Map423 needs the hex2dec-file from Office, you have to install this option.
After install you have to click on all lines to activate the hex2dec.

You never get a engine start with a 0 or -0 TDC degree-angle.
Only if the engine is running, the degree-angle can be 0 TDC.
Normal engine (also PUM) have a max of 5 degrees TDC on hig rpm.
Start degree-angle must be ~30 degrees.

BTW, it's dangerous to set the degree-angle on start at 0 (or -0) degrees.
It's posible the explosion will be inside your carter and blow the carter up !!
Your ports will be opened after a few degrees when the piston goes down.