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Turbo Boost Adjustment 2.0 Liter

[Saab 900 16V-NT, 900 16V-T, 900 2.1-NT, 900 8V-NT, 900 8V-T, 9000]

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 deceleration 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

A vacuum hose about 6' long, 3.5 MM internal diameter with a vacuum T capable of connecting to one of the small vacuum hoses on the intake manifold

Pressure gauge, capable of measuring 0 - 10 PSI. and capable of plugging onto the hose in tool 1.

11 mm wrench

Small straight screw driver "pocket size"

A small Jesus pin "To insert into the safety wire hole on the turbo waste gate shaft at the adjustment point.

STEP 1 Disconnect the electrical connection at the APC valve' The valve is located on 900's on top of the radiator near the upper radiator hose 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.
STEP 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.
STEP 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 11 mm 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

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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