IAC question...

[Paul Workman]

Originally Posted by XfireZ51

Paul,

The crispness of the throttle or the sensitivity of the throttle to changes is not dependent on the SPT opening or closing. I'm describing what I feel even at minute throttle changes, cams or no cams. I have done that for both configurations. The IAC position is dependent on throttle opening not the other way around. There are delays and filters for IAC opening and closing that follow the throttle position.
When tuning, the objective is to minimize the ECM intervention. Prior to computerized engine management, u tuned a carb to maximize vacuum. Same concept w Min Air Adjustment except that u DO want to leave some margin for the IAC to intervene in cases such as coast down or sudden throttle closing.
In a tuning strategy, u limit the amount of IAC steps for part throttle but maximize it for WOT to get as much air as possible. So better response botom to mid range, top end more air. Can also use the delays as a means of controlling rpm drop when shifting.
When the secondaries are disabled, I eliminate the delay in the calibration.

Ah! Gotcha, Dom. I think we're in "violent agreement" - for the most part (including the IAC setting vs. idle air adjustment - I meant to say that the process is iterative, but to be clearer, the throttle air set screw is adjusted, then the TPS voltage optimized, and then the IAC counts are checked to see what the net effect of the idle air screw was...if that clears it up?)

However, I don't think you meant to imply the SPT actuators don't affect the throttle response (on a stock motor). In fact, as you know, there is a mechanical delay (the SPTs don't open instantly!), and because of that, a necessary interim injector delay is programmed in the calibration. So, the net result, as anyone with the secondary delete mod may know, both of these delays are eliminated/moot, resulting in a very crisp response to (WOT) changes...I think is the point.