Dangerous codes, engine shakes for only a minute on cold start, help please!
 

Thanks in advance!

Car:

2008 bmw 535i lci n54 engine sport pkg in FL (temperature)

Codes:

Misfire all 6 cylinders

O2 sensors and heat monitors

EVAP

Purge Flow

Cats

Symptoms:

Engine shakes concerningly for a minute on every cold start and lifters/valve chain is loud. Worst at noon after 15 minute drive and 4 hours sitting, so heat soak makes me think leaky injector. Kind of 'snaps' into place and smooths out and quiets down in about 60 to 90 seconds all of a sudden. Only cold starts, problem is gone if operating temp. No check engine light, no limp mode. At operating temp, Sometimes the idle rocks the car and sometimes it bounces the rpm from 600 to 900 back and forth, but only sometimes

Context:

Occured after I changed oil cooler and filter housing gasket and bleed and flushed coolant (zero experience, didnt use battery charger even though DIY videos recommended to) and injector and fuel treatment

Ruled out:

Spark plugs, walnut blast/carbon/, valve cover gasket leak

Suspects:

1. Leaky injector(s)





2. Battery, IBS or DMB (battery good under load and alternator voltage, low 12.3 standing voltage)





3. PCV system





4. Coils





5. Vanos or Eccentric cam sensor





6. Thermostat





7. HPFP, LPFP, fuel pressure regulator





8. vaccum leak (horrible wastegate)





9. Motor mount





10. Air/fuel sensor





11. Foreign object in engine



Can yall help me rule anything out?

Thanks!

If misfires are on all injectors doubt if they are all leaking all of a sudden, also battery seems ok.
First I’d do a vacuum test (smoke test or what). Maybe a vacuum leak or fuel delivery problem.
Any of the sensor you have listed should throw their own codes.

Am not to familiar with the 535 but I am chasing random misfires on my 545 only in winters though....
HTH