first order would be to verify if the injectors are getting constant power when the ignition is keyed on.

Then test then with an LED for pulsing as the engine cranks.

Similarly check the coil packs. Just like our Dr Bert had this problem on his W210, which was pointing to the failed master relay junction - as a member of this forum told him to check.

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2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)