Control valve, VIM damper (454), Simtec
| Control valve, VIM damper (454), Simtec |
| Location |
Control valve, VIM damper (454)
| Principal use |
Regulates activation of the vacuum unit for the VIM damper.
| Type |
Electrically control solenoid valve, non-energised closed. When the valve is not energised, the port for the vacuum unit is connected with the atmosphere. When power is supplied, the port for the vacuum unit is connected with the intake manifold. The VIM damper closes so that the intake channels become long.
| Connection |
| Pin No. | Signal type | Description |
| 1 | Power supply B+ | Valve's power supply from main relay 229 |
| 2 | Control | Valve's control from ECM pin 2(A) |
To achieve a high degree of fullness (volumetric efficiency - VE) over a broad engine speed register, the length of the channels is variable - long or short.
Long channels generate good VE and thereby high torque at low rpm. At high rpm, the long intake channels provide too much restriction. The intake channels are made short in order to achieve a high VE at high engine speed.
This contributes to the engine's flat torque character - 90% or more of maximum torque over the interval 2400-5700 rpm.
A non-energised solenoid valve generates an unactuated vacuum unit and thereby short intake channels.
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