Originally Posted by Peter J
Does anyone know what re-mapping is?
The engine electronics read all sorts of variables: throttle position, engine rpm, O2 content of the exhaust, etc, and the computer decides how to change the amount of fuel injected and alter ignition timing to suit the current conditions. For example, if everything else remains the same, but the throttle is advanced, the computer will most likely increase the amount of fuel injected, and advance the ignition timing a bit to get the increase the rpm desired.
The mapping is exactly how the computer responds to differing inputs. You can change (or re-map) the responses for whatever you want to enhance, be it low end power, fuel consumption, whatever. Usually, the mapping is tuned for overall driveability and smoothness across the rpm range.
This is a very general explanation, not all of it is necessarily applicable to E-Tecs.