IIRC, you don't even get to set the timing on those engines. That's set by the lobes on a star reluctor that is pressed into the harmonic balancer and picked up by a coil in the timing pointer. So everything, and I mean EVERYTHING, is done by the computer. That is why it is necessary to pull the codes to see what the computer thinks. Everything may be ok, but if not the computer could be in limp-home mode and you will not have reasonable power. The computer knows and you need to find out.

Edit: I forgot you can turn the distributor. Duh!