[sinnertie]

Hi all,

I am new here with my first post. I am getting grey hair at this point and am really desperate for any help with my 2007 BMW E90 335d.

I have had this car for about a year now. Recently, when pulling out from the parking lot, I noticed strange RPM behavior where the RPM would fluctuate up and down during steady driving. As the days passed, the car's condition worsened. The fluctuation became more noticeable, accompanied by juddering, especially between 50-65 mph and uphill. Pushing the accelerator harder would make it go away. After doing some research and talking to a friend, I was advised to perform a transmission service since I couldn't tell whether it had ever been done on the car, and considering it is almost at 190k miles, it's about time.

I went to a garage that specializes in transmissions, asked them for a diagnostic and service, and paid £350, only to have exactly the same issue as before. According to their technician, it's the engine (without driving the car) because there are error codes stored, which I was aware of as they have been there since I bought the car. I will attach the list of them below just in case.

I went to another mechanic and asked them to look at the car. After test driving it, they said it could be the torque converter as well as the gearbox. Considering all that I read and what people were advising, I decided to replace the torque converter and the seal sitting between it and gearbox.

A refurbished TC was installed, which I sourced myself from a reputable place, along with a new pan and transmission fluid yet again because there were a lot of metal shavings in the fluid (shown in the video attached). After spending £1600, the issue was gone, but the gearbox started doing some weird gear changes. For example, as I was rolling to a stop at a roundabout, if I decided to pull out instead of stopping, even a normal press on the acceleration pedal would sometimes cause the car to kick as if someone bumped into me from the back. Apart from that and a bit of rough gear changes every now and then, it was fine. That lasted for two days before the RPM started fluctuating again at a steady speed, as shown in the video attached below. Today, as I took the car for a drive, it also started juddering at certain speeds again, although not as bad yet, so it seems like it is happening all over again. Any idea what it could be, what to look into, or what my next steps should be would be greatly appreciated. Thinking that I just spent £1600 on a TC that might be damaged again makes me freak out. If I missed anything important please let me know.


Gearbox adaptations has been reset. I attached INPA error code printout. I am absolutely certain that the DME/DDE errors have been there since I bought the car. I should mention that the car has no DPF, swirl flaps, nor EGR. All of that was done by previous owners. It has been remapped as well, but I cannot say if anything was done to the gearbox, which by the way is 6HP28.


Video of the RPM fluctuating 2 days after torque converter replacement:

Video from mechanic of the TC change and the metal shavings:
https://youtube.com/shorts/a9GVb1y1y9Y

[ppointer]

I had these symptoms on my 2009 528i two years back, with the ZF transmission. It was the torque converter that was failing. Unfortunately, according to my trusted indy mechanic, the transmission had to be rebuilt. Was not cheap, but I did not want to replace the car. No problems since getting the car back.

[sinnertie]

Originally Posted by ppointer

I had these symptoms on my 2009 528i two years back, with the ZF transmission. It was the torque converter that was failing. Unfortunately, according to my trusted indy mechanic, the transmission had to be rebuilt. Was not cheap, but I did not want to replace the car. No problems since getting the car back.

Thank you for your response. Do you think that the new torque converter that I had put into the car will be gone at this point as well?

[krashDH]

Originally Posted by sinnertie

Thank you for your response. Do you think that the new torque converter that I had put into the car will be gone at this point as well?

What shape is your valve body and solenoids in? This is the brain of your transmission and controls everything.

I just finished up splitting my VB, installing a Sonnax Zip kit, new VB solenoids, VB seals, fluid and pan and the transmission feels worlds better than it did before.

My issues weren't severe but there was some sporadic shift feeling, almost like I was getting bumped from behind during shifts. Some shifts were ok, while others weren't.

Sounds like neither of the shops you went to have a clue what to look for or how to diagnose, and jump straight to throwing very expensive parts at the problem.

[sinnertie]

Originally Posted by krashDH

What shape is your valve body and solenoids in? This is the brain of your transmission and controls everything.

I just finished up splitting my VB, installing a Sonnax Zip kit, new VB solenoids, VB seals, fluid and pan and the transmission feels worlds better than it did before.

My issues weren't severe but there was some sporadic shift feeling, almost like I was getting bumped from behind during shifts. Some shifts were ok, while others weren't.

