[haty]

hi guys ...i have a relative with an f10 535i , he is having many problems lately.
the car on heavy load cuts out and goes to limp mode(drivetrain error on navi) .
ista gave back misfire on cylinder 4 and air mass not plausible ,and second time air mass too high.

the mechanic changed all 6 injectors and the 6 ignition coils .....and found a tuning box on the car ..removed it but still runs the same.
the turbo seems ok. 


what you suggest ?

[Node]

Frankly - find a better mechanic There are tests one can do to check various things on a car before blinding replacing them.

[haty]

yes i know ....he lives very far from me so i can not help doing diagnostics......i suppose it's high pressure fuel pump...cause on full throttle goes always in limp mode

[RocketSurgeon]

Diagnosing from a distance is always difficult. Does he have ISTA? I would want to verify that the injectors were coded properly, check again for BMW diagnostic codes, then do data logging while he replicates the issue.
HPFP issues are not common on the N55, and I would expect to see a code if that were the problem. The air mass not plausible could indicate a bad MAF sensor, though I would also want to smoke test for leaks.
Data logging would help to diagnose a fuel pump or MAF issue.
It might be worth checking spark plugs and gap.

[willisodhiambo]

Airmass too high might mean the dme is injecting what it thinks should match air as measured by MAF but O2 sensors reporting lean mix!! Thus system reports it is getting too much air compared to what the meter (MAF) is telling it.

So the problem is a lean condition in the exhaust gases so possible issues
1. Inaccurate MAF
2. Air leak
3. Worn valvetronic shaft
4. Inaccurate O2 sensors
5. worn injectors (unlikely because when they wear they fuel too much, not too little)

You need to read the lambdas at idle and lambda adaptations to see what the O2 sensors are reporting then move on from there.

[larshutten]

You might want to take a look at the intake valves. It’s common to build up carbon on the valves.

[gyrfalcon]

implausible or too high error of mass air sensor are same errors which indicate a malfunction in n55 management mevd172y as it compares the air measured by sensor with calculated by throttle valve and to somehow valvetronic.from here you should start

[haty]

ok ..will report back with the progress