535d turbo problem
Discussion
My 535d would appear to have turned into a single turbo 
; it's a dog below 2500 rpm but seems OK after that. It's as though the small turbo's wastegate is stuck open and not generating any boost. No funny noises, smoke oil, leaks or warning lights, just a slug of a car at low rpms. And since the gearbox software expects big torque at low rpms it doesn't downshift unless you just about floor the throttle.
; it's a dog below 2500 rpm but seems OK after that. It's as though the small turbo's wastegate is stuck open and not generating any boost. No funny noises, smoke oil, leaks or warning lights, just a slug of a car at low rpms. And since the gearbox software expects big torque at low rpms it doesn't downshift unless you just about floor the throttle.tbh i'm not sure if that wasn't a bit of 'speil' from the girl on the service desk, but I get the impression it wasn't a major problem.
In fact, when mine went (I heard a "Bang" as I reversed (slowly) out of a parking space and it was like this for the rest of the day. Called BMW assist who said it was safe to drive and was booked into local dealer the next day. When I got up the next day to take it in it was all working fine again! Could be a stuck wastegate I suppose?
No idea on cost etc as it was under warranty, but all done in a day and no specific parts ordered I dont think.
In fact, when mine went (I heard a "Bang" as I reversed (slowly) out of a parking space and it was like this for the rest of the day. Called BMW assist who said it was safe to drive and was booked into local dealer the next day. When I got up the next day to take it in it was all working fine again! Could be a stuck wastegate I suppose?
No idea on cost etc as it was under warranty, but all done in a day and no specific parts ordered I dont think.
In reading up on the operation of the 535d sequential turbos it would appear that all intake air passes through both turbos, first through the large one and then the small one. There's no wastegate on the small turbo, only on the large one. A computer controlled valve distributes the flow of exhaust gases between the two turbos; I guess this is effectively the wastegate for the small turbo. I find it interesting that all air flows through the small turbo; I would have thought that the compressor wheel would add significant resistance.
So my issue sounds like it might be one of the exhaust distribution valve being stuck in one position.
So my issue sounds like it might be one of the exhaust distribution valve being stuck in one position.
Just under 50K and standard.
BMW's answer is that as there are no codes or other apparent symptoms it's OK to drive until they have time to look at it. And have a loan car available. 11 Feb!
Here's a good cutaway of the turbo system
And I was wrong with what I posted earlier; when the large turbo is at full boost inlet air no longer flows through the small turbo.
So guessing some more; perhaps the flap that allows air to bypass the small turbo is stuck open.
BMW's answer is that as there are no codes or other apparent symptoms it's OK to drive until they have time to look at it. And have a loan car available. 11 Feb!
Here's a good cutaway of the turbo system
And I was wrong with what I posted earlier; when the large turbo is at full boost inlet air no longer flows through the small turbo.
So guessing some more; perhaps the flap that allows air to bypass the small turbo is stuck open.
phelix said:
No.
Just kidding. Happy to! It's still under warranty so it shouldn't be too painful.
LOLJust kidding. Happy to! It's still under warranty so it shouldn't be too painful.
There was a 535d turbo problem on bmwland and the guy was asking advice etc, as it was headlined '535d Twin Turbos blown', even though BMW themselves hadnt had a chance to diagnose it, and of course all the 535d Kickers were having a heyday about reliability and 'i told you so', BUT the o/p never bothered updating us as to what the problem turned out to be....
phelix said:
I posted in that thread in Sept and the original poster hasn't used the forum since or had the common courtesy to reply to the many queries about where things ended. 
I won't do what he did!
Yeah the whole point of forums is to learn from common experience, as opposed to get all the ideas as to what may have happened to the car and how to deal with BMW on it, then feck off into the great blue yonder like that bloke did. I won't do what he did!Some people eh?
Tis sorted. I took the airbox out to get a good look at the arrangement of the turbos and the various flaps and noticed that the vacuum line that controls the exhaust distribution valve was badly chafed where it runs across a sharpish corner. I couldn't get a replacement piece before the local dealer closed so shortened and re-routed it and put everything back together. All's back to how it was before. 
Edited by phelix on Saturday 26th January 18:44
phelix said:
Tis sorted. I took the airbox out to get a good look at the arrangement of the turbos and the various flaps and noticed that the vacuum line that controls the exhaust distribution valve was badly chafed where it runs across a sharpish corner. I couldn't get a replacement piece before the local dealer closed so shortened and re-routed it and put everything back together. All's back to how it was before.
Edited by phelix on Saturday 26th January 18:44
smartie said:
mine did that!
Into BMW for an afternoon appartantly it was " a hose issue"!
Sounds familiar.Into BMW for an afternoon appartantly it was " a hose issue"!
Regards
Chris
I guess I spoke a bit too soon. I replaced item #13 noted in http://www.realoem.com/bmw/showparts.do?model=NJ92... because it was badly chafed.
When I did so I noticed that the hose going into #7 was dislodged but figured I had dislodged it during my investigations so just reconnected it. Today I had the same problem occur and the same hose was dislodged. It appears to have shrunk with time and is barely long enough. So it needs replacement as well.
The hoses all have braided fibre covers and the covers crumble quite easily. I can well imagine more of these hoses will need replacement over time.
When I did so I noticed that the hose going into #7 was dislodged but figured I had dislodged it during my investigations so just reconnected it. Today I had the same problem occur and the same hose was dislodged. It appears to have shrunk with time and is barely long enough. So it needs replacement as well.
The hoses all have braided fibre covers and the covers crumble quite easily. I can well imagine more of these hoses will need replacement over time.
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