Sounds like neither of the shops you went to have a clue what to look for or how to diagnose, and jump straight to throwing very expensive parts at the problem.

I really can’t tell, I strongly believe nothing has been done on that gearbox since it was put there when car was manufactured.
I totally agree with what you said about those garages.

I am booked to come back on 3rd of June but over the phone the guy already prepares me for gearbox replacement.. I guess I can sort of swallow it if I can be sure this will fix the problem and if the torque converter that just went in has not been damaged.

I got a feeling that they are the type where they would rather just throw a used gearbox at the car instead of trying to open it up and trying to fix it.

[ppointer]

Originally Posted by sinnertie

I really can’t tell, I strongly believe nothing has been done on that gearbox since it was put there when car was manufactured.
I totally agree with what you said about those garages.

I am booked to come back on 3rd of June but over the phone the guy already prepares me for gearbox replacement.. I guess I can sort of swallow it if I can be sure this will fix the problem and if the torque converter that just went in has not been damaged.

I got a feeling that they are the type where they would rather just throw a used gearbox at the car instead of trying to open it up and trying to fix it.

I don't know enough about this transmission. I did ask my mechanic if just the torque converter could be replaced, and he said no, the rebuild of the transmission was the required repair.

[sinnertie]

Originally Posted by ppointer

I don't know enough about this transmission. I did ask my mechanic if just the torque converter could be replaced, and he said no, the rebuild of the transmission was the required repair.

Appreciate you doing that, thank you.

[krashDH]

These auto transmissions are pretty robust. I would not think, that even if still original, it would need to replaced unless it was completely beat on and neglected during it's life.

Rebuilding the valve body with the Zip kit, new solenoids and seals, is around $500 USD for parts and a days worth of work if you do it yourself. I would sure rather sink that into a perfectly good transmission rather than have a shop tell me it just needs to be replaced.

Like I said, auto transmissions are usually the achilles heel of a vehicle, but this ZF transmission is a stout sucker.

[MidWillamette335d]

Just my 2 cents...Don't spend any more time or money on the tranny before clearing some DDE codes. As mentioned before, they are pretty stout units, and unless it was hammered on previously it's probably okay. If anything, download XHP, you don't need to buy the license or map packs, but you can use it to check your clutch pressures and times. It might give you an idea of the health of your tranny in general.
It looks like your glow plug controller is shot, probably due to a bad thermostat (probably not your issue). Coincidentally tho, there are the same number of instances of these codes stored (glow plugs) as code 4687 which I believe is related to the throttle valve actuator or ASV as some may call it (if you google it, which I'm assuming you've done at this point, there are reports of fluctuating throttle with this code). Code 483D is also related to your throttle. Perhaps the issue that threw the original code has just gotten worse enough to begin to affect performance they way you're experiencing? Again, just my input, hope you get it sorted one way or another....

[sinnertie]

Originally Posted by krashDH

These auto transmissions are pretty robust. I would not think, that even if still original, it would need to replaced unless it was completely beat on and neglected during it's life.

Rebuilding the valve body with the Zip kit, new solenoids and seals, is around $500 USD for parts and a days worth of work if you do it yourself. I would sure rather sink that into a perfectly good transmission rather than have a shop tell me it just needs to be replaced.

Like I said, auto transmissions are usually the achilles heel of a vehicle, but this ZF transmission is a stout sucker.

Thanks and that's exactly what I kept hearing about ZF gearboxes which really surprised me once this started happening as I would expect gearbox to go in this car last.

I will go that route. I really don't feel like changing the gearbox and hoping for the best especially that I personally would struggle to source one that I could be sure is in decent condition.

Originally Posted by MidWillamette335d

Just my 2 cents...Don't spend any more time or money on the tranny before clearing some DDE codes. As mentioned before, they are pretty stout units, and unless it was hammered on previously it's probably okay. If anything, download XHP, you don't need to buy the license or map packs, but you can use it to check your clutch pressures and times. It might give you an idea of the health of your tranny in general.
It looks like your glow plug controller is shot, probably due to a bad thermostat (probably not your issue). Coincidentally tho, there are the same number of instances of these codes stored (glow plugs) as code 4687 which I believe is related to the throttle valve actuator or ASV as some may call it (if you google it, which I'm assuming you've done at this point, there are reports of fluctuating throttle with this code). Code 483D is also related to your throttle. Perhaps the issue that threw the original code has just gotten worse enough to begin to affect performance they way you're experiencing? Again, just my input, hope you get it sorted one way or another....

