|Saab:||: : : APC Tweak/Hack : : :|
|Information on creating a Red APC.
I accept no responsibility for anything you do with this information.
This information is as compiled from various sources, including but not limited to:
: : : Redbox resistor mod
These changes don't increase performance, but rather seem to change reaction to knock.
Replace R42 with 500 Ohm Resistor
Replace R138 with 30.9K Ohm
: : : Knock LED
Pin 19 on the APC is grounded when the apc senses knock. Basicaly we want to wire an LED to this pin. In later cars, the APC receives 12v from the brake pedal switch, to cut boost during braking. Since you probably wanted to remove this feature anyway, we can kill two birds with one stone by using this wire and connector. First identify which wire goes to the APC at the brake switch, cut it free. Now at the APC end, remove the big plug from the apc, and unscrew the one screw that holds the cover on the plug. Locate the pin that the brake pedal light goes to (20 I think). I used an x-acto to free the pin from the connector, replace it in pin 19. You now have a wire from the knock pin of the apc into the cabin. Find a good 12v power source, and wire a lamp to it and the wire you cut from the brake switch. If your using a LED that's not 12v ready, wire a resistor in one side of it to keep it from blowing. 300 ohm should be sufficient. Now you know when the APC thinks you're pinging. With the car on (not running) you can get the led to blink, and the solenoid to go crazy, by tapping the knock sensor with something hard.
WARNING: Your fuel system probably can't keep up, so don't tune your car unles you know what you're doing.
I recommend at the very least a 3.0 bar fuel pressure regulator from a non-turbo. Even so, at high rpm, I belive you will be lean anywhere over 14psi or so.
Before you do anything, read what Kevin has to say about APC operation.
Kevin K's notes on Dave N's site:
|©1998-2003 Simon Shapiro|