Is the cursor hitting several boxes? I generally try to get the entire idle area blocked out until I get the idle where I want it. In other words, it may idle mostly in one cell, but the cells surrounding it will all be highlighted and changed as one. If it even touches the edge of another cell it's "borrowing" the numbers from it, which can cause wild rpm swings.
I like to allow the computer to control the timing, especially at idle. I get the a/f right first. By the way, a thought on this. Do not get hung up on the numbers. Your particular cam/intake/engine combo may not be happy idling at 14.7:1. Give it what it wants, it will make settling it down much easier. Many of my engines would not idle happily in the 14:1 a/f range, yet you richen the idle to say 13.5 they were noticeably smoother, vacuum came up, etc. Give them what they want.
Back to idle timing. Once you get the a/f to a happy spot, with all the boxes the same number that it's hitting, start on idle timing. I usually want at least 20 degrees at idle in the main timing map. Again, keep all the boxes it's idling in the same, as if it hits a box with a higher timing number it makes the idle speed fluctuate. I also like to let the computer use timing compensation at idle, up to 8-10 degrees usually depending on how far off the actual idle rpm is from desired. This really steadies the idle rpms.
One other thing, once you have the engine up and fully warmed, you need to set the throttle blades properly, or at least verify that they are set properly. With it fully warmed shut off timing compensation at idle, and command a real low rpm number, like 500 rpm. This will force the idle air control to shut fully and the only air holding the idle speed is the throttle blades. Set the blades to hold the minimum idle speed you want fully warmed, just like with a carb. Reset or check your tps setting as it will likely move. Then turn the idle timing compensation back on, and re-enter the correct idle speed in the computer. Now you have full use of the iac which can help tremendously with idle speed fluctuation. If the blades are not open enough the iac is having to be open too much just trying to get your desired idle rpm, and is useless for what it is supposed to be doing. This is very common.
Jody
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