From An expert.. Andy Finkbeiner . 2 posts. First is more seat of the pants and experience. Second is more procedural and what I am looking for. They do go hand in hand though for setting idle timing, rpm and AFR.
First post.
"""First thing to do is to get the car running and warm up the engine so you can work on the hot idle. Once you have the engine warm you adjust the idle settings just like you would a carb. Slowly drop the idle speed and see how it does. Play with the ignition timing to see what it likes. Adjust the AFR to see what it likes. Adjust the throttle position to get the IAC into the correct location. It is exactly how you tune a carb engine except you don't have to change jets and mess with the distributor springs. You can do it all on the laptop by changing the values in the tables.
There are a bunch of Holley tuning videos on youtube so I'd suggest starting there if this is all new to you. It is like anything else. Once you know how to do it it is very simple but when you don't know how to do it it is intimidating. Watching a few videos will get you comfortable with the process of paging thru the menu and opening up the tables and stuff like that."""
Second post
"""You aim for minimum kPa when tuning. kPa is pressure. You want to aim for maximum vacuum which is the opposite of pressure. Your idle pressure should be around 50 kPa on a well tuned engine with a modest performance cam in it. That is 15 inches of vacuum. A race car might idle at 70 kPa while a car with a stock cam will idle at 40 kPa. When you adjust the timing and/or the idle AFR you shoot for lower kPa. The other way to do it is to watch the IAC position. The IAC controls the idle air flow so what you want to do observe what is happening to the IAC position as you adjust the timing and the AFR."""
