[normalguy]

Hey guys, returning BMW owner here, I haven't owned one since my 87 E30.
Just picked up a 2007 E92 335i. Car has down pipes and JB4 on MAP 5.
Car was running great then started surging upon acceleration.

YES, I did search. I did find the threads that suggest the usual walnut blast, HPFP, VANOS or any other multiple and many known issues with this car.
Car had walnut blast done recently.
Car has a new HPFP.
I could do a VANOS solenoid clean but that does not explain the following codes.
The thing that bothers me is that when I search the codes that I'm getting I get nothing that I can really understand online. I don't find posts with others that have these codes together.

The JB4 reads out:
2DEB Power management, vehicle wiring system control
2E8B Intelligent battery sensor, signal
2DEC Power management, battery control

I clear codes, car runs great. 5 minutes later car runs like garbage with constant surging when accelerator is applied throughout the RPM band.

I hope to get some honest suggestions because I love this car but I'm perplexed. Hopefully without putting preconceived notions into anyone's head, I believe maybe it is the battery??? maybe the alternator???
Why would these codes cause the car to run poorly? Are they two separate issues?

Anyways, I appreciate anyone's help. I just did the oil and filter tonight and doing new Bosch plugs in the morning.

I'll be paying stealership prices by Wednesday if I cant figure this out.

[sp1tfire]

I would place my bet on Intelligent battery sensor.
Check the alternator voltage with everything running, google it, output has to be 14.XX volts, don't recall exact number.
Stop by AutoZone - let them check the battery
Then maybe there is way to check IBS, no idea.
Whichever is the origin of your problem, voltage definitely can cause rough idle.
I don't see how carbon deposits or vanos could cause this, entirely different systems.

[normalguy]

UPDATE:
The problem was the IBS (Intelligent Battery Sensor) and a bad battery. I don't know if they both went bad or if one caused the other to go bad but the IBS tested bad and the battery would not recharge or hold a charge.
My rough idle and surging upon acceleration was solved by battery and IBS replacement. Battery cost me $190 and IBS was $390 plus labor. Everything was a $730 repair...

I went to an Interstate store and they could not perform a load test but did check voltage.
Battery was at 12.2 while car was off (insufficient).
Measurement was 14.3 at idle (alternator was good).

I purchased an interstate battery from an interstate dealer and when it was installed by my shop, they found it to be 2/3 discharged. WTF.

They charged it over night and it was good to go but this will be something I would check in the future when buying a $190 battery.

[normalguy]

Originally Posted by sp1tfire

I would place my bet on Intelligent battery sensor.
Check the alternator voltage with everything running, google it, output has to be 14.XX volts, don't recall exact number.
Stop by AutoZone - let them check the battery
Then maybe there is way to check IBS, no idea.
Whichever is the origin of your problem, voltage definitely can cause rough idle.
I don't see how carbon deposits or vanos could cause this, entirely different systems.

Way to be right about this. I appreciate your response and it was correct. Thanks.