Got a strange riddle for you !
My ’96 CSE 2.3 had developed a sort of whistling noise under hard boost which started around about the time the head gasket went (although not related).
The head gasket was replaced and all was well (apart from whistle) car was boosting nicely dawes device was/is working a treat (but turned down when head gasket went and not turned back up yet) but boosting about a ¼ into the red.
This weekend I decided to investigate things and discovered that my dump valve is playing up (new one on order) but not that bad as to affect the boost.
I also discovered that the rubber pipe from the intercooler output to the ally pipe was leaking.
So I took all the pipes from the intercooler to the manifold off and cleaned them inside and out so that I could get a better seal.
I figured that the garage had taken them off to do the gasket and not cleaned the surfaces before putting it all back together.
Once done I put it all back together and got a nice clean seal.
The whistle has sort of gone, I think it was a combination of the DV and air leaking out of the pipe.
Took the car out for a spin and I now have less boost (noticeably slower) only boost’s into the mid yellow area.
I can’t quite figure it out – I should have more boost with no leak ? As the Dawes device runs off the MAP and so does the boost gauge, they should be reading / doing the same thing.
Any ideas ??