I have yet to actually deal with cam timing myself. I can punch up a theory, but certainly cannot verify if it is correct. So, let me tip back another bourbon and see what I can think up.
Let's assume your base cam timing is correct.
If it were to, for whatever reason retard, then the valve actuation would occur later than it should. As such, the intake valve will open well after the piston has started it's downward stroke, which will result in the cylinder underfilling with fuel/air mix which will result in a huge reduction in power. The piston will also be travelling on it's upward stroke before the exhaust valve opens which is going to create a ton of resistance against it. By the time the valve does open, there is so much pressure and volume built up against it that the exhaust cannot fully be expelled from the cylinder. This issue could be significantly reduced, maybe even taken advantage of, by larger exhaust port volume and free-flowing exhaust. Assuming however a stock setup, there is no way the system can deal with this situation. In other words, the exhaust cannot be fully expelled which will result in it getting left behind in the cylinder and mixing with the incoming fuel/air mixture. And as we all know, exhaust doesn't combust very well.
Now, if your timing were to advance, then pretty much the opposite will occur. The intake valve will open while the piston is still finishing the exhaust stroke; in other words, travelling upwards. Because of the lack of vacuum, this is going to create huge backpressure/turbulence within the intake stream which will slow it down and by the time the piston travels downwards on it's intake stroke, the incoming airflow will be too late to pick up the strength in order to completely fill the cylinder, unless of course the intake valves/ports are very fat. Concerning the exhaust side, the exhaust valve will open while the piston is still travelling downwards during it's combustion stroke. This is going to create a vacuum in the exhaust side which will cause the cylinder to re-fill with air via the exhaust system when it should be trying to clear itself! This extra volume, combined with the exhaust, will generate massive pressure at the exhaust side and once again, if the port volume is inadequate will result in exhaust getting left behind which will dilute the fuel/air mixture. Also once again, certain induction/exhaust profiles can take advantage of this, but not the stock stuff.
I'm sure that I'm missing some little things on this but the way that I see it is that if an engine has jumped timing a little then it will still run but will run like ****. If said engine is an interference design then jumped timing will probably result in bent valves. Fortunately for us, our engines are of the non-interference design but hey, I sure ain't gonna bet my engine that it won't twerk valves if the timing is off enough!
TL;DR, unless you've jumped multiple teeth which on our stock engines shouldn't happen unless the chain is pretty badly stretched (have you heard rattling sounds from the front of the engine?) your engine should run even if it's jumped timing one or two teeth.
Jumping tangents and as a bit of curiosity, would a failed crank position sensor set a CEL?
