Why do some companies modify ECMs and/or provide ECM piggyback modules?
Supercharging-related ECM modifications originated with a roots supercharger system. Because of the heat produced by roots technology, it is necessary to retard the ignition timing of stock fuel injected motors when utilizing a roots supercharger. Power gains with a roots supercharger are limited to begin with, and fell to around 15% with the power-robbing effects of ignition retard. To address the opposing needs for ignition retard and more power, the ECM was modified to not only retard timing, but to also raise the rev limiter – and allow a higher power claim at the elevated redline. Others have since followed, and while manufacturers try to position their ECM modifications as a good thing, the fact is that any need to retard ignition timing is actually an indication of excessive heat. The same can be said for any supercharger system that requires EGT warning lights. As for ECM piggyback modules, although these were originally designed to also retard ignition timing without being for
