[1stAndLastBMW]

Originally Posted by Wires

Thanks troll!

How am I trolling? I added content on how I was able to reproduce the mentioned issue while also helping to validate that the others experiencing the issue arent going mad.

Just because I'm completely frustrated and jokingly said I was going electric, doesn't make me a troll. Now if I had replied with "BMW sucks and I'm going electric" and that was the only thing in the reply, then yes, you could have called me out.

[BuffaloSoldierH]

Same here and particularly when the car is cold

[TK335iMSPT]

I have a 14 335i and these exact symptoms have have started at the 30k mile range. I absolutely hate and have been to bmw about 10 or so times now complaining. Each time it's the same answer. "We can replicate what you are describing but there are no faults with the car and it is operating as designed".
Very frustrating to experience on a 60k+ car. It's especially embarrassing when you are in traffic with family or clients in the car.

14 335i Xdrive 8at 55k miles

[RoIIouT]

Originally Posted by TK335iMSPT

I have a 14 335i and these exact symptoms have have started at the 30k mile range. I absolutely hate and have been to bmw about 10 or so times now complaining. Each time it's the same answer. "We can replicate what you are describing but there are no faults with the car and it is operating as designed".
Very frustrating to experience on a 60k+ car. It's especially embarrassing when you are in traffic with family or clients in the car.

14 335i Xdrive 8at 55k miles

Just hammer it every time you take off and no one will notice.

[Wires]

Originally Posted by 1stAndLastBMW

How am I trolling? I added content on how I was able to reproduce the mentioned issue while also helping to validate that the others experiencing the issue arent going mad.

Just because I'm completely frustrated and jokingly said I was going electric, doesn't make me a troll. Now if I had replied with "BMW sucks and I'm going electric" and that was the only thing in the reply, then yes, you could have called me out.

And your screen name...

[Briland33]

I noticed this in the exact same conditions. My car was juttering like i was rapidly applying gas and releasing.

[not1337]

Anyone find a resolution for this issue? I’m finding it absolutely annoying

[kern417]

You're lugging the engine. Don't do it. Downshift.

[1stAndLastBMW]

Originally Posted by Wires

And your screen name...

Yep, still not trolling. Come back in 50 years, my username will checkout. I can 100% guarantee you that I will not own another BMW for the rest of my life - especially after BMW of America sits here and tells me that they can replicated the issue but that its operating as expected.

[1stAndLastBMW]

Originally Posted by kern417

You're lugging the engine. Don't do it. Downshift.

Wish it were that simple. I can replicate up to ~2000 rpm. Hardly my definition of "lugging".

I guess there's a silver lining to COVID? - I've only driven the car twice since March of 2020.

[Robs335iproblems]

So I have a 2018 340xi with the same issues and under the same conditions as noted in post #18. I've had MHD stage 1 and stage 2 and then removed it. I've had XHP stage 2 and then removed it. In all cases I've had the same issues. Additionally, it gets worse when in ECO mode under the same drive conditions in post #18. In other forums, it speaks to a throttle issue where the throttle opens, the DME thinks that it's too aggressive, closes it and then it repeats over and over, very quickly, hence the bucking. This can be seen with the sport displays for hp and torque as you'll see the torque jump up/down to correspond with the bucking sensation. This has been confirmed by logging with MHD. There have been suggestions of resetting adaptations for lambda, air, fuel and throttle. Some have noted this has fixed the issues however, I'm not certain that I've see the success yet. It's very, very odd as my 2015 435 with the N55 doesn't have this issue, so it must be related to the B58 engine.

[Robs335iproblems]

Update. I had the car completely reprogramed by the dealer. Actually, they needed BMWUSA to log into their system to get it to reprogram properly. Same issue when I drove home from the dealer. The only other two mods I have are a BMS intake and a AR High flow catted downpipe. I'll be removing both to see if either one caused the issue. Perhaps there's an exhaust leak somewhere around the downpipe. I can't see any other issues with intake or vacuum leaks. The dealer was able to replicate the issue however, since I had the intake and downpipe, BMW blamed the issues on the mods. So once I remove them and it still has an issue, they would be willing to open a case and see what they can find out. I'll post any findings in order to help anyone else who's still experiencing this issue and can't find a solution.

