Acceleration stumble at highway speed Help!

[ELCID86]

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.

Yes. Left unplugged for a few days then back in. For some odd reason it did. I still have a bit of a stumble every once in a while but not very often.

[daytona90t]

Quick update! I finally got a DME code today that I was able to see with BMW Scanner 1.4. The code is 2960[10592] O2-Sensor Before Kat Bank1. Apparently this is a code that many get before updating to the latest DME software. Since I have the latest DME software for my car and this code came up after I had the software flash done last month, I am going to go ahead and replace both pre-cat O2 sensors.

For the past few weeks my theory has been that if so many have remedied the 2,800 rpm stumble by having their DME software update to the latest version, and if the latest software revision recalibrates the DME to read the O2 sensors in a wider range; since the update didn't work for me, at least one of my O2 sensors must be failing and out of range. Now that I have a code suggesting just this, and my car now has 107,000 miles on it, I think that it is worth replacing the O2 sensors

I am currently using the (Mike's Easy BMW Tools) thread in the coding section to put together a diagnostic machine running INPA. With this I would be able to definitively check the O2 sensors and see if they are reporting out of range. Based on how this has been going, I can easily get 2 new O2 sensors in the car before I get the cable in from Amazon and figure out the BMW Tools software install.

I will report back once the new O2 sensors are in, probably next weekend.

[anandoc]

Thanks for the update. I installed 2 new Bosch pre-cat O2 sensors back in 2015 because I used to get the codes too (along with a check engine light). The codes went away for a while but I still get them sometimes...especially when I am in cruising speeds.

[daytona90t]

Upon digging further and further into the depths of internet auto forums it seems that this issue plagues not only the M54 but also the S54 engine. I just read through this entire M3Forum.net post (The M3 got hickups) and there is some good conversations in there, but just like all of the other forum discussions, no definitive solutions.

[ELCID86]

^i didn't realize that. :-(

[daytona90t]

It seems that I have finally had success at solving this issue. I replaced both pre-cat O2 sensors this morning with the Bosch 17215, re-set DME adaptations, and took the car for a drive. The car seems to be completely cured of the 2,800 rpm stumble/hesitation issue and feels more responsive and eager to pull all the way through the rev range than I have ever experienced. After 6 months of researching, replacing a bunch of parts, and verifying that I already had the most up to date DME software revision, it seems to have been a degraded pre-cat O2 sensor all along. I never had a check engine light, or even a code until last weekend.

Hopefully my experience can help someone else on here from going completely insane trying to cure this issue. If you have had your DME updated, or verified that you already have the most up to date software revision, and even if you don't have a code indicating a bad O2 sensor, replace your pre-cat O2 sensors.

[anandoc]

Thanks for continuously updating this thread.

So I guess in my case, I need the updated DME software to solve this since I replaced my pre-cat O2 sensors with the Bosch ones in 2015. I also have a GAS modified DISA valve.

[holyc0w]

It seems that I have finally had success at solving this issue. I replaced both pre-cat O2 sensors this morning with the Bosch 17215, re-set DME adaptations, and took the car for a drive. The car seems to be completely cured of the 2,800 rpm stumble/hesitation issue and feels more responsive and eager to pull all the way through the rev range than I have ever experienced. After 6 months of researching, replacing a bunch of parts, and verifying that I already had the most up to date DME software revision, it seems to have been a degraded pre-cat O2 sensor all along. I never had a check engine light, or even a code until last weekend.

Hopefully my experience can help someone else on here from going completely insane trying to cure this issue. If you have had your DME updated, or verified that you already have the most up to date software revision, and even if you don't have a code indicating a bad O2 sensor, replace your pre-cat O2 sensors.

That sounds more like the DME adaptation reset.

[daytona90t]

That sounds more like the DME adaptation reset.

No, it wasn't just the DME adaptation reset. I have been chasing this issue for 6 months and have reset DME adaptations a number of times myself, plus the DME re-flash that I had done at the dealer 6 weeks ago wiped the entire DME and reloaded the latest software revision. None of the previous adaptation resets or the DME re-flash had any effect.

[BMWCurves]

Cool, thanks for following up!

If you can, you might consider cataloguing all your attempts at fixing the issue plus the final solution in your original/first post so other people can find your solution quickly!