Unresolved smoking on Deceleration.

General.Massacre

Corporal
May 14, 2018
219
57
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2009 E92 335i DCT
Hello Everyone.
Its been a while since i been active here, and for all that missed me, im truly sorry... :D

anyways,

I have an issue on my E92 335i N54 in that its smoking when i decelerate, and at idle. no other time.
I have also noticed it happens when feathering the throttle in a cruising scenario is D mode, at low rpm, this sends me to the thought that my issue only happens in vacuum mode. just a thought.

So far i have done the following, in this order.

I have Chinese turbos, the car was smoking so i assume they stuffed out being chinese, and decided to have them rebuilt. so off they came and were sent in, the rebuilder is very well known here in Johannesburg, and has an incredible reputation. he asked me after stripping them down, why i sent them to him, as they were in great condition, only gripe was that the Thrust bearing has some slight premature wear, but he wouldnt call it alarming.
They were rebuilt, balanced on the VSR machine, and given a clean bill of health.
Got the car back, it seemed ok, but after a couple days. the smoking was back.

After tons of more research, i read that Valve Stem Seals have the very similar symptoms to turbo seals. and so i had the Car booked in for Valve Stems seals.
Got the car back and while going up the road on my way home i saw smoke again as i came to a stop. and its been like this ever since.

Ive also had another Brand new Valve cover with Gasket replaced. this came obviously with a new PCV valve, also didnt help, car still smoked, so that ruled out a cracked VCG, or PCV.
I then got my hands on an upgrade PCV valve. and again no cure.
I do not have an OCC, but, i dont believe this would assist my issue here, but, im open to trying it so will try obtain one at some piint just to rule it out.

I then conducted a compression test, and this passed, as i was worried that i have damaged rings.
Cyl1. 150psi
Cyl2. 150psi
Cyl3. 150psi
Cyl4. 140psi
Cyl5. 145psi
Cyl6. 150psi

I thought these values may be low, but i read on multiple threads that 150psi is the normal value to see, and a variance of around 10% is acceptable to deviate at another cylinder. can anyone confirm this?

Another point i need to conduct, is the Oil Return Lines. i still ahve the original lines, and they maybe clogged, or worn or whatever, as they have been through 3 turbo removals and refitments in my 2 1/2 years ownership. so they may be the culprit, however, i hold my breath till they get done, which im hoping will happen this thursday.


I have been speaking to 4 other N54 drivers in my area, and all there cars are doing the same thing, smoking on Decel.
1 has MMP 1K turbos,
1 is stock turbos
and the others are chinese hybrids like mine, so that rules out the fact that its shitty Chinese turbos, as the car is still performing great, just has the smoke and goes through oil reasonably fast.

besides the Oil Drains, im at a loss as to what this could be caused by.

Anyone had this before and cured it?

Thanks in advance guys.
 

tisdrew

Corporal
Jun 27, 2017
179
91
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09 335i 6MT
Sorry to say, but it's turbos 99% of the time. The turbo oil seals aren't doing their job and oil is getting into the exhaust and burning causing the smoke--hence the oil consumption. Get a different set of turbos -- your current turbos will make boost/power but they'll smoke like a chimney. I had this issue on both my stock turbos and my MMPs. You already seemed to have addressed the PCV but you may want to look into plugging the head ports if you're serious about it.

A) replace your turbos with new stockers or Pures
As a hacky fix until you can afford above, put all four cats back into place -- the honeycomb will help burn off the oil and prevent it from coming out the tail pipe as badly
 

Bnks334

Lieutenant
Dec 1, 2016
528
342
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New York
You named a bunch of Chinese turbos and then said "this rules out that it's the shitty Chinese turbos." Or, it proves they are shitty Chinese turbos (stock Mitsubishi and pretty well proven to be cheap crap) lol...

Do some actual diagnosis. Pull the downpipe. Check if there is oil in the downpipe (could be turbo or could be from engine). Then pull the turbo outlet. Check for oil (could be turbo or could be blow-by). Pull the catch can and PCV lines. Check for oil in the intake plenum (blow-by). And then if you can't see any clear indicator pull the entire turbofold on whatever bank the oil is coming from and check the exhaust ports and valves.

