Twinport System Opel Corsa C

The Twinport system, already in use in the Z 16 XEP DOHC-I petrol engine now also features on the two new members of the 2nd generation DOHC-0 petrol engine series, the Z 10 XEP and Z 14 XEP, albeit in modified form.

Advantages of Twinport

• Greater movement of the charge
• Combustion stabilisation
• Increase in exhaust gas recirculation rate
• Reduction in throttle losses
• Reduction in fuel consumption

Special Features

• When the Twinport system is activated (part load), combustion is stabilised because of the increased movement of the charge. Thanks to more efficient combustion, both throttle and wall heat losses can be overcompensated for by the high EGR rates, resulting in a reduction in fuel consumption.
• Advanced injection of the fuel onto the closed inlet valve
• Stratification of the charge with a richer mixture at the point of ignition at the spark plug.

Inlet Manifold with Twinport System

The structure of the inlet manifold is in principle the same for both the Z 10 XEP and Z 14 XEP engines. They only differ in length, which is tailored to the respective engine version (3-cylinder or 4-cylinder).

A vacuum unit actuates the Twinport system; the unit uses a shared actuation rod to close and open the flaps in the inlet ports.

Control Valves - Twinport System

At idle when the vehicle speed signal = 0, the control flaps of the Twinport system are closed and the system is active.

As soon as the vehicle drives away, and a driving speed signal is thus present, the control valves are opened or closed, depending on the operating point (load, engine speed).

The engine control unit gives a command to the vacuum unit which in turn closes or opens the control flaps via the actuation rod.

• Service: So as not to diagnose the Twinport system incorrectly when checking it, the following should be taken into account:

• At idle and when the driving speed signal = 0, is when the vehicle is stationary, the control flaps must be closed, the actuation rod is withdrawn and there is a vacuum at the vacuum unit diaphragm.
• When the vehicle is being started, the control flaps are opened and after a short while (a few seconds) the control flaps are closed when the vehicle is at idle and the driving speed signal = 0.

1. Control flaps opened
2. Control flaps closed

1. 1. Reverse-transfer lever
2. 2. Connection for engine wiring harness
3. 3. Vacuum hose
4. 4. Vacuum tank (engine control unit removed)

The following diagram shows the Twinport system in both activated and deactivated states.

1. Twinport system inactive with opened control flap
2. Twinport system active with closed control flap
3. 1. Control flap

Twinport Sensor

The Twinport sensor incorporated into the inlet manifold records whether the Twinport flaps are open or closed and sends this message to the engine control unit.

There, the signal of the Twinport sensor is compared with the specified setpoint position.

1. 1. Inlet manifold
2. 2. Twinport sensor
3. 3. Test connection - fuel pressure

• Service: The control flaps cannot be exchanged or replaced.