Boost problems still....

I have a C900 T16 (Aero?)

She only boosts to between 60% and 75% of orange. I have been told that this is due to a faulty air mass meter, and that the engine is not getting enough fuel. (Bosch system) This was from a local respected saab specialist.

I am not convinced. I am pretty sure I dont have any air leaks, and a replacement second hand APC hasn't solved the problem, although more boost is available in fifth at motorway speeds.

Occasionally on startup theres a kind of "saxophone note" for about a second from somewhere forward of the drivers seat, but not always and I've never tracked it down.

I would really appreciate ideas, as although the car still goes like the clappers, it is not as quick as it should be, particullarly from 30 to

60mph.

Cheers

This sounds very unlikely. It's easy to test the hypothesis by swapping in a known good AMM - was this done?

The first thing to do is make sure your ignition system is in tip-top condition. That means plugs, leads, distributor cap, rotor arm, vac advance. If they are old, replace them. Use OEM parts only. Use the correct plugs, and gap them right.

Next it's the fuel system. Check the fuel rail pressure is correct, and make sure the fuel filter is new or at least recent.

Clean out the throttle body, and put in a new air filter.

Check for vac leaks again. Check the dump valve.

Now go through the base-boost setup procedure, setting base boost to the correct value (5.5 psi). procedure here:

I think that pretty much covers the vast majority of low-boost faults. Have I missed anything?