I am trying to track down an issue My 1994 BMW 530it is stumbling at 5500 rpms and full throttle This just started a couple of days
The car ideas smooth and drives normally except for full throttle at around 5500rpms What I have done so far: -Changed fuel filter -Made sure oil level is correct since oil pressure controls the Vanos
What I am doing next: -checking the coil packs -Checking voltage at the coil packs
Any ideas of what this could be?
I had a customer car doing the same thing, ended up being the crank pulley. edit the car was also a 530 automatic.
The crank pulley has a trigger wheel built into it, the pulley is also rubber damped in typical crank pulley fashion.
The rubber can lose it's bond to the outer/inner sections of the pulley which will cause weird crank position sensor readings and misfires.
In the case I saw the problem was intermittent but became worse over the course of several days of test driving/trouble shooting.
I got lucky and happened to notice the crank pulley wobbling, replaced it with a used unit and the misfire went away.
Plugs, wires other ignition parts. Could be going lean at high rpm.
vazbmw wrote: This just started a couple of days The car ideas smooth and drives normally except for full throttle at around 5500rpms
Well if it started a couple of days, your car is likely causing a rift in the space/time continuum and you won't pass emissions that way 
Well since the car is ideaing smooth up to 5500, the CPU (Creative Power Unit) might not be getting enough power
OK seriously it's probably an ignition timing problem. Try getting the car above 5krpm using the least amount of throttle possible and see if it runs any different. If so, it might be a fuel delivery problem.
Good info Sounds exactly like my symptoms. I did also notice my splug connector had evidence of lots of arcing, pluys 4 of them smelled burnt I put some dielectric grease on them to see if I could stop the arcing. It stopped for about 15 and started again
ansonivan wrote: I had a customer car doing the same thing, ended up being the crank pulley. *edit* the car was also a 530 automatic. The crank pulley has a trigger wheel built into it, the pulley is also rubber damped in typical crank pulley fashion. The rubber can lose it's bond to the outer/inner sections of the pulley which will cause weird crank position sensor readings and misfires. In the case I saw the problem was intermittent but became worse over the course of several days of test driving/trouble shooting. I got lucky and happened to notice the crank pulley wobbling, replaced it with a used unit and the misfire went away.
Once I break the 5500 rpm mark It is somewhat ok, but I can tell power is down. It doesn't rip through the rev range like it normally does
I am now focusing on ignition One coil's resistance is out of spec and the splug connector issue. So this looks like the obvious place for potential problem
The balance will be looked at too I remove that a few months ago to change a water pump, So I better see if it is loose
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