Lord_Athlon
300+ Clurb
- Joined
- May 20, 2003
- Location
- Eau Claire, WI.
Disclaimer: This is a compliation of the works of many others...Im just putting my experience and others information into an easy to use and straightforward, easy to follow guide.
The Saab APC (Automatic Performance Control) system was designed by saab to allow 900's to run a higher boost level, yet still be safe enough that even in adverse conditions the engine wouldnt go ping ping ping boom. It senses detonation, and retards boost until the knock goes away. The system consists of a knock sensor, pressure transducer, APC control unit and 3 way boost valve. What does this mean for us volvo guys? Knock sensitive electronic boost control on the cheap.
The APC box:
This is the heart of the system. It takes the signal from the pressure transducer and knock sensor and adjusts boost accordingly.
The pressure transducer:
Looks like an oil pressure transducer. Made by vdo in sweden.
The wiring harness and knock sensor:
The Solenoid Valve:
Left goes to wastegate, the middle goes to the pressure port (turbo, intake manifold etc...) and the right goes to a vacuum source before the turbo (amm to turbo pipe, kjet bellows to turbo so on and so on)
Removing the APC from a 9000t:
On a 9000T the box is located under the drivers kickpanel. To remove it you need a T20 torx, T25 and a T15 (I think).
Pop your head under the drivers kickpanel and you will see a black box. There are two torx screws holding the box to the plate, remove them and the box should slide out from its place. This is the apc box. (if the box happens to be red, you hit the jackpot).
Now remove the screws affixing this panel to the underside of the dash. Should be on the leading edge and there should be two or three of them. There is one more 10 mm bolt near the rear of the panel towards the center console, remove this bolt also. Once the panel is loose pull it down. Might take some force and you will need to snip the zipties holding the harness to this panel. Once it is removed you will see a bunch of parts. Remove the pressure transducer, and the hobbs switch. (the hobbs switch is just fun to have around. Can use it to trigger things based on boost, or if you're kjettin' it, the terminal 11 mod)
Here is the fun part. Go to the front of the car and pop the hood. Locate the intake manifold. If its not there, your job is so much easier. On the pass. side of the intake you will see a 12mm bolt. Loosen this bolt and pull out the pcv plastic thing. Now there will be 8 hose clamps and 4 rubber/silicone hoses affixing the manifold to the head. Loosen up the hose clamps and pull the intake over towards the drivers side. Once removed, you can see the knock sensor on the backside of the block. Remove it with a 12mm socket/wrench. Now follow that harness back to the firewall and feed it through. Go back under the dash, and find the harness you just pushed through. It will be going into a much larger harness. Trim back the nylon sheath/electrical tape on the harness and you will see the shielded wire going to the knock sensor. Keep the shielded wire and the wires going to the pressure transducer. Now you have the APC connector, pressure transducer, knock sensor and some wiring harness.
Go back under the hood and locate the 3 way valve. It should be up by the radiator near the ignition coil. Remove it from its bracket and snip the vacuum lines leading to it. Make sure to get the electrical connector and the pigtail.
We've gone this far, and now you are probably wondering what to do next.
Wiring up the APC:
Pin 13 is fused power. Run a wire from pin 13 to the fusebox. Fuel pump? I would keep it off of the radio circuit.
Pin 10 goes to the larger spade on the transducer (but if you followed my advice, you already have pin 10 wired up)
Pin 23 goes to the smaller spade on the transducer (again, refer to pin 10)
Pin 12 goes to the 3 way valve. Ground the other side of the valve.
Pin 5 is a ground.
Pin 25 is the rpm signal. Take it off the coil unless you have an msd box. If you have an msd box, you either need to make a tach circuit or fire a dummy coil.
Pin 19 grounds for .5 seconds when knock is detected. Use at your will. A knock-light comes to mind.
Pin 20 Goes to the brakelight. Move that pin in the connector to pin 19. That way you have a wire thats a bit more useful
There are 3 ports on the boost valve. Make sure they are hooked up correctly.
