VTEC control

The VTEC changeover point can be set anywhere within reason either using ROM Editor or by using the push button / interface box. The Hondata method of setting the VTEC point is better than any other piggyback computer. Why? Hondas have two fuel and two ignition maps. With add on VTEC controllers, the camshaft is forced to switch while running on the wrong fueling and ignition tables. This can cause fuel to be as far as 10% out and ignition to be retarded up to 6 degrees. Some VTEC controllers allow a coarse correction for fuelling, none allow correction for ignition advance. The best method is to switch the ECU tables at the same time the camshaft is changed. This is how Hondata modified ECUs function.

Most stock Honda VTEC points are set fairly well. Look to dyno figures in the Power Section to see the effects of different VTEC activation points. Supercharging in particular benefits from a lowering of the VTEC rpm, while high duration camshafts benefit from raising the VTEC rpm.