My new favorite camshafts...the new Skunk2 Pro-series lineup. These cams feature large primaries which benefit midrange, and a revised ramp angle to improve throttle response. Only downside to them thus far, is that they do not stack up in the higher RPM range compared to the BC5's I had previously.
Having large primaries creates problems for the stock idling system. The Idle Air Control Valve (IACV) is a solenoid that moves a valve back and fourth, allowing air to bypass the throttle plate, and stabalizes the idle. This is user controllable in softwares like Crome, where you can preset the duty cycle. This feature works well with other camshafts that have larger than stock primaries, but the Pro-series primaries are so much bigger, you cannot rely on IACV duty cycle alone.
The first step is to prop the throttle plate open just a hair. There is an adjusting nut on the underside of the throttle spring, operated by an allen key, with a small 8mm nut locking it in place. This process is slightly tedious, as it is hard to adjust the throttle stop without removing the throttlebody, which I ended up taking on and off maybe a dozen times to get the idle perfect. If you shine a flashlight through one side of the throttle plate, you want to be able to barely see the light from the other side. Someday I will go and take my throttlebody off and count the number of turns to full close to make this procedure easier, but for now you will need a little patience and trial-by-error.
Once you have the throttlebody back on, you can begin to tune the idle. Allow the motor to reach operating temperatures before tuning, otherwise you may interfere with the ECU controlled warm-up function. Target idle should be programmed at 850rpms. Idle timing should be between 20-22deg, and air-fuels should be between 15.5-15.0:1. Having the capabilities of real-time-programming makes this part a breeze. Start with IACV duty cycle at 50%, and if your idle still isn't ideal, you can try adjusting the duty cycle. If adjusting the IACV duty cycle does not work, you can use the adjusting screw ontop of the throttlebody, this creates the same effect as adjusting the throttlestop, but on a much smaller scale.
The key is patience, it is possible, you just need to work to get it!
Your car should warm up and idle just like it did from the factory! Mine idles at 850rpms +/- 50, just like the Helms manual suggests! The warm up is linear and does not hunt nor does it idle too high.
Check back for a video of warm up and idle, pictures, and more precise details on how to adjust the throttle stop.