[Wires]

Originally Posted by Robs335iproblems

Update. I had the car completely reprogramed by the dealer. Actually, they needed BMWUSA to log into their system to get it to reprogram properly. Same issue when I drove home from the dealer. The only other two mods I have are a BMS intake and a AR High flow catted downpipe. I'll be removing both to see if either one caused the issue. Perhaps there's an exhaust leak somewhere around the downpipe. I can't see any other issues with intake or vacuum leaks. The dealer was able to replicate the issue however, since I had the intake and downpipe, BMW blamed the issues on the mods. So once I remove them and it still has an issue, they would be willing to open a case and see what they can find out. I'll post any findings in order to help anyone else who's still experiencing this issue and can't find a solution.

I'd suspect the intake messing with flows to the MAF sensor. These cars run very lean all the time, so that could be the issue. Cannot comment on the BMW specifically, but others have mentioned issues and CEL's with aftermarket intakes.

Unless you had an exhaust leak at the v-band area to the DP, you shouldn't be having issues there (unless that O2 sensor is damaged, but then you should get some sort of a CEL code).

[Robs335iproblems]

You're exactly correct. I had a BMS intake in the car (and the high flow catted downpipe) and I was going to try two different experiments. The first was simply removing the intake and putting the stock one back on. After putting the stock intake and driving around for a while, the surging seemed to be gone. I thought that I might have felt it once or twice, but since I'm looking for it, it might have been felt between the ears. So I would agree that somehow, under very light throttle, the volume of air was messing with the MAF and it was struggling to keep the system running correctly. I think the MAF couldn't adjust the system quickly enough and while struggling to do so, it caused what felt like an oscillating throttle (or surging). The second experiment that I was going to try (but didn't have to) was simply pulling the MAF connector off and let the car run open loop. My thought was if the DME programming was correct, then running open loop would prove that it was sensor related (closed loop caused the problem), which I felt would point me back to the MAF (and/or an intake related issue).

So for those folks suffering from surging problems, assuming it's not vacuum related, look at the intake. Make sure it's tight and all clamps are on correctly. A dirty MAF might be to blame as it's possibly having issues reporting flow properly to the DME. I'd also suggest trying to simply disconnect the MAF sensor and run open loop to see if that solves the issue. If it isn't surging when running open loop, it's more than likely sensor related. If there are no codes when driving normally, it's probably not O2, so I'd look for intake related issues.

I'll report back if it returns, but I agree that it can't be exhaust, but the intake and exhaust were the only two components that have been replaced in the car, so that's what I was focusing on.

Also, I did have XHP stage 1 and 2 and MHD stage 1 and 2 in the car at one point or another and since they had been removed and the surging was exactly the same after a full reprogram, I think that confirms that neither tune were the issue. Hopefully that helps some other folks when it comes to deciding whether or not to get a tune.

[claytonap1]

I have a BMS intake as well. I get the bucking in every driving mod (comfort/ sport/ sport+). Haven't taken the car to the dealer as my car is pretty modified. Always happens in rpm range 1500-2200, in any gear (even cruising on the freeway in 7th gear). I'll swap the stock intake back in to see if that helps the issue. I've just learned to deal w/it for the past 6 months. I tried resetting adaptations, removing the trans tune (thought it was that) but bucking remains. Its gotten to the point to where i'm hesitant now to floor the car cuz it'll buck hard before moving.

[Robs335iproblems]

I have the same issue as it does happen in all gears/driving modes, but it's more prevalent in ECO and Comfort. Due to the touchy throttle in sport/sport+ I don't find myself driving at a light, constant speed. But in the other modes, even doing 70 on the highway, I can feel the surging/oscillation. My other car is a 435 with the N55 and similar mods, but that one has a Dinan intake (and MHD stage 2, downpipe, larger intercooler, etc.) with no surging issues. I think the B58 with the water cooled intercooler and different routing for the intake/charge pipe, etc. is much more sensitive with air volumes, so under light throttle, the closed loop sensors are trying to adjust and then it gets into a weird oscillation. I'll be curious to hear what happens when you swap the intake. I've also read that the B58 intake really isn't restrictive. I don't think you're going to starve the stock turbo, even with a tune, with the standard intake. After a few weeks of driving, if I don't see any issues, I'll retune the car and see if anything changes.

[Robs335iproblems]

Update. Two days after removing the BMS intake and going back to stock, surging is still there. I'm tired of searching and reading hundreds of other posts with no solution outside of odd VANOS replacements (N54, N55) and LPFP lines that were loose. There is absolutely no reason that this should be happening. How is it that a car can't accelerate correctly? It only has 28k miles on the clock. This is the most frustrating experience that I've ever had with a BMW.

