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Nice going on trouble shooting the wiring issues. You need to sort the turbo control operation and intake/idle systems to get to square one before you hack around with the timing to get high boost back. There is a chance that someone screwed around with the APC system before you got the car.
With timing set to 17btdc, you are 1 degree more advanced than stock. This will often cause engine knock under load BUT NOT under boost. I think this is what you experienced. The symptom is more pronounced with older engines due to carbon build up. Under boost, you will usually get knock sensor activation at full sustained boost. The result will be a boost pulsing as the wastegate is opened by the APC. This prevents the pistons from being destroyed by detonation(knock) under high boost.
When your timing was at 8 btdc, in addition to suffering off boost performance issues, you also were running a tad rich. The 3.0 FPR probably has more to do with the richer mixture than the 8 btdc timing. But the boost well into red that you used to have, was a result primarily of the lack of knock, due to timing being retarded, and secondarily due to mixture. The knock sensor was not being triggered, because it detected no knocking.
If the idle switch is clicking just off idle, it is properly adjusted OK, but you still need to confirm continuity between terminals 1 & 2 at idle.
Cleaning everything out with carb spray takes only about 30 minutes. It is a first step. Clean AIC, throttle body and APC solenoid.
The other thing you should do is verify the base boost pressure. First pull off the electrical connector on the APC solenoid up near the coil. Go for a test drive and see where the boost gauge maxes out under WOT in 3rd gear. It will usually go no higher than mid yellow. If so, your APC system is operating OK. But you still need to set base boost to about 5.5PSI with a simple pressure gauge teed into any vacuum hose downstream from the throttle. You can turn the wastegate adjusting rod in to get base boost up to 5.5psi. The spring gets weak on all classic Saabs over time and you need to reset periodically.
Have fun learning how the system works, it's very simple and clever.
posted by 68.37.183...
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