So I get in the E53 one morning and it will not start.
The Engine cranks but it will not fire. Here are the things I have done tor try and troubleshoot.

I checked for spark. I am getting a spark. It's orange, this normal? Should it be blue?

Checked fuel pressure at the rail 47 psi That's within spec.

Used a long screwdriver as a stethoscope to check for fuel injector pulse. I definitely hear the number one injector ticking while the engine is cranked.

I brought the 7 year old battery in to have it checked at advanced auto. State of health is very good according to the EXP 1200 battery tester they have there. Its putting out 12.51 volts and 620 CCA under load. It is rated at 650CA. The counter guy said he could not in good conscience sell me a new battery as this one is perfectly fine.

I disconnected the airbox and sprayed started fluid in the intake. It still would not hit.

So to recap.
I have spark
I have injector pulse
I have fuel pressure
battery tests OK

What am I missing here?

Any help is greatly appreciated.
Thanks