After a very aggressive romp home today I noticed the car surging at idle. I turn the car off and restart and it's gone.
I've recently replaced the plugs and coils with the OE parts (newer Delphi coils BMW now recommends) and changed my idler pulley, tensioner and accessory belt just the other day. Neither of those was related, but was just done on the normal maintenance schedule.
I did recently pull both Vanos solenoids and blow them out/clean them, but if it was them I would have expected a code. I usually clean them every 15-20k miles.
Wonder if anyone has any idea of where to start looking. Not a single code.
Wondering if this may be a malfunctioning DISA unit, but I'd hate to replace them without knowing for sure. I've cleaned the MAF with MAF cleaner as a precaution, and haven't had it out yet for a good hard run since, thought I'd see what you all thought.
Here's what it sounds like when it does happen. I had just been out thrashing on it.