Valvetronic noise (bank 2) 4.8is
 

Hi all,

Im working on my bmw e53 4.8is. It has misfires, starting at cylinder 5 and progresses to other cylinders, also from bank 1.

Today i heard noise coming from valvetronic motor on bank 2 at idle. It sounds like a bearing is almost at end of live.i took the motor off checked the shaft and bearing play, but didnt feel anything.

So far for misfire if done the following:

-changed all spark plugs
-changed all ignition coils.
-changed CCV valves
-checked MAF sensor.
-changed vacuum pump seals.
Next up, will do a smoke leak test.

Timing chain

If it's had a complete oil change due to other mechanical issues and then not pre pressurized prior to starting it could have slipped a few teeth before oil pressure builds. Possibly also caused by broken timing chain guides. Also could be failed exhaust or inlet camshaft gears on the camshafts.

That was the cause of the misfires on my N62 resulting in engine removal and complete rebuild.

Maybe remove the valve cover and check the timing using the tools

Good luck!

suddenly one day, you had a misfire, now it's all a complete engine misfire. and to troubleshoot, you started to replace everything.
keep going at that rate, you will replace the entire engine with no change.

get the INPA tools so you can check your fasta values if your timing is within tolerance, analog 2 check engine rough running. performing a smoke leak test is a good idea.
if there's no timing, compression, fuel or ignition faults, then can try running your valvetronic at maximum lift and if there's no misfiring can eliminate that system as faulty such as wear in eccentric cam/levers. you can try with tool32 and steuern_vvt if you manage to get that far ahead.

troubleshooting on these engines is complex and not straight forward. if you jump in a start replacing a lot of parts, not being able to isolate a cause will in turn make the problem worse and more complicated as you go on. it is also possible to have concurrent multiple causes of faults and they have to all progressively be isolated and corrected.