A sequential twin turbo system runs on one turbo at low RPM for fast response, then brings the second turbo online as flow demand grows. The Secondary On RPM table decides the engine speed at which the ECU activates that second turbo. It can be mapped in up to three dimensions, so the switch point can shift with other channels you choose instead of being one fixed RPM.
Get it wrong and you feel it: too early and boost sags because the second turbo isn't ready, too late and the primary runs out of breath. Log boost, RPM and throttle through the changeover and look for a dip or spike.
It works together with Secondary Off RPM, which sets when the second turbo drops back out, and the pre-control duty cycle. Start with the sequential twin turbo overview and wiring. Need this screen? Ask us and we'll send it over with advice for your build.
