Tag: TCV

Turbo S80 TCV & Vacuum Line Routing

The pressure from the outlet of the turbo presses on the wastegate diaphragm to keep it closed. When the ECU decides there is enough boost, it stops allowing the air from the turbo outlet from going to the wastegate actuator and allows it to go to the compressor inlet tube. The system is a pulse width modulated system meaning it is never “always on”, but instead cycled on for longer periods of time to increase boost, and shorter to decrease boost. When the TCV is off, air from the compressor is dumped to the compressor inlet, and the spring pressure in the wastegate is what regulates compressor outlet pressure.

Fast Friday Volvo Performance and Tuning

Fast Friday #4 — The Boost Variance Problem

Boost pressure issues seem to be the #2 issue in the Volvo Performance world beaten out only by vacuum leaks. Boost pressure control in the 1994-1998 models is a pretty simple system but for the ECU to manage boost correctly it relies heavily on known base values and settings. If these settings are off or if there are mechanical issues then the boost control system can be out of whack.