need to try and understand the boost system on a scooby the boost solenoid bleeds of air to allow extra boost which gets its signal from ecu so what else tells the ecu to start opening solenoid as mine will run fine without solenoid connected at 0.5 bar when i connect up it overboosts i have replaced all vacuum hoses to solenoid and turbo and left pipe with restrictor in

 

Have you tried another solenoid?

What size is the restrictor in the pipework?

 

yes tried another solenoid and brought new restrictor from subaru

 

The boost solenoid, in its normal "power off" state is closed, in which state all the air bled out of the compressor outlet via the restrictor will reach the wastegate actuator.

When the ECU switches the solenoid on, it will open up, allowing bleed air to run out of the return line back into the inlet tract, thereby keeping the wastegate shut and allowing boost to be developed beyond actuator pressure.

By the sound of things you have already done most of the obvious things in a process of elimination. If it's still overboosting, it's high time to bite the bullet and get your car in front of someone who can log what the ECU is doing. By doing so it should be pretty quick and easy to pin down the cause of the problem.

Incidentally Phill, I've mentioned this to you nicely before and you've failed to take any notice so now I'll do so a little more firmly. You care causing yourself a significant problem in dribbling this issue across several different threads. It makes it very difficult for anyone with an intent to help you fully understand what is going on and what you've done to date.

Many people just picking up on this won't even realise that you've been posting about this for a while, and the ones that do have probably got something better to do with their lives than search for the variety of different threads you've started and try to collate the information into some chronological sense - I know I can't.

It is in your best interests to put all the info in one place as it allows everyone the opportunity to simply scroll up and see what the score is, thereby preventing them wasting both their time and yours by asking questions you've already answered (see Rich's post above for an example).

If I were you I'd message one of the mods and ask nicely if they'll merge the separate discussions into one.