When tuning closed loop boost control, does it matter which gear I do the tuning in?

 

it depends on the setup, but probably. the average car will boost higher in a higher gear, the engine revs more slowly, so there is more time for boost to build.
i think best practice would be to use the same gear for most of the tuning, and then trim it out as needed.

 

Thank you. I am running simplified sequential and a large exhaust. I noticed boost was different based on gear but I wasn't sure how much difference it would make when tuning closed loop boost control.

 

the stock ecu has a 1/2 gear switch and the manuals mention there is different boost control when those are on, although since its the same, its hard to say what it does

 

What kind of ECU are you tuning? Typically a boost control tuning strategy for any ECU would use this generic sequence:

1 - Baseline boost control on waste gate springs alone to characterize/log the minimum boost you'll expect see in each gear (i.e., no ECU boost controls operating; plumb the waste gates so they see boost pressure at all times). The data collected (i.e., consistent max boost for each gear) will inform the next step.

2 - Setup your ECU to support Open Loop boost control - Goal here will be to characterize how much waste gate duty cycle you'll need to consistently hit the desired boost targets for each gear, which are typically higher boost levels per gear than what you characterized on WG springs alone (step 1)

3 - Setup your ECU to support Closed Loop boost control for your desired boost targets by gear. The data you collected in step 2 informs the waste gate duty cycles (DC) you'll use as starting points for closed loop control, this way the closed loop control algorithm will have less work to do adjusting the waste gate DC's to hit your boost target consistently, and it will make it easier to adjust the ECU's default closed loop boost control PID settings if necessary.