We have two hypotesis for $60.
First is $60 is at 180* or end of power stoke.
If we assume that aluminium heads run colder than iron that lines perfect. More time needed for the fuel to evaporate, since the intake valve is colder.
Also the stock settings for cold startup, also lines up. The setting is $20 which is end of intake stroke. At subzero temps of the heads and fuel, the time the fuel will evaporate is unknown, so the spray is while the intake valve is open direct in the cylinder. At this point there will be alot of unburned fuel in the exhaust, and that could be the reason for low AFRs settings at cold startup.


The max 6f could be for pcm to resyncronize the first pulse. The counter goes to zero and than starts at $80, It might need one pulse to syncronize again at $70.

We are not sure where the zero point is at also. So all of the assumptions might be wrong.
A new scope chart to confirm the settings will be great.


I know for sure that the combustion mixture must be well mixed air with evaporated fuel. Liquid fuel don`t burn well[if at all] and can wash down the oil film on the cylinder wall.
Higher fuel temperature and pressure with good spray pattern injectors can atomize fuel better, so it evaporates before hitting anything.