It's not starved for air, it's not possible.
Check to make sure the air flow meter flap moves -- it should be open
all the way with the engine running at idle. If it sticks, it's a
problem, but otherwise not.
Verify that the EGR and turbo boost control vacuum transducers hold
vac -- if they leak, you won't get anything but "limp mode" which is
very slow. Usually not 20 mph, though. Check that the actuators for
the EGR and boost control work, as well, and that the EGR is not
sticking open. Use a MityVac and pull it open, then pull the hose
and see that it snaps fully closed instantly. Any hangup in closing
will give you fits.
Most especially check that EGR valve -- when the one on my Volvo TD
stuck, the car would produce absolutely fantastic amount of black
smoke, make very funny rattling noises, and essentially refuse to
move. Reason is that on a diesel, the EGR is open pretty much all
the way at idle, and closes down as load (not rpm) increases -- it's
there to reduce flame temperature and hence NOX emissions, and the
flame temp is highest at lean conditions. Goes down by itself at
high load (high fuel delivery rate), so if the valve sticks open, it
will idle just fine, but fall on it's face when you step on the pedal
because the much higher exhaust pressure will smother the fire, so to
speak.
This will be complicated in the 92 by the computer control of the
boost, as a failed EGR will cause the computer to dump the boost and
you can't "drive out" of the condition like you could on my old Volvo
-- once the rpm came up and the load lightened, it would run
normally, and sooner or later the valve would close by itlself.
The car behind could vanish in the smoke cloud, I kid you not. Very
serious smoke.....
If you were getting huge clouds of inky smoke and no power, check
that EGR.
I don't think you can do what I did, simply plate it off, as the
computer will dump the boost and you will be driving without a turbo.
Peter
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