[claytonap1]

have you tried cleaning or replacing the MAF sensor?

[normanvreede]

First post, but I've been self-maintaining/repairing BMW's since 2008 (my 2003 e46 M3 still running beautifully thanks to these blog sites) Don't know if this will help, but I have a F36 440i xDrive 2018, and I introduced this very problem (low rpm/high gear/high speed surging) by adding a vargus oil crankcase breather to the vehicle. It wasn't the breather itself (the ceramic ball in the breather prevents air infiltration into the oil crankcase during vacuum conditions), but the fact that the breather wouldn't remain seated to the valve cover for very long (it would literally rotate loose to almost falling off, allowing air to leak in to the crankcase under vacuum), and then these symptoms would occur. Every time I removed this device and put the stock oil filler cap back on, the problem was gone. If I bent the tabs of the vargus crankcase breather in an attempt to prevent the loosening of the breather, it still rotated loose, and the problem reoccurred that again resolved by putting the stock oil cap back on. Not everyone has a Vargus oil breather, but what I'm wondering is if there is a vacuum leak (under low rpm/low boost situations) in the oil crankcase ventilation system or the air intake system after the MAF sensor that is allowing unmetered air to be drawn in to the turbo/engine under vacuum (not boost) conditions. The engine then runs lean d/t unmetered excess air, the computer compensates, and then it surges, etc... Just a thought.

[Robs335iproblems]

Yes, I cleaned the MAF when I put the stick air box and filter back on.

@normanvreese. Thanks for posting. Like you, I’ve been working on BMW’s for about the same time. It’s a hobby. This is driving me nuts. I much rather be working problems on an e46 or e60. Vacuum leaks seem the be the most reasonable cause. I will say that it happens after the car warms up, which might point to something expanding and then a gasket or o-ring or otherwise let’s in a small amount to air somewhere. I’ll try and look at the oil crankcase vent connections to see what I can see. Not sure how easily it will be to test or check for cracks, etc. I don’t think it’s intake related, but I can check.

[normanvreede]

Lots of cheap/thin plastic in these areas where unmetered vacuum air leaks could present problems. Mine occurred only because I introduced the problem with a aftermarket part. It's just a thought, but if my vehicle started having this surging issue in the future, the first item I'd go after is the PCV rubber diaphragm that's already proven to be failure prone in the the B58. Replacement parts are now cheap to obtain and install (Ross Engineering and others), and I'm guessing that in some of these cases smaller leaks/holes in the rubber diaphragm may present as a surging issue instead of the whistling sound/white smoke issue at idle we have seen reported with larger diaphragm leaks. Again, just a thought.

[Robs335iproblems]

I disconnected the MAF and there was no change in the surging. I cleaned the MAP in the charge pipe and the T-MAP in the intake and there was no change. Checked for leaks with starter fluid and nothing. The car is buttery smooth when idling, so I'm thinking that vacuum is not the issue. When the car is cold (in the morning as opposed to after it's been driven and restarted), it runs fine (no surging). So it made me think it has to be related to something warming up, or waiting until the car get's into closed loop. So I started really thinking about the whole combustion process and began searching forums outside of BMW. There are literally hundreds of surging posts. Based on all of that thinking and reading, I'm going to disconnect the upstream 02 sensor, force the car into open loop and see if that works. Since the unplugged MAF (and air intake) didn't have any change, the 02 sensor is next in my thinking. After that, the only things left would be fuel and spark, which I don't think it's either one. Rail pressure if fine and there are no codes for misfires, so I don't think it's spark/coil related. While not BMW's, there are countless other posts regarding surging, bucking, etc. and many have ended up with upstream 02 sensor problems, even when there wasn't a CEL or otherwise. So that's next on my list. The thinking is that under light acceleration, the 02 sensor is reading, but the readings are slow, therefore it's basically trying to make late adjustments to air/fuel and then when they change, it's late to make the next adjustment, and does overshoots one way and then the other, which is why it begins what feels like an oscillating throttle. When reading properly the sensors usually adjust in milliseconds, so you'd never actually feel when it's doing what it's supposed to do. Somehow, the normal lambda oscillating readings are being driven back into the DME improperly and the car is trying to adjust air/fuel. The 02 sensors are the only sensor readings that actually oscillate as part of their normal operation as opposed to sensors that take readings (temp, pressure, air flow). If they are slow to respond, then it might be causing the issue while at the same time, not necessarily generating a code.