Mazda Speed 6. Manual - part 5

01 ENGINE

22

Waste Gate Regulator Solenoid 
An intake manifold connection to the waste gate actuator opens the waste gate.  The 
waste gate regulator solenoid regulates boost pressure from the intake to bleed off 
pressure, preventing the waste gate from opening too early when maximum boost is 
needed.

There are three operating modes for the Waste Gate Actuator solenoid:

Solenoid off, waste gate closed, building boost

Solenoid off, waste gate open, releasing boost

Solenoid on, waste gate closed, building maximum boost

1. Solenoid off, waste gate closed, building boost

Cool Fresh Air

High Pressure Hot Air

Exhaust Gasses

1.

2.

3.

Waste Gate is closed

Waste Gate 
Solenoid

01 ENGINE

23

2. Solenoid off, waste gate open, releasing boost

When boost pressure is high in the intake, the boost pressure from the intake 
manifold acts on the waste gate actuator to open the waste gate, slow down the 
turbine, and prevent an over-boost condition.

Cool Fresh Air

High Pressure Hot Air

Exhaust Gasses

01 ENGINE

24

3. Solenoid on, waste gate closed, building maximum boost

The waste gate regulator solenoid tunes the opening rate of the waste gate to help 
build maximum boost when needed.  The solenoid controls the line from the intake 
manifold to the waste gate actuator.  When the solenoid is energized, it bleeds off 
pressure routed from the intake manifold to the waste gate actuator. The solenoid 
bleeds this pressure back into the turbocharger inlet.  

Cool Fresh Air

High Pressure Hot Air

Exhaust Gasses

Waste gate is 
Closed

Apply pressure is bled 
off from the wastegate 
actuator back to the 
turbocharger inlet

01 ENGINE

25

Air Bypass Valve
The air bypass valve protects the intake manifold air ducts, passages, and sealing 
gaskets from damage due to over-boost.  Over-boost can occur when accelerating 
the vehicle and closing the throttle suddenly.  When the throttle closes suddenly and 
boost pressure is present in the intake manifold, this valve pops open and vents the 
pressure back to the inlet side of the turbocharger.   

Air Bypass Valve - Closed (throttle open)

Air Bypass Valve - Open (throttle closed)

Throttle open and 

high boost

TURBO

WASTE GATE 

SOLENOID

Valve is open

TURBO

Manifold 
vacuum

 

Throttle closed 
and high boost

 

WASTE GATE 

SOLENOID

Cool Fresh Air

High Pressure Hot Air

Manifold Vacuum

Cool Dense Air