Modding and Adjusting the APC:
The Saab APC (Automatic Performance Control) system was designed by saab to allow 900's to run a higher boost level, yet still be safe enough that even in adverse conditions the engine wouldnt go ping ping ping boom. It senses detonation, and retards boost until the knock goes away. The system consists of a knock sensor, pressure transducer, APC control unit and 3 way boost valve. What does this mean for us volvo guys? Knock sensitive electronic boost control on the cheap.
The APC box:
This is the heart of the system. It takes the signal from the pressure transducer and knock sensor and adjusts boost accordingly.
The pressure transducer:
Looks like an oil pressure transducer. Made by vdo in sweden.
The wiring harness and knock sensor:
The Solenoid Valve:
Left goes to wastegate, the middle goes to the pressure port (turbo, intake manifold etc...) and the right goes to a vacuum source before the turbo (amm to turbo pipe, kjet bellows to turbo so on and so on)
Removing the APC from a 9000t:
On a 9000T the box is located under the drivers kickpanel. To remove it you need a T20 torx, T25 and a T15 (I think).
Pop your head under the drivers kickpanel and you will see a black box. There are two torx screws holding the box to the plate, remove them and the box should slide out from its place. This is the apc box. (if the box happens to be red, you hit the jackpot).
Now remove the screws affixing this panel to the underside of the dash. Should be on the leading edge and there should be two or three of them. There is one more 10 mm bolt near the rear of the panel towards the center console, remove this bolt also. Once the panel is loose pull it down. Might take some force and you will need to snip the zipties holding the harness to this panel. Once it is removed you will see a bunch of parts. Remove the pressure transducer, and the hobbs switch. (the hobbs switch is just fun to have around. Can use it to trigger things based on boost, or if you're kjettin' it, the terminal 11 mod)
Here is the fun part. Go to the front of the car and pop the hood. Locate the intake manifold. If its not there, your job is so much easier. On the pass. side of the intake you will see a 12mm bolt. Loosen this bolt and pull out the pcv plastic thing. Now there will be 8 hose clamps and 4 rubber/silicone hoses affixing the manifold to the head. Loosen up the hose clamps and pull the intake over towards the drivers side. Once removed, you can see the knock sensor on the backside of the block. Remove it with a 12mm socket/wrench. Now follow that harness back to the firewall and feed it through. Go back under the dash, and find the harness you just pushed through. It will be going into a much larger harness. Trim back the nylon sheath/electrical tape on the harness and you will see the shielded wire going to the knock sensor. Keep the shielded wire and the wires going to the pressure transducer. Now you have the APC connector, pressure transducer, knock sensor and some wiring harness.
Go back under the hood and locate the 3 way valve. It should be up by the radiator near the ignition coil. Remove it from its bracket and snip the vacuum lines leading to it. Make sure to get the electrical connector and the pigtail.
We've gone this far, and now you are probably wondering what to do next.
Wiring up the APC:
Pin 13 is fused power. Run a wire from pin 13 to the fusebox. Fuel pump? I would keep it off of the radio circuit.
Pin 10 goes to the larger spade on the transducer (but if you followed my advice, you already have pin 10 wired up)
Pin 23 goes to the smaller spade on the transducer (again, refer to pin 10)
Pin 12 goes to the 3 way valve. Ground the other side of the valve.
Pin 5 is a ground.
Pin 25 is the rpm signal. Take it off the coil unless you have an msd box. If you have an msd box, you either need to make a tach circuit or fire a dummy coil.
Pin 19 grounds for .5 seconds when knock is detected. Use at your will. A knock-light comes to mind.
Pin 20 Goes to the brakelight. Move that pin in the connector to pin 19. That way you have a wire thats a bit more useful
There are 3 ports on the boost valve. Make sure they are hooked up correctly.
Modding and Adjusting the APC:
Last edited:
.. No loom though, so i don't suppose anybody knows the order of the pin numbering system, looking at the plug ?! or how to test the pins with a multimeter to find out? i'm gonna feed it pink noise till it blinks, just for giggles 
