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Bill,
I don't think detonation is mitigated by spark energy and the coil only supplies the required voltage to jump the gap. The stock CDI has more than the required voltage. I have run 28 degrees of timing on an SC, but you need to watch for detonation.
Ok, if you are new to lambda CIS on a 911, here is the super condensed, almost incorrect, but necessary way to think about it. It is a basic CIS system that is calibrated too lean everywhere, that uses the FV the richen up the mixture everywhere, using a default FV pulse open loop and above 35% throttle and the O2 sensor feedback loop below 35% throttle. If the ECU loses power and/or the FV stays closed, it is too lean everywhere and it cannot be correctly adjusted out. If your pressures were in spec and the FV was closed it would run like crap. In other words, the limp home settings are just the opposite of what you would expect from BOSCH, too lean, but at least it limps with a failed ECU. Also when reading duty cycle, higher is richer when in open loop, but high is leaner in closed loop. This is because in closed loop, you are looking at the systems reaction to the O2 reading, a high reading means the system is trying to adjust a too lean condition. For a richer open loop WOT mixture, you want a lower closed loop duty cycle. OK ?
The original cold control pressure spec was 1.4-1.8 bar at 10C rising to 3.4-3.8 bar at 40C (2.2 bar is around 20C). Warm pressure should be 3.4-3.8 bar, do you have that ? System pressure is 4.5 -5.2 bar. Have you tested how quickly your control pressure rises against temperature ?
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Paul
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