Intake Manifold Module
The X 18 XE1 DOHC petrol engine has an intake manifold module with switchable intake pipe lengths, just like the X 20 XEV.
The fuel pressure regulator is not installed on the fuel distributor pipe, as is customary, but is a component of the fuel tank module because the fuel system has no return.
The composite-construction engine control unit is secured directly on the intake manifold module.
The intake manifold module comprises the following components:
- Engine wiring harness with injector plug strip
- Fuel distributor pipe with service valve
- Injection valves
- Throttle valve adjuster
- Switchover valves for solenoid valve
- Switchover valves for vacuum unit
- Engine control unit
Operation of Switchover Intake System
There is a switchover valve (1) for every cylinder on the shaft that is fitted in the intake manifold module. The switchover valves are controlled as a function of the engine speed and the load of a characteristic stored in the engine control unit. The switchover valves are always open above a certain engine speed (II), and this results in an optimum torque characteristic particularly in the lower speed range.
- long intake path (switchover valve closed)
- short intake path (switchover valve open)
- Switchover valve