B. Mivec Tuning (Evo 9 only)
The Evo 9 has variable cam timing on the intake cam. It varies the cam timing from a value of 0 to a value of 30 in the VVT table. You can input values beyond 30 in the table but nothing really happens. Those who specialize in ECU disassembly on the Evo have not figured out a way to log cam timing. I am pretty sure that in due time they will figure it out. When that happens we can figure out exactly what load cells we are hitting across the rpm range and create far better maps. In the meantime a lot of DIYers have experimented with cam timing and posted their maps and their findings (
http://forums.evolutionm.net/showthread.php?t=210569&highlight=mivec+tuning)
All the maps tend to follow a similar pattern: cam timing advance is low in the lower rpm, but as the engine speed increases cam timing is advanced. Cam timing advance reaches its peak around 3500-4000 rpm and then cam timing is gradually brought back close to zero by 6500-7000 rpm.
Most DIY tuners start by using the Evo 9 JDM RS map. That map forms the basis of 90% of Mivec maps that are posted and used in the VVT table. Here is what the map looks like:
Most DIYers change the numbers in the “island” that has 24 in it to 28.8 and save the map and flash it into the ECU. Others change the entire 28.8 numbers to 30, save the map and flash it into their ECU. This is a really good map.
I tinkered with mivec and was able to come up with a map that I really liked. It is a fusion of two maps. The first map was posted in the Mivec Tuning thread on Evom and the second map was created by John Bradley who is the resident mivec guru on Evom. I took the top end (load cell 70 to 100) from one map and fused it with the bottom end from another map. I was very surprised by the increase in low end snappiness of my Evo. The car felt like an NA car. You can put it in high gear at low rpm and simply touch the accelerator and the car goes. I thought it was only in my mind, but when I tested it on other Evos, the impressions of the drivers were the same. Two caveats about this map: First, it will slightly increase your idle by about 100-200 rpm during normal driving. Second, after you hammer on the car for a while, your idle will go up to 1000 rpm. If you can tolerate this, then go ahead and use the map. If you cannot, then use the JDM 9 RS map.