What the delay does
In closed loop boost control, the Nexus doesn't start correcting duty as soon as you're on boost. It first waits for every closed loop activation condition in your setup to be met. The delay adds one more step: once they are all true, the ECU waits this long before it starts correcting.
The reason is that boost usually overshoots a little and wobbles as it arrives at target. If the controller reacts to that wobble, it adds its own swing, and you end up with boost that waves up and down. A short delay lets boost settle so the controller corrects real error, not noise.
Choosing a value
Typical values are between about 0.05 and 2 seconds. A good guide is how long boost takes to climb from the control point offset to the target on your car. Log a few pulls and measure it:
- Too short: corrections start while boost is still settling, so you see oscillation around the target.
- Too long: the controller joins late. If the base duty is off, boost can sit above or below target for a noticeable time first.
The delay can only do so much. If boost is well off target when the delay ends, the real fix is a better closed loop base duty table, not a longer or shorter delay.
After the delay, how hard the controller corrects comes down to the proportional, integral and derivative gains.
