N55 Crank No Start

_Mars98_ · 10-15-2023, 05:03 PM

Hi guys,

Just finished rebuilding my whole engine after a spun bearing, all the mechanical parts went pretty well and managed to get the engine back in the car and all connected up no problem. Got the car started and it was running a bit rough but was mostly okay, however after 10 mins a squealing noise started from the lower engine and crankcase pressure was way higher than it should be, I had changed the PCV valve on the rocker cover while the engine was out so decided to just get a whole new rocker cover to go with the rebuild.

Installed the new rocker cover and reset the valvetronic limit positions and all adaptations, however the car would now only start for a second or two and then backfire and cut out throwing codes for the exhaust cam timing, changed the exhaust cam vanos adjuster and both solenoids and re-timed the engine perfectly, unfortunately the car would still start, backfire and die.

My next thought was to pull the MHD stage 2+ map off it and put it back to stock thinking maybe the adaptation reset isn't playing well with the tune, however now it just cranks and doesn't start at all (does sound like it wants to at points but never quite manages it)

There are no codes that look concerning to me (a few that have been there for years including FlexRay Initialisation and wrong steering wheel etc) and the compression test came back spot on in every cylinder.

I did think it maybe had something to do with fuel however it did start and run immediately before I changed the rocker cover and reset adaptations.

Does anybody have any useful insights that might explain this at all, I've double checked all electrical connectors and grounds and am genuinely running out of ideas here.

Here's a video of it as it stands just now:

Please let me know if I'm missing something totally obvious

_Mars98_ · 10-16-2023, 05:05 PM

UPDATE

Fuel rail pressure as it should be on crank so swapped the old plugs back in and the car now starts and runs (although very rough with misfire codes (140010 combustion misfire - several cylinders)

10-15-2023, 05:03 PM	#1
_Mars98_ New Member 0 Rep 6 Posts Drives: BMW M135i F20 Join Date: Jul 2023 Location: Glasgow iTrader: (0)	N55 Crank No Start Hi guys, Just finished rebuilding my whole engine after a spun bearing, all the mechanical parts went pretty well and managed to get the engine back in the car and all connected up no problem. Got the car started and it was running a bit rough but was mostly okay, however after 10 mins a squealing noise started from the lower engine and crankcase pressure was way higher than it should be, I had changed the PCV valve on the rocker cover while the engine was out so decided to just get a whole new rocker cover to go with the rebuild. Installed the new rocker cover and reset the valvetronic limit positions and all adaptations, however the car would now only start for a second or two and then backfire and cut out throwing codes for the exhaust cam timing, changed the exhaust cam vanos adjuster and both solenoids and re-timed the engine perfectly, unfortunately the car would still start, backfire and die. My next thought was to pull the MHD stage 2+ map off it and put it back to stock thinking maybe the adaptation reset isn't playing well with the tune, however now it just cranks and doesn't start at all (does sound like it wants to at points but never quite manages it) There are no codes that look concerning to me (a few that have been there for years including FlexRay Initialisation and wrong steering wheel etc) and the compression test came back spot on in every cylinder. I did think it maybe had something to do with fuel however it did start and run immediately before I changed the rocker cover and reset adaptations. Does anybody have any useful insights that might explain this at all, I've double checked all electrical connectors and grounds and am genuinely running out of ideas here. Here's a video of it as it stands just now: Please let me know if I'm missing something totally obvious
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10-16-2023, 05:05 PM	#2
_Mars98_ New Member 0 Rep 6 Posts Drives: BMW M135i F20 Join Date: Jul 2023 Location: Glasgow iTrader: (0)	UPDATE Fuel rail pressure as it should be on crank so swapped the old plugs back in and the car now starts and runs (although very rough with misfire codes (140010 combustion misfire - several cylinders)
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