"Anthony Cooke" <ant7t5@tiscali.co.uk> wrote in message
news:407d1dae$1_1@mk-nntp-2.news.uk.tiscali.com...
> Hello, I have just bought a 1996 9000 CS eco. It's my first Saab and I
think
> it's great.
>
> It is running fine under normal conditions but when I go to overtake 
the
> fuel cuts out as soon as the turbo kicks in. Someone has suggested that an
> APC Solenoid or control box has gone bad and is protecting the engine when
> it doesn't need to. The problem starts at around 3500 revs but only if I'm
> heavy footed.
There is a lot more to it than that...
Where is the boost gauge when the cut-out happens? Is it way up in the
middle of the red? If so, that is where the overpressure switch is supposed
to shutdown the engine by cutting spark. If it is low red or orange then
the switch may be faulty. It is mounted on the right side firewall.
The turbo is easily capable of making too much boost pressure which has to
be limited based on engine running conditions to prevent destroying the
engine. The control box (APC) has the job of monitoring engine running
conditions and sending the electrical signal to the APC solenoid. The APC
solenoid's job is to modulate the vacuum going to the wategate control
dashpot. The wastegate controls the boost pressure by dumping excess
pressure when opened.
If you were to unplug the electrical connection to the APC solenoid it
should route all of the vacuum to the wastegate dashpot and drop to "base
boost" only, which should be near the middle of the center orange section of
the boost gauge. This mode is actually quite driveable though you will have
less maximum power.
If you still get too much boost then either the APC solenoid is stuck closed
(actuated) or the wastegate is stuck closed (won't dump pressure).
I would suggest looking at this web site which goes through troubleshooting
the APC system quite well, though it may be a bit too technical for the
average handy-Joe.
http://68.18.142.57/turbo_folder/baseboostdia.htm
Good Luck,
-Fred W