Every driver drives differently, eg family man drivers more conservitevly (sp?) than a 18yo lad whoc just got their license ... (just an example). Varibles can be adjusted such as, Transmission controle (kick down controle), economy controle, response etc. When resetting this is getting deleted and the ECU can relearns froms cratch. Comes in handy when the vehicles changes owner, you take ur dads car out for a spin and the ECU has always been used to ur dads slow acceleration etc.
Anyway comes in handy when modding the car as well (not particluarly with external mos :p), but anything from changing air filter (more air flow, hence ecu must learn to increase fuel mixture), over exhaust to cams and god knows what else.
To successfully reset the ecu u have to disconnect the +ive terminal, but touching that terminal to negatve or anything like that is just plain madness. Instead leave it off for at least 30min. The ECU is capapable of holding the memory for that long due to the fact if u just wanna do a simple battery swap u dont wanna loose the memory. You can see when the ecu has reset on ur dash and u turn the key to accessories that a test is run by the ECU and warning signal light up. Then you simple turn it off and back on and u r ready to roll ...
Well that the dash lights up in EF to BA falcons ... dunno about EDs ... but same thing i spose
