[Mirgus]

If its still under warranty i would let BMW take for it the issue. Without a recorded log its really hard to tell what the engine is doing. I can recommend MHD for logging.

[Lord90]

unfortunately I don't have a warranty and although I showed the reason to many technicians, they couldn't determine it. I have a mhd universal device and I didn't buy the mhd software. Can I record without buying it? Also, I think the flywheel in the vehicle has changed, could it be related to that? If I can record without purchasing in the application, can you explain?

[armenh7]

Originally Posted by isenc2

Okay, so I have a bit of a different situations than most of yall. I do not currently experience bucking or stuttering, just a bit of rough idle on cold start and very rarely the car would hesitate just a little and during hard upshifts. Now, I have changed both of my solenoids just for preventative maintenance. The cold start idle is a lot smoother and the car shifts a lot smoother as well. I have changed all my fluids about 10k ago, engine oil changed every 5000miles and I run 0w30 LL-01FE bmw oem oil. This is definitely worth doing at around 70k miles. I bought them on FCP euro, and the swapped out old solenoids are interesting. Since in my case nothing is failing, both of them looked okay, however, one of them is just a little stuck, and slow to actuate, which makes sense.

Would you have a log to share? I think mine is the same exact situation. They're just starting to go. My idle feels rougher than when I bought the car a year ago. I changed motor mounts and it still felt the same.

[Mirgus]

Originally Posted by Mirgus

Hello everyone

i've bought an F22 M240i 2017 with ~35k miles and i have the bucking issue since i picked up the car :/. Currently i am still under warranty but it seems hard to figure out the issue.

I have following issues:

• car starts bucking at ~1000-1100 rpm on a slight uphill and only when the engine is warm ( when the engine is cold the VANOS arent working)
• hesistation feeling on accleration from standstill (slight delay)
• engine sometime "stalls" accelerating from standstill in traffic when the engine is still in coldstart

So i brought the car to the dealer for diagnosis and following fault code existed:

• 21A02D: combustion control idle irregular

They have updated the car to a newer i-level and calibrated the VANOS. After the i-level update and VANOS recalibration the IDLE was rougher but the throttle response was much better and the bucking was gone.

I didnt have any issues for 6k miles but the bucking returned . Interestingly the IDLE improved when the bucking returned. So i bought a MHD monitor license and hoped for an easy fix... but unfortunetly the VANOS target angles are oscillating and the VANOS are doing what they suppose to do according to the DME
https://datazap.me/u/mirgus/log-1722...og=0&data=5-28

So i returned to the dealer and apprently last time they didnt update the i-level to the latest one... so they did update the i-level again. This time to i-level 24-07-520 and they recalibrated the VANOS again. Now the IDLE is rougher but at least for know the issue is gone again... but i am pretty sure it will return.
Heres a log after the i-level update.

When the car is idling in neutral the VANOS (exhaust and intake) do some funky stuff periodically... not sure whats going on her
https://datazap.me/u/mirgus/log-1724772069


Currently i dont have any solution yet :/ in case i find one i will let you know.
Greetings from germany

So a small update from my side. The car was in the workshop and they tested the intake for leaks with a smoker... and they found an air leak directly behind the mass flow sensor. That stupid resonator was cracked and its apprently a common issue. Even found a picture online from someone who had also a crack in the resonator

https://www.1erforum.de/attachments/...3-jpeg.119285/

Now i have reseted the valvetronic adaptions again. I will give you guys an update in case the issue isnt fixed for good.

[gasoline]

Originally Posted by Mirgus

So a small update from my side. The car was in the workshop and they tested the intake for leaks with a smoker... and they found an air leak directly behind the mass flow sensor. That stupid resonator was cracked and its apprently a common issue. Even found a picture online from someone who had also a crack in the resonator

https://www.1erforum.de/attachments/...3-jpeg.119285/

Now i have reseted the valvetronic adaptions again. I will give you guys an update in case the issue isnt fixed for good.

Hi Mirgus,
I had vanos actuators replaced and bucking was gone. Still it is fine.
But as you experienced; the idle or in general the engine is not smooth as before.
In addition; I feel shudder during stop at traffic lights in D, when the engine is warmed up. It does not shudder when the engine is cold. Did you have a symptom like this when there was no bucking but idle was harder?

[Mirgus]

Originally Posted by gasoline

Hi Mirgus,
I had vanos actuators replaced and bucking was gone. Still it is fine.
But as you experienced; the idle or in general the engine is not smooth as before.
In addition; I feel shudder during stop at traffic lights in D, when the engine is warmed up. It does not shudder when the engine is cold. Did you have a symptom like this when there was no bucking but idle was harder?

Hey ,

yes what you are describing is what also happened to me when the adaptions values from VALVETRONIC have been reseted. When the bucking came back the engine ran smooth again while idling.

Unfortunetly the broken inlet pipe was not the fix for my bucking issue today it came back... and now the engine is idling smooth again

I dont know whats causing the issue Somehow the engine is adapting parameters that result in a smoother idle but therefor cause the bucking

[gasoline]

Originally Posted by Mirgus

Hey ,

yes what you are describing is what also happened to me when the adaptions values from VALVETRONIC have been reseted. When the bucking came back the engine ran smooth again while idling.

Unfortunetly the broken inlet pipe was not the fix for my bucking issue today it came back... and now the engine is idling smooth again

I dont know whats causing the issue Somehow the engine is adapting parameters that result in a smoother idle but therefor cause the bucking

Hi,
I talked to a mechanic and he also focused on “valve” inside vanos. That is also one potential problem point and pointed that the replacement of actuator may not be enough.
Did you have these valves checked?

[nahtanoj1]

Hi. Lots of good details in the posts above - Thanks.

I'm in a 2018 340xi stock with a MHD stage 1 93oct tune that I recently installed. Before the tune I have felt no issues with the car surging though the car does sees to have "turbo lag". I am finding when accelerating hard (not normal driving around town like some have reported in this thread) that I have uneven power. I took a video of the gauges and at around 250HP & between 360 and 480 torque 5th gear that my power is not smooth you can feel the car surging. I have 50k miles and original spark plugs and have not ever cleaned the injectors on this car. Shall I take it to my mechanic and get injector cleaning and new plugs AND replace both Vanos actuators? Or should I just start with the plugs and injector cleaning? Also what spark plugs would you use in my situation - are the OME ok? I'm not planning to go above the stage 1 tune. Thanks for responding!