Adjusting APC FAQ



FAQ provided by Thomas Townsend (saabtech@vnet.net) and Ywan Mason (ymason@bellsouth.net)
	ADJUSTING TURBO APC SAAB 900 9000 ALL 2.0 LITER MOTORS

NOTE: A good time to adjust the turbo "APC" is after a major service. At
which time all filters are clean and clear as well as fluids. It is
essential that the decell valve, evaporative canister, and any other
source of a intake manifold vacuum leak malfunction be eliminated. Also
timing and any timing control device be in working order as well as high
octane big oil company's fuel.  As follows is a step by step procedure
on adjusting the turbo into range for the APC system to function
properly. This is known as setting the base boost. The adjustments of
the pressures vary from year to year and between models and has a
tolerance of .5 psi. If you chose to adjust out side these limits you
may as well take your APC system and trash it. Crank up the boost, so
your way over there in the red. It doesn't matter if its boiled or fried
the fact is its COOKED if you go too far. There is a over boost
protection switch, if in working order that will turn the fuel pump off.
The damaging effect is out of the frequency of human hearing. APC is a
engineered control device, developed by mechanical and electrical
engineering theory to take your saab to the limits. 

	THE TOOLS:
1. A vacuum hose about 6' long, 3.5MM internal diameter with a vacuum T
capable of connecting to one of the small vacuum hoses on the intake
manifold..
2. A pressure gauge, capable of measuring 0 - 10 PSI. and capable of
plugging onto the hose in tool 1.
3. A 11mm wrench
4. A small straight screw driver pocket size
5. A extra small Jesus pin To insert into the safety wire hole on the
turbo waste gate shaft at the adjustment point.

***** PROCEDURE*****
1. DISCONNECT THE ELECTRICAL CONNECTION AT THE APC VALVE.
	A. The valve is located on 900's on top of the radiator near the
upper radiator hose and on top of the radiator and under the ignition coil
on 9000's. The valve has 3 hoses extending out of the side of it and a
connector 2 wires out of it's top.

2. Find a small vacuum hose at the intake manifold Any will do if it
has suction at idle  WITH THE EXCEPTION OF THE PCV HOSE, That is the
one with the check valve in it that goes to the valve cover and connects
at the PCV valve, with large hose under it. String the hose out the back
of the hood near the left hood hinge and into the drivers side open
window. Plug the gauge into the test hose. Close the hood, start Saab
and allow to reach operating temp.

3. Go for a test drive and do some heavy accelerating, NOTE the Max
pressure.
	IF its to low, shorten the adjustment shaft and vice versa. At the
pivot point where the waste gate shaft meets the rod there is a 11mm lock
nut. loosen it several turns.
	Use the small screw driver to pry off the C clip on the shaft after
removing the safety wire at the adjustment point. Pull the adjustment rod
down off the waste gate shaft. Screw the end in to shorten the adjustment
rod and increase boost. Sometimes it is necessary to hold the rod tight at
the waste gate valve end, to break the adjustment shaft loose from
corrosion.
	2 complete turns computes to .5 PSI + very roughly
	IF you had 5 PSI and wanted 5.5 PSI you would shorten the rod 2
turns to gain .5 PSI. Reverse the procedure to reduce pressure. After you
have made the adjustment, pull the rod over the turbo waste gate shaft.
Insert the C clip and slide the Jesus pin into the safety wire hole.
	IF the old C clip broke on removal I just leave it off, the Jesus
pin does a good job of keeping the shaft on the rod.
	Sometimes it is necessary to make this adjustment two and possibly
three times. ADJUST TOWARD THE TOP END OF THE SPECIFICATION FOR MAX
PERFORMANCE.
	IF your adjustment is too high the OVER BOOST PROTECTION SWITCH 
will kick in when you go to pass someone and turn the fuel pump off until
you return to a safe turbo pressure. This is a annoyance and can be
dangerous in traffic. IF this happens you have gone too far on the
adjustment or your APC system has a problem.

THE SPECS: ALL GARRETT TURBOS
NON APC 81- 82.5 900T = 7.5 - 8 (PSI)
APC 82.5 - 84 = 4.41 - 4.85 (PSI) I HAVE SET TO 5 - 5.5 (PSI) = OK
APC 85 - = 5 - 5.5 (PSI)

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