Mechanical by-pass valve

When the solenoid is activated by the ECU, cylinder (D), magnetized by the coil winding, begins to pulse upon piloting by a duty-cycle signal: pulsing of the cylinder releases duct (B) and closes duct (C) to allow excess pressure from the turbocharger to reach wastegate actuator (6) through pipe (2) and pipe (1) and modulate the excess supply pressure.

Conversely, when cylinder (D) closes duct (B) and opens up duct (C), the pressure that previously acted on actuator (6), is drained through pipe (3) in the turbo intake duct to increase turbo pressure.

Duct A of the three-way solenoid is marked with a spot of blue paint and duct B with a spot of red paint.
In the case of service operations on this device, take great care to fit correctly, i.e.: duct A (blue spot) is connected to actuator (6); duct B (red spot) is connected to turbo pressure relief duct.

MECHANICAL BY-PASS VALVE

A by-pass between turbo low pressure pipe (intake) and high pressure pipe is responsible for deadening the characteristic compressor noise during over-run.

The vacuum set up upstream of the throttle valve acts on the by-pass valve membrane to open the valve.
The supply system downstream of the turbine is thus put into direct connection with the air cleaner and the excess pressure in the turbocharged circuit section is drained to the outside.
During this stage, a pressure peak occurs due to the sudden drop in air flow required by the system.

When the throttle valve is opened again during acceleration, the by-pass valve closes to restore normal supply circuit operation.

1. Vacuum inlet pipe
2. Superimposed pipe
3. Vacuum pipe

MAIN PRECAUTIONS TO BE OBSERVED FOR PROPER USE OF A TURBOCHARGED ENGINE

• Never run the engine without an air cleaner. This could damage the turbocharger due to the extremely high energy acquired by even the smallest foreign particle.
• Never turn off the engine at medium-high speeds before it drops to idle speed. The engine would stop too long before the turbine and thus remain without lubrication for a certain period, which would damage it. After a period of sporty driving, run for a few minutes before turning off in order to speed cooling of the turbocharger and exhaust manifold.

INTERCOOLER

The intercooler between the turbocharger and the inlet manifold cools the charge admitted to the cylinders in order to increase its weight. This ensures the engine power output during combustion is greater.