Ford Workshop Service and Repair Manuals

Swirl valves are located inside the plastic intake manifold which close off one of the two intake ports both in stratified operation and partially in homogeneous operation (at engine speeds below a certain threshold).

This produces the required swirling of the air, which helps to form the ideal mixture of the injected mixture cloud in stratified mode (this means that the motion of the air assists the formation of the mixture).

The swirl valves are opened and closed by means of a positioning motor which is actuated accordingly by the Powertrain Control Module (PCM).

The position of the swirl valves is monitored by a position sensor which is coupled directly to the swirl valve shaft.

In stratified mode, the swirl valves are opened continuously within a limited range according to requirements as the engine speed increases.

In homogeneous mode the swirl valves are also completely closed up to a certain threshold engine speed (below approx. 3000 rev/min, except under full or near-full engine loads).

A total of four rubber gaskets are used to provide the seal between the intake manifold and the cylinder head.

These rubber gaskets must be checked for damage during service, and changed if necessary.

The recirculated exhaust gas is evenly distributed through the connecting pipe (integrated in the intake manifold) to all cylinders.

The intake manifold must not be dismantled. It must be replaced as a complete unit in the event of service repairs.

The position of the swirl valves plays a key role in determining the movement of the charge. Closing the swirl valves results in a circular motion of the charge around the vertical axis in the combustion chamber.

The corresponding increase in motion of the charge enables the mixture formation to be optimised.

As the closed intake port represents a restriction, it is opened up under high air mass flow (i.e. under full-load operation).

In addition to the air charge in the combustion chamber, the position of the swirl valves also has an influence on the ignition and the pulsations in the intake manifold.

Incorrect positioning of the swirl valves can therefore lead to misfiring. As a result, this system is relevant to exhaust emissions and is therefore subject to the European on-board diagnosis.