2011 128i N51 Crank no start issue

[BimmerxVision]

Hello all, I’m scratching my head with an issue that I can’t seem to resolve. First let me list what has already been checked and replaced. Replaced low pressure and high pressure fuel pumps (OEM), spark plugs ngk iridium (gapped to spec). Replaced coils Bosch (OEM), Replaced air intake filter (K&N), replaced fusible Link (OEM) replaced radiator (OEM), Replaced valve cover and gasket (OEM), Replaced eccentric shaft Sensor and seal (OEM), replaced fluids everything OEM recommended except for Oil I use AMSOIL products for oil changes and filters. Checked all fuses and replaced with new ones. Replaced ignition Harness (OEM). Replaced MAF Sensor (OEM), I’ve checked the ECU for any water damage and all the prongs still look healthy and new, I bought the car used and drove it for over a year with no issues, I’m a stickler for maintenance so I’ve kept up on my recommended mileage maintenance schedule the only thing I haven’t looked at is my VANOS acuators. One day I experienced some misfires and rough idle, I proceeded to diagnose the issue and pulled codes with a Bosch scanner. Found only misfire codes for 3 of the 6 cylinders, this was an intermittent issue but bothered me to no end, I ordered up some
New spark plugs and coils I use FCP Euro and Pelican Parts for everything. I replaced the coils and plugs and the car ran fine for about another week after clearing the codes and replacing parts. The issue then came back, I figured maybe just a bad batch of coils so I ordered some
More and replaced them, ran fine no issue. 1 month later it happened again, I decided to have my injectors cleaned and flow tested and changed my air filter, injectors passed inspection and I replaced the seals, the issue still persisted and I got some new codes on different cylinders this time, as well as the MAF Sensor and the EAC Sensor radiator, I replaced both the MAF Sensor and radiator. The issue still persists, I take the 1 series to my buddies shop as he is a reputable BMW mechanic and does good work, I requested a compression test and boroscope fearing the worst. My buddy checked it out and the engine came back healthy on the compression test and the boroscope indicated no damage to any cylinders. He replaced some coils with spares he had around from an engine swap and the car ran fine, I drove the car back home from
The shop and the issue began again, I decided I wanted to replace the fuel pumps and the ignition harness. Replaced the fuel pump and the car runs but still misfires, I then proceed to replace my valve cover and gaskets while waiting for the harness to ship to me. I replaced them and the car ran awesome, no hesitation, misfires or rough idle. I received my ignition harness a week later and replaced it because I couldn’t stand the sight of the old one it was rough looking and I had a feeling it was time to replace it, I swapped it out and now the car will crank but won’t start, new battery and fully charged, can someone please help
Me with this issue? Does the harness need to be registered? Is there anything I should be looking for?

[BimmerxVision]

I also replaced my o2 sensors and all my fuses just to be on the safe side.

[Blau]

My first thought was battery. Batteries on this car make it do crazy shit.

Check the red battery power distribution box. You might have missed one of the connectors or it may have shorted out when you were back there.

Also check your ground straps. There are two, one on the driver's side near the steering column and one on the passenger side near the back of the motor near the exhaust manifold.

Best of luck.

[BimmerxVision]

Originally Posted by Blau

My first thought was battery. Batteries on this car make it do crazy shit.

Check the red battery power distribution box. You might have missed one of the connectors or it may have shorted out when you were back there.

Also check your ground straps. There are two, one on the driver's side near the steering column and one on the passenger side near the back of the motor near the exhaust manifold.

Best of luck.

I swapped out the red battery power distribution box (fusible link) with a new one , I unplugged and swapped with the new part exactly as it was before. Do you have a picture for reference perhaps? The earthing wire is interesting though I’ll have to check those out and get back to you.

[Blau]

Originally Posted by BimmerxVision

I swapped out the red battery power distribution box (fusible link) with a new one , I unplugged and swapped with the new part exactly as it was before. Do you have a picture for reference perhaps? The earthing wire is interesting though I’ll have to check those out and get back to you.

That's the one I was talking about. Last thing I can think of is the little power junction at the back of the engine bay. That's were the positive cable comes in from the battery. Check to see if there is a loose or severed wire. Other than that I'm stumped too. Best of luck.

[BimmerxVision]

UPDATE! Got the car to start, it was the ignition harness connector that plugs Into the DME, Car starts and runs great, one concern I have is extended cranking time or multiple cranks to start, I’m not sure how long it will take the DME to relearn everything I reset all adaptations and cleared all codes stored in memory. Any suggestions on extended cranking troubleshooting? I will repost this question in its own thread as well.