Anthony,
While I appreciate your attempt at diagnosing the problem, these facts still remain the same....
1. The engine/prop code in the Saab is very complex. We override the throttles and the props. Therefore, observing the Dataref you mentioned above is not applicable and really does not provide any diagnostic value.
2. The next update (yes, I know it's taking longer than expected) has all new manipulators and logic for most of the systems. As previously stated, we are no longer "patching" 1.5.1. So, whatever answers/conclusions you've arrived at are not going to be addressed or applicable to the next update.
Given these two facts alone, I suggest that you not put any further effort into diagnosing an old version that will not be patched and whose code is changing drastically in the next update. When the new update is released I hope you will try it out and let us know how it works for you. If you are still having problems we will be happy to work on diagnosing them against the new systems logic.
FYI... none of our internal testing of the update is producing any kind of issues with the engines not starting, with or without hardware.