Thank you and I do plan on doing glow plugs, controller and now after reading what you said throttle valve actuator which has not been done at least by myself and see what difference it will make. If the car gets up to temperature alright would you say I should do thermostat anyway?

The reason I stick to blaming gearbox so much is due to that specific juddering at all sort of speeds, mostly steady and especially uphill. It feels like driving over the gravel which makes me point at gearbox.
I will test it using XHP as advised, just need to do proper research prior as I never used that software nor know the value ranges etc.

[MidWillamette335d]

I think if you get to temp your thermostat probably is fine, and likely your controller is out. The thermo is pretty easy and cheap to replace however. I guess why I originally chimed in is cause I had a similar issue with my 4Runner, totally different beast I know. I had a clunk and what felt was a bump from behind, vehicle started to shudder when giving any substantial amount of throttle. Thought my tranny was toast due to these rigs suffering from the "strawberry milkshake" effect when tranny fluid and coolant combine after the wall in the radiator corrodes. I was over-fueling in cyl 4, turned out to be a bad spark plug wire. Not saying it's not your tranny, but good to rule out any known issues...

[sinnertie]

Originally Posted by MidWillamette335d

I think if you get to temp your thermostat probably is fine, and likely your controller is out. The thermo is pretty easy and cheap to replace however. I guess why I originally chimed in is cause I had a similar issue with my 4Runner, totally different beast I know. I had a clunk and what felt was a bump from behind, vehicle started to shudder when giving any substantial amount of throttle. Thought my tranny was toast due to these rigs suffering from the "strawberry milkshake" effect when tranny fluid and coolant combine after the wall in the radiator corrodes. I was over-fueling in cyl 4, turned out to be a bad spark plug wire. Not saying it's not your tranny, but good to rule out any known issues...

Oh wow, I see. Just looked around and realised how simple of a job it is and part is cheap as well so I will do it all together.

One more question if you don't mind. One of the codes "447B" is described as "Oxygen sensor, bank 1". Would you advise replacing the sensor as well while I am working on the vehicle or should I do more testing before throwing another part at it?

[MidWillamette335d]

I mean, I would. Please understand that I'm simply suggesting what I would do in your scenario. Just dealing with your tranny issue would have generated an internal dialogue for me of "just walk away at this point and come back to it later, there's other stuff to be dealt with...lets rule those out". Personally, I'd deal with all the easy known (codes) stuff (engine), then come back to your tranny. Being that the O2 sensor does affect drivability to an extent, yes, I would replace it...if it were me. Good luck....

[sinnertie]

Originally Posted by MidWillamette335d

I mean, I would. Please understand that I'm simply suggesting what I would do in your scenario. Just dealing with your tranny issue would have generated an internal dialogue for me of "just walk away at this point and come back to it later, there's other stuff to be dealt with...lets rule those out". Personally, I'd deal with all the easy known (codes) stuff (engine), then come back to your tranny. Being that the O2 sensor does affect drivability to an extent, yes, I would replace it...if it were me. Good luck....

That's exactly what I wanted and I appreciate it is your view and approach but it helps me aid my thinking. Thank you kindly for all your help!

[barf]

The TQ (torque converter) can be rebuilt and just the TQ can be replaced.
Your initial diagnosis was 100% bad TQ converter disc/clutch. Usually it's due to wear and they usually last around 300k km.

Was your TQ a new part or was it rebuilt? For that price i hope it was brand new.
Over here we can get TQ rebuilt for around 350€. They cut the TQ open, replace the disc and then weld it back together.
The clutch like disc in TQ goes bad over time, usually impellers are good.
Are you certain the TQ you got was correct for your vehicle? It could also be a badly rebuilt TQ converter that's the issue. ZF TQ-s have a certain preload on the TQ (Yes it is always slippin) If it's too high this could be the issue but this is the problem of the manufacturer.

Of course your issue could also be caused by bad solenoid valves or valvebody.
You should also replace the rubber seals that sit between valvebody and the transmission, they do not cost much, maybe total max 50$, I can get ZF for cheaper than that.

