timing, fuel trim, etc....everything your ecu monitors. It is an essential tool when tuning a dsm at home in conjunction with an afc.