Timing - Retard / Knock Sensors
We will come back to the VCM Scanner and review more timing graphs in a bit, but at this time let's jump over to the VCM Editor and talk about the knock settings.
We find knock settings under two tabs:
Engine \ Spark \ Retard
Engine \ Spark \ Knock Sensors
Under the
Ratard tab we find knock limits in the form of
Knock Retard Amount and
Maximum Knock Retard vs RPM (PE) or
vs. MAP (Non-PE) It is important for us to acknowledge these but keep in mind just because the PCM can pull you in say 20 degrees to prevent engine knock that doesn't mean we can just set our Base timing willy-nilly and depend on the knock retard feature to make it right. Under this tab we also see
Recovery Rate. When we get to performance tuning this may be a setting we revisit as it tells the PCM how long to hold the retard timing before returning it to normal, staying retarded for too long can rob you of some horse power.
Think of the
Knock Sensors tab settings as the internals of the VCR (you 40 plus something year olds, lol) say you want to be an actor or a director, yes you need to know how to operate a VCR (pronounced YouTube of the 80s) but that doesn't mean you need to know how to build one, or know exactly how it works, other than we put the VHS tape in, and press Play, hewk on some machines it starts playing automatically. So for the time being just trust that the GM engineers knew what they were doing when they tuned our two knock sensors at the factory, remember this tutorial is for a stock(ish) LS engine swaps, not extreme builds. So for now we leave this tab alone, but this is where you would adjust knock sensor sensitivity.