From your symptoms after you replaced the TQ i would presume that your TQ was locked more than it needed to be.

Since without diagnostics all we can do here is speculate, i would bet bad TQ without more information. Otherwise you would have probably faults in EGS and i haven't seen valvebodys go bad like this.

[sinnertie]

Originally Posted by barf

The TQ (torque converter) can be rebuilt and just the TQ can be replaced.
Your initial diagnosis was 100% bad TQ converter disc/clutch. Usually it's due to wear and they usually last around 300k km.

Was your TQ a new part or was it rebuilt? For that price i hope it was brand new.
Over here we can get TQ rebuilt for around 350€. They cut the TQ open, replace the disc and then weld it back together.
The clutch like disc in TQ goes bad over time, usually impellers are good.
Are you certain the TQ you got was correct for your vehicle? It could also be a badly rebuilt TQ converter that's the issue. ZF TQ-s have a certain preload on the TQ (Yes it is always slippin) If it's too high this could be the issue but this is the problem of the manufacturer.

Of course your issue could also be caused by bad solenoid valves or valvebody.
You should also replace the rubber seals that sit between valvebody and the transmission, they do not cost much, maybe total max 50$, I can get ZF for cheaper than that.

From your symptoms after you replaced the TQ i would presume that your TQ was locked more than it needed to be.

Since without diagnostics all we can do here is speculate, i would bet bad TQ without more information. Otherwise you would have probably faults in EGS and i haven't seen valvebodys go bad like this.

Hi Barf,

Firstly, thank you for your response and apologies for the delayed reply. I had a lot of unplanned events to deal with recently that overwhelmed my life.

I want to clarify that £1600 was the total amount I spent for everything, which included one attempt at a gearbox service that did not improve the issue at all, then a second kit and fluid as the one they had just changed was contaminated with metal shavings, plus labor and a rebuilt torque converter. The rebuilt torque converter cost me £600 and they did it exactly the way you described here.

Now to the interesting part: I used realoem to check what gearbox I have to find the correct rebuilt TC. After querying for the part, based on what realoem says (link with my VIN: https://www.realoem.com/bmw/enUS/select?vin=VD91218), I needed a TC for 6HP26. The seller checked on their side and said I definitely have 6HP28 and sold me a TC for that gearbox.

As previously mentioned, it was fine for the first 2 days, after which the issues started coming back.

Today, I am still at the same point, to be honest. During the month that I was inactive, I have fixed all the errors by replacing glow plugs, control module and new throttle body, so these are all gone. I then added 2 tubes of LUBEGARD Instant Shudder Fixx, which actually made the issue completely go away for about 2 weeks. Then, it slowly started coming back to the point where it is worse than in the video shown above. The RPM jumps are more significant, mostly when going uphill or under light load/throttle. Sometimes the RPM doesn't fluctuate, but the car starts juddering randomly and then stops randomly as well. As soon as you step down on the accelerator pedal, it goes away.

I should mention another thing that I noticed: when I am braking to a stop, the harsher/quicker I brake, the more jerky, juddery, and pronounced the downshifting is.

I really don't know what to do. Do you think I should reach out and claim that the torque converter I received is bad? It has a 2-year warranty. I just don't want to pay yet again for a new kit and labor for the TC if it is, in fact, a bad gearbox..

[MidWillamette335d]

Originally Posted by barf

Since without diagnostics all we can do here is speculate, i would bet bad TQ without more information. Otherwise you would have probably faults in EGS and i haven't seen valvebodys go bad like this.

Sorry bout your luck, hope you get it sorted. Yeah, the no faults in the EGS kinda made me initially rule out solenoids since they should be throwing codes under these conditions if they're on their way out. Not sure if there if there is a visual check (probably is) you can do to your tranny to rule out one or the other if unsure, tho I'd imagine the tranny guy is getting the right part. If you haven't gotten XHP get that for android (and cable or wifi) and check your fill pressures and times, you can do that for free without a license. Maybe your mechanic has the tools to do it for you? If they're super out of whack your solenoids might be trying to compensate for worn out components causing your issues. Good luck whatever you path you take...

[barf]

Realoem displays all gearboxes as 6HP26 even if they are 6HP28.
Your Torque converter is V102 and this is what they should have sold.