JakeFusion

iTrader: (7)

I wouldn't drill a hole. Either go SD or raise the idle slightly. The tune needs to be spot on - especially for your injectors. If you're running larger injectors and the tune is off for them, that can really mess with your idle quality as well. In fact, it's one of those things people often overlook.

Alvin@PCMofNC

The tune especially fueling is the cause for most idle issue however there are points where the stock idle bypass hole is not enough.

If you have a whopper cam or stroker you are going to need to get more air pass the throttle body somehow. The options are opening the blade via throttle stop or drilling a hole. I prefer drilling a larger hole than stock because I feel like this gives you a much more consistent result.

Look at flow across a valve or gate. Very small changes make huge percent changes in flow. I'm on my phone but later can post a picture. Google valve flow and you'll see what I mean


Having said that either way the effective area vs iac table will need to be fixed which is a easy process for a experienced tuner.