If my memory serves me right the Throttle switch has to be at idle to check timing.Check the adjustment.

Ok Im going to take a shot at this one having some experience with Bosch injection systems. I do remember a warm startup procedure that would retard the timing and increase idle to make up for this in order to get the O2 senser up to operating temp quickly so the computer could go into closed loop mode. GM cars of the late 80's also had this mode and to set the timing you had to ground the timing signal so the spark module would run without a timing ref signal in order to set the distributer. This warmup sequence lasted for a short time using inputs for RPM, water temp, MAP and error voltage from the O2 across the input op-amp. After the O2 output became linear the computer would return the engine to dynamic timing and adjust according to RPM, TPS temp and MAP. The whole reason for this sequence was to get the cat back to operating temp quickly under lean warm engine conditions and get the O2 senser back on track to put everything in closed loop. Cold cycle was similar but on a diffrent timer and fuel to temp map and its purpose was to get the engine and cat warm quickly so the EPA didnt get upset.

I would imagine your timing impulse senser is located at the back of the engine and uses a countdown method of determining the dynamic timing using refrences from the pickup being so many pulses per revolution from the crank with another pulse to determine #1 firing TDC and build the sequence from there. I would look for a service connector or other means in the book to put the engine into a timing check mode. Not sure how much physical room you have available for actually altering the engine timing with respect to the factory settings however I do remember making a slot in a timing pickup mounting tab in order to gain -6 degrees of retard for a somewhat radical project car running a B230 and stout turbocharger with CIS and BASIC stamp ignition control. Car ran in the mid 14's and used strain gauge pressure sense to retard ignition in relation to RPM. Worked great till he flushed the motor!

My experience with the actual physicals of the Volvo gasoline injection systems are limited as I own diesels however Volvos being simple no-BS cars I would imagine they kept that thought process as injection systems evolved (e-volvo'd?). As for the Regina system about all I can tell you is that its a 4-bit analog/digital wanna-be that relies on error voltages across comparators (741 op-amps) using fixed 1% resistors and zener refrences for cross corrections. No real A/D conversions just predetermined threshold points for correcting mixture and timing in a somewhat linear fashion. There is a processer on board but he is pretty much along for the ride and checks up on the math once in a while, a do nothing calculator. The Bosch system was a real 4-bit and later 8-bit system that had actual look-up tables along with a true spark and fuel map along with a seperate table for limp mode. Today with OBD-2 is a true 16 bit system with learning and fallbacks to keep things tightly regulated and all based on common processers such as C68xxx and x80 numeric codes. 'nuff of that.