Just after thoughts to what people think of some advice i got from local saab garage (not dealer - private specalist uk). The check valve (oneway valve) that sits on the breather hose from the inlet manifold and the cam cover, apparently is of no use and does not matter if it is there or not. They removed it and didnt replace it. This was some time ago and i never noticed a difference, however i have known for a while the dump valve needed replacing and when i did replace it last week with a bosch standard dump valve I started having problems. The check engine light flickers when i come off boost quickly. Also replaced all old crummy vacuum hoses with nice new silicon ones *bling*. My idea was that the extra boost that the new dump valve was not leaking might be finding its way into the top of the engine and causing the warning light flicker. This probably exposes me as a rank amateur with no true idea about my engine but you've got to learn somehow!
so should i refit a check valve and could this solve this problem. if not any other more ideas?
Thanks Derek
PS the garage has just gone bust its a shame the mechanics were nice and helpful.