FD3S:Twin Turbo Overview
0 to 3,000 RPM
- In this RPM range, boost is produced by only the Primary Turbocharger. At this time, most of the the exhaust is directed to the Primary Turbo by the Turbo Control, and the Secondary Compressor is isolated from the Primary by the Charge Control. Boost pressure is regulated by the Turbo Pre-Control.
3,000 to 4,500 RPM
- In this RPM range the Turbo Pre-Control valve is almost fully opened and preliminary rotation of the Secondary Turbo has begun, any boost pressure from the Secondary Turbo is vented via the Charge Releif Valve to the air cleaner
At 4,500 RPM
- At this time, the Secondary Turbo is at full preliminary rotation speed, the Turbo Control is opening, Charge Releif and Charge Control allows Secondary boost to be added to the Primary boost.
4,500 to Redline
- The Turbo Control is fully opened, and boost pressure is created by the Primary and Secondary Turbochargers. When both Turbochargers are actuated, boost prerssure regulation is preformed by the Wastegate Control.
From the above description, there is not much happening when only the Primary Turbocharger is operating. However, at 4,500 RPM when the change over occurs, lots of solenoids and actuators are changing operation. This is when most of the problems occur.