I need your help
At the start of the month I bought a bmw. I am not a car guy,I fell in love with the car from my dad 523iA from 1997 and wanted the same car.I knew what I was getting into as the seller was really transparent.But a friend of my dad says it's no big deal and I should get it.I bought it as it was in really good condition and had parking sensors and was cheaper than most e39s.The first owner had it for 20 years and has all services documented,then the second owner had it for 3 years and had it sitting for 6 months before I bought it.The car is German. Did I fucked up or not?I hope you save me guys😭😭
Car:
2003 BMW 520i (E39) manual with BMW M54 engine
176k km
Symptoms:
Cold start misfires on cylinders 2 and 6
Shakes heavily when cold
Cold idle starts around 900 RPM then drops to ~700 RPM
If restarted warm, problem disappears
No ticking
No knocking
No overheating
Good power when warm
Sometimes slight whining noise under acceleration when warm
Fault codes:
Misfire cylinder 2
Misfire cylinder 6
Already replaced by previous owner:
VANOS
Valve cover gasket
Spark plugs
NGK ignition coils
Intake boot
CCV / crankcase ventilation system
Previous owner’s theory:
Possibly clogged hydraulic lifters ( hydraulic valve lifters)
Or oil passages/VANOS-related issue where cold thick oil causes problems until warm
Questions:
Could this still be vacuum leak / injector / MAF related even after those parts were replaced?
Could hydraulic lifters or oil pressure behavior cause cold-only misfires on cylinders 2 and 6?
What would you check next on an M54 with these symptoms?
Edit:The mechanic did a pressure test on the cylinders and he said that the pressure is good