I got a 99 si and i just got an ls-vtec convertion,im using a apexi neo controller for vtec purposes, my ecu it was reprogramed from JET for my stock B16 with bolt ons.,it was working good for a week now my car its acting crazy! sometimes vtec don't kick in,can't go over 5500 rpm and even lost all the power. The guy who install it told that i need i new ecu if that the case should i get an stock 99 si ecu or should i go other way! thanks!

 

Buy an OBD2b to OBD1 conversion and chip it with an LS/VTEC basemap.