N57 wierd engine problems , wierd symptoms


Oct 28, 2017
Hi everyone

my wife has a f11 535 xd 2012 (tuned) and it`s now at 175 000 km /110 000 miles.

it has jerk now for 4-5 month with odd behaiviors.
it throw fault codes from engine air mass vs egr and hot film measures vs programming
start is normal but when i start to drive it has some hesitating struggles on very light
throttle until engine is warm and it throw ses light every day on dash.
if my wife jump in the car and start drive it, she get every time drivetrain error on it, i don`t know how ??

fault codes is

i did boost leak test to chargepipes and fmic, nothing problems on those.

i have done monitoring of sensor parameters and this is what i found ( don`t know if all this is normal)

air mass seems to behave logical untin it splutter (feel like misfire in a petrol engine)
changed air mass sensor, it act exactly as old one, i did reset it, not any better.

egr, egr pipe was broke, changed whole unit to new, so i assume it`s ok without
leaks. egr valve is still old, i ordered it today and will change it too.
logs on egr is acting odd, from start it shows egr% and difference to what it
should beseems logical except when difference is over 40% for over 4 sec -->ses.
but when engine warms both values drop to 0% and stays there.

lambda act almost as wierd as that egr.
cold start show logical values from 1.1 to 1.99 seiling between those depending
on throttle position and terrain (uphill or downhill) but when it warm up it start to jump between
0.998 and 1.998, not any values between those, on idle and very light throttle, it`s 1.998 and
normal driving 0,998.
lambda and egr seems to start acting wierd at about 60c engine temperature.

iat does not show any problematic values, follow logical values without any spikes, high or low
suddent jumps.

at first, i`m ihtrested on how lambda and egr should act on a car without any faults.
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