Engine control unit / Engine management

Whenever i browse thru certain malaysia car club forum , i sure get some term like " self learning " , " re-adapt " and bla bla ... But when i browse those foreigner car club , i can't find those term . :P . That is weird . The reason is they really understand functional of ecu . Some of them really expert in reflash flash memory chip , eeprom & eprom of ecu . They did explained how a car engine management unit mapping working . Those term at above that alway mention by malaysian is referring to close loop system . Close loop system is designed for emission control purpose and enable engine to work at perfect A/F no matter low revving or high revving . Fuel economic also need close loop system to be in place . A close loop system needs various sensors work as feedback to ecu , so ecu able to adjust air fuel ratio accordingly . Like siemen EMS700 for campro , O2 sensor and manifold absolute pressure sensor (MAP sensor ) will work parallel to ensure A/F ratio at certain throttle angle and rpm as close as A/F ratio stated inside A/F mapping . So when you try to offset the MAP sensor reading before reach ecu with piggyback , A/F ratio will change either lean or rich . That is still not enough to fool ecu , because close loop system require ecu to compare O2 sensor reading with MAP sensor reading and A/F ratio target . One of the element change and violet A/F preset value , ecu will ignore it and trim fuel to achieve A/F ratio as per preset A/F value . Like you want to make A/F lean , you use piggyback like AFC neo to change the MAP sensor signal voltage from high to low . Yes , you manage to change the actual A/F from rich to lean . After a few second , ecu will trim fuel to change actual A/F ratio as per preset A/F with help of O2 sensor . If preset A/F ratio is 14.7 +/- 0.5 , any actual A/F ratio that out of tolerance will be tuned back to nominal . So you can not just cheat ecu with offset MAP sensor voltage , you have to offset O2 sensor signal as well . For NA , is not a big problem just you cannot get the after tuned performance to last long . For bolt on turbo , you may blow your engine if ecu change actual A/F rich to lean during boosting . You need a piggyback that can change O2 sensor signal as well not MAP sensor alone !!