[Simon6666]

Hi Guys,


I need your advice please, after more than 1 year of diagnosis and part-changes of my N63 Engine (408 HP Version -new engine in 2016 current km= 100.000).

The engine is starting to slightly shudder when it is hot and in higher gears with low RPM.
-No problems when the engine is cold
-No problems when the engine is in sport mode


I have already exchanged so many parts without success, that I am feeling (I am!) an idiot!

-Coils
-Spark plugs
-Air mass sensors
-Lambda Probe before Catalytic converters
-Lambda Probe after Catalytic converters
-No fault codes in ISTA
-No errors with ABL misfire detection
-No engine leaks
-New Torque converter
-Injector Cyl. 8
-Emission test on both banks
-Timing Chain is ok
-New Crankshaft Position Sensor
-New Vanos Solenoids


The smooth-running values in idle are bad (from my point of view for all injectors, but the car does not shudder until it is hot and driven in high gears with low rpm and only just a little acceleration.
Do you have any idea what I can do next?

Thanks a lot for your help!

[Thecastle]

I'd look for leaks in your intake. Probably a leaking vent pipe and or bad filtered air ducts. This wont throw a code, but caused rough running for me. It'll show up in your fuel trims indicating unmetered air entering the system. But you can see it with a smoke test. Here are the parts, its not a bad diy. These go bad all the time and caused rough running for me, but throwing parts at a problem isn't a substitution for diagnostics. Clearly I'd take it to a new person for diagnostics.

11-15-8-647-961
13-71-7-577-451
13-71-7-577-452
11158647299

Next up would be bad pneumatic pressure converters for the turbos.

This is assuming you've ruled out bad plugs and coil packs

Then injectors

Then bad grounds

etc.

I've owned 3 BMW v8s, and these are the common issues that cause your concern.