IRC, newtis has 140psi as the lower service limit for compression. Should actually be ~180psi or so on a used engine but there are lots of variables in testing this so most just say "just make sure all your numbers are close." High vacuum on decel will pull oil past worn rings and smoke. All the exhaust ports will be oily/black. Valve stem seals will show as oil coming down from the valve stems. The only way to see this is by removing the turbofold.

I've usually seen turbo smoke as either always or acceleration not really so much on decel.
 
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Milan

Sergeant
Dec 24, 2016
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jebi se
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your mom
You can try the other fixes but it almost always ends up being the turbos. Most people are in major denial about it but that's what it comes down to.

Double check your valve cover and flapper valve
 

RNM

Corporal
Jun 3, 2019
175
166
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My car was smoking like a chimney recently and once we pulled out the downpipes, it was evident that the rear turbo took a shit.
 

Torgus

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Nov 6, 2016
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Boston
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ACF 6466 E92 + METH
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135iTX

Corporal
Dec 1, 2017
115
70
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2009 135i
99% of the time its the turbos. Sorry bro, but denial wont help - pull the down pipes and see if theres oil, it's the easiest way to check the most obvious issue vs chasing around gaskets and valve stem seals.
 

General.Massacre

Corporal
May 14, 2018
219
57
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2009 E92 335i DCT
Thanks all.

Honestly yea im in denial and praying its not turbos again, coz that will be a blow, but, it does seem that most people report back the rear turbo always being the one to take a shit. any reason for that.
but i do agree, and ill make a plan to pull the Downpipes and have a look what the case is here.

That thread about the bent rod scares me, lol, but saying that, its not the first thread ive read where a car has passed compression and leakdown and has had to be rebuilt.

I will be checking the Oil drains, the Downpipes have to come off anyway, so will inspect turbos same time. then report back.
 

AUbeast86

Sergeant
Nov 6, 2016
302
298
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New Market, AL
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335i e92 6MT
Thanks all.

Honestly yea im in denial and praying its not turbos again, coz that will be a blow, but, it does seem that most people report back the rear turbo always being the one to take a shit. any reason for that.
but i do agree, and ill make a plan to pull the Downpipes and have a look what the case is here.

That thread about the bent rod scares me, lol, but saying that, its not the first thread ive read where a car has passed compression and leakdown and has had to be rebuilt.

I will be checking the Oil drains, the Downpipes have to come off anyway, so will inspect turbos same time. then report back.

Good luck man. I was in denial for about a year and as you can see from my bent rod post, I've been "troubleshooting" this POS for a very long time. I've been through it all, blown turbos (stock and back in the day RBs), failed exhaust valve stem seals, bad PCV, clogged oil drains and the ultimate kick in the dick, bent rods so I definitely feel your pain.
 
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General.Massacre

Corporal
May 14, 2018
219
57
0
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2009 E92 335i DCT
if its just a draining issue due to improper pcv then i would address it with this https://vadersolution.com/products/vader-solutions-n54-breather-system

very common ... if it isnt draining issue due to pcv then i would def swap out the turbos. any specific tail pipe has smoke or is it both?

My car was just dropped off this morning to check drains.

The smoke doesnt come out one specific pipe, i assume this is because of the X Pipe?
Once my Mechy has removed the DP's and the drains, we will know more, im praying its not turbos, but, no use speculating for now. its the waiting game, i should know in a matter of hours.

The Breather System i was actually watching your video yesterday. and im very interested, it will need to wait, but i do want the system.
 

General.Massacre

Corporal
May 14, 2018
219
57
0
Ride
2009 E92 335i DCT
So got feedback from my Mechy,
Oil Drains are fine, he showed me a video where the Front drain looked Kinked, but on removing it, and inspecting, it was actually fine.
Video >>>here<<<

However, there was alot of oil on the bottom of the rear silicone inlet. Suspect oil is pushing past the Compressor seal? is this possible. they were rebuilt about 3000km ago.

The inside of the turbos on the turbine side are bone dry and look good.
there is some play on the shafts, but marginal at best.

My turbo side Engine mount is absolutely toast though also.