Turbo Boost trouble

[PS Saab]

Please help! On first ignition cycle the Turbo has fullboost all day long as long as you don’t shut off the engine. If you shut offthe engine and while it is still warm and start it up again the turbo will onlygo to half boost. The engine must cool down for several hours and then will goto full boost again. Any insight would greatly be appreciated!

[Digger]

Welcome to the wonderful world of Saab.
You have what could be a very easy problem to find and fix, but as in all things, getting a good answer means asking a good question. The more detailed the description the better the answer. I could guess that what you are describing is normal engine and turbo operation on cold start and that you only have an operational problem after the engine has been turned off and later restarted while still warm. I could make this guess as the odds against an engine starting with the turbo in immediate full boost when cold and half boost when warm are astronomical, but not impossible and you could be describing a real turbo operational problem under the hood, or a bad gage reading.
A little more information is needed to be of any real help and best suggestion is a good visual hands on inspection of vacuum lines and mechanical movement of turbo waste gate cold and warm.

[morleyg]

Please help! On first ignition cycle the Turbo has fullboost all day long as long as you don’t shut off the engine. If you shut offthe engine and while it is still warm and start it up again the turbo will onlygo to half boost. The engine must cool down for several hours and then will goto full boost again. Any insight would greatly be appreciated!

I have exactly the same issue with my 2004 Linear Manual Transmission: New plugs, coils, and both boost sensors. No fault codes.
(This is my 4th Saab: 900 Coupe, Gen1 9-3, 9-5 and 2000 Viggen Conv.)