Vintage Cars: 77 450SL Cranks but wont Start, fuel distributor, auxiliary air

Question
77 450SL Cranks but won't Start

I replaced the Fuel accumulator, getting good PSI +75 PSI Main input of Fuel Distributor.

Checked pressure at each injector 45-50 PSI, injectors sprays ~48 PSI.


Have spark , checked.
WUR measure 26 OHMS.

I tried to adjust the IDle Setting NO START.

How do I test the Fuel Distributor?

I have a second Fuel Distributor that I opened and fairly easy,  I'm wondering If I can use an Ultrasonic  machine and replace the O-rings.  I do not know how to disassemble the Control Piston in the Middle of the Fuel Distributor.

How do I test the Auxiliary Air Valve?

Thanks,
Ernie

Answer
well a little more information - has the car ever started while you have had it, is this a new issue.  any recent work on the timing chain?  Are you sure the spark is getting to the right piston as the right time, any recent work to the distributor, plug wires?
If you have air, fuel at rails to injectors , spark on time and compression, the engine will run, or should.  have you checked compression?
AAV is checked off car.  Cold air should move through it freely, when hot it closes off completely