Re: electronic throttle butterfly valve problem?
Have purchased one of the DTE manuals from electronicmanuals.co.uk and here is an extract of the section on the butterfly valve,
"With the engine switched off, the thgrottle is open because there is no vacuum.
With the engine running, the throttle is open because, as the Pierburg solenoid valve is not supplied, it prevents the vacuum fronm reaching the pneumatic actuator.
The vacuum accumulates in the reservoir whilst the engine is running.
Whilst the engine is being switched off (when the key is turned to the OFF position), the control unit keeps the actuator relay feed supplied for 4 or 5 seconds and, at the same time, places the Pierburg solenoid valve to earth which, on opening, sends the vacuum, whih has accumulated in the vacuum reservoir, to the pneumatic actuator which closes the butterfly interrupting the flow of air to the cylinders."
So sounds like the behaviour I have observed is perhaps normal. still don't really understand how it works! but will try and get diagnostic on the weekend.