Editing Openai/6940b2df-db80-8003-b707-4cc5cbedf6d9 (section)

=== Assistant: Excellent — these last photos let me close the loop cleanly. ===
Excellent — these last photos let me close the loop cleanly. I’ll be precise, grounded, and practical, because you’re now at the point where one small decision determines whether this fix lasts 10 years or fails again in weeks.

==== ### ====

From all angles you provided:
* Correct E90 A46 rear power distribution box
* Correct fusible-link architecture
* Correct mounting bracket and orientation
* Studs and aluminum bus bars are straight and intact
* No heat deformation
* No cracking
* No corrosion

So the part you bought is not the problem. It’s a solid replacement.

==== Now the hard truth, backed by your photos. ====

===== Your close-ups show all three of these failure indicators: =====
# Ovalized / wallowed-out lug hole - The hole is no longer round - That means it cannot clamp evenly
# Evidence of arcing and micro-movement - Aluminum face is scuffed and heat-polished - That only happens when the lug moves under load
# Deformed insulating lip - The black rubber/plastic around the lug is distorted - That confirms prolonged heat, not a one-time event

This lug will not sit flat on the new A46 stud — even if you torque it correctly.

: 

That’s not opinion — that’s physics.

==== You have two correct options. Anything else is a gamble. ====

===== - Have a proper high-current copper lug crimped =====
* Hydraulic crimp, not a hammer crimp
* Lug hole must match stud diameter exactly
* Heat-shrink rated for automotive battery cables

This restores:
* Full contact area
* Proper torque retention
* Long-term thermal stability

This is the BMW-correct repair.

===== Only if replacement is delayed: =====
* Lug face can be lightly dressed flat
* Hole must be perfectly round
* No copper strands exposed
* Lug must sit 100% flush
* Torque exactly 15 Nm, no more

Even then, I would treat this as temporary, not permanent.

==== - ❌ Do not stack washers ====
* ❌ Do not “tighten more” to compensate
* ❌ Do not reuse that lug if it rocks even slightly
* ❌ Do not reinstall aftermarket wires on A46

==== - The replacement box stud pocket is intentionally oval — that’s normal ====
* The lug must provide the flat surface, not the housing
* The yellow 15 Nm marking you showed is correct — obey it
* The mounting bracket and red safety covers are all correct

Nothing is missing from the new part.

==== You had: ====
* ~11.4 V with ignition ON
* Very fast crank
* No start
* Heat damage at A46

That exact pattern happens when:
* Starter still gets current
* DME, coils, injectors see voltage sag
* CAS authorizes crank but combustion never stabilizes

This is classic E9x rear power feed failure, and your photos prove it.

==== If this were on my own E90: ====

👉 I would not install that new A46 until the main positive cable lug is corrected.
👉 I would fix the cable once, correctly, and never touch this area again.

You’re already 90% of the way there. Don’t let a damaged lug sabotage the repair.

==== - Selecting the correct lug size for the cable ====
* Determining whether your cable gauge is reusable
* How to measure stud diameter correctly
* How to reroute/remove the aftermarket wires safely
* Post-install ISTA voltage and DME wake-up verification

Tell me which direction you want to go — cable repair or full replacement — and we’ll finish this the right way.