EVO 9 MIVEC control with aftermarket cam fitted

Hi Andre,

I have seen many person fit larger aftermarket cams, using the OEM ECU that was re-flashed, but gives to lumpy idle, that being said, I am assuming that the OEM cam control target remains the same, which in some cases has up 30 degrees of advance. In this case what would be an accepted amount of advance, and I am supposing that the fueling would have to be adjusted as well, to achieve an acceptable idle.

There's nothing wrong with using an aftermarket cam with the factory ECU, and for the most part the aftermarket cams designed for the stock engine are developed to ensure there's no valve to piston contact at either extreme of the adjustment range. The MIVEC mapping is still adjustable with suitable reflashing software (I use ECU Flash) though as the stock targets won't be optimal for a larger cam. The only way to find the ideal cam targets really is to use the dyno though. The fuelling is likely to need some adjustment but by virtue of the MAF sensor this is normally still going to be pretty close when swapping cams.