Acceleration stumble at highway speed Help!

[Tunes]

I had this issue with mine and it was the coil. Changed them all and its all good.

[ELCID86]

^ hadn't thought of that. 6 new coils may be in order

[daytona90t]

I just canceled the appointment for the dealer since the DME re-flash seems to be pointless. I am going to re-set my adaptations and see if that has any effect. I need to put together a better diagnostic system than just the carsoft scanner or the P.A. Soft BMW scanner 1.4. I really want to be able to check everything such as DISA and VANOS function, spark advance, and O2 values in real time.

Without any codes other than the 2772 Tank Vent Valve I don’t have much to go on. As suggested by ELCID86, I am going to check my fuel vapor components in the rear wheel well. If I can’t detect any physical issues or a vacuum leak, I will replace the vent valve. I am already planning on replacing the entire CCV system and the coil packs this summer as part of my 100,000 mile preventive maintenance. I will keep you all posted of any updates, developments or solutions.

[daytona90t]

I finally got some time to work on the car this weekend and got a ton of stuff done, unfortunately none of it remedied the 2,800 rpm hesitation issue. I replaced me entire CCV system with the OEM cold climate version, not as bad of a job everyone makes it out to be. While in there I also inspected and cleaned the throttle body, idle control valve, and DISA, rebuilt a few years back with the G.A.S. kit and still looks good. I also replaced all 6 coil packs with new Bosch ones and replaced the fuel tank vent valve. To finish off I checked fuel pressure at the rail, a nice 55 psi at idle, and reset DME adaptations.

I am not too upset as all of the above was either part of my planned 100,00 mile preventive maintenance for this summer, or it was to address the check engine light and 2772 code that I was getting. The other labor, inspection, and cleaning, was also piece of mind. The only things left on my list of possibilities are a failed VANOS solenoid, O2 sensors, or software issue. Without any codes I cant be sure.

With that said, I guess that I am back to square one with the hesitation issue. I need to put it out of my mind for a few weeks, as I am now going to be busy through the rest of June with work, fathers day, and my daughter's first birthday party. I will need a state inspection in July and while at the dealer I may see what, if anything I can have them do for a diagnosis, and perhaps have them see if it is possible that there is still a software related issue, even though I should have the latest software revisions.

[anandoc]

Have you rebuilt the VANOS seals? Slater helped do my VANOS seals a few weeks ago and I am pretty sure that the 2800 hesitation got better after that. Mind you, I still have a hesitation but its not as terrible as it used to be before the VANOS rebuild.

[slater]

Have you rebuilt the VANOS seals? Slater helped do my VANOS seals a few weeks ago and I am pretty sure that the 2800 hesitation got better after that. Mind you, I still have a hesitation but its not as terrible as it used to be before the VANOS rebuild.

i don't think it's related to VANOS as i didn't develop the 2500-3000rpm stumble until well after rebuilding the VANOS in my car. it's gotta be something else... something perhaps not obvious.

i know shawn said unplugged the DISA cured it for him (i think i remember that correctly?), and the later/latest BMW DME code fixes it, but also doesn't it disable the operation of the DISA? just thinking out loud here.

[daytona90t]

Have you rebuilt the VANOS seals? Slater helped do my VANOS seals a few weeks ago and I am pretty sure that the 2800 hesitation got better after that. Mind you, I still have a hesitation but its not as terrible as it used to be before the VANOS rebuild.

Hi,

Yes I actually rebuilt the VANOS last fall with the Beisan Systems seal and rattle repair kit. After the VANOS rebuild I definitely felt more power and better throttle response. The 2,800 rpm hesitation that I am experiencing didn't begin until about 3 months ago, about 6 months after I rebuilt the VANOS. I am thinking about possible VANOS solenoid issue though. In hind sight I think I would have been better of going with the Dr. VANOS rebuild. It's not that rebuilding the VANOS was difficult, but I am fairly sure that Dr. VANOS also cleans, inspects, tests, and warranties the whole unit, including the solenoids.

[daytona90t]

i don't think it's related to VANOS as i didn't develop the 2500-3000rpm stumble until well after rebuilding the VANOS in my car. it's gotta be something else... something perhaps not obvious.

i know shawn said unplugged the DISA cured it for him (i think i remember that correctly?), and the later/latest BMW DME code fixes it, but also doesn't it disable the operation of the DISA? just thinking out loud here.

It seems to be the consensus that my car has the latest software versions. My DME was updated in 2006 to 7561520 and my EGS was updated in 2008 to 7546860. I can verify with my scan tool that at 4,000 rpms on the nose, my intake changes from long pipe to short pipe, or DISA going from closed to open.

[daytona90t]

This past week I had the car at my local dealer for an alignment and state inspection. Since it was already there I asked them to check my DME calibration version and to verify that it was in fact the latest and final version for my car. DME calibration 7.561.520, 7.561.521 is the latest and final version for my car. Incidentally, even though I asked them only to check and verify the version and update if a newer calibration version was available, they went ahead and reloaded the same version anyway. This had absolutely no affect on the 2,800 rpm hesitation issue!

Since I asked for an update and not for the same version to be reloaded, I wasn't very happy when they tried to charge me for it. Based on the perceived miscommunication we worked something out so that I am not completely out of pocket for a service, but that is another story.

If you already have the latest calibration, a possible software update to fix this issue can be crossed off the list. It will have no affect. If you can verify that you have an older software calibration, there may be some hope. As for me, I am back to the drawing board.

[anandoc]

Thanks for the update.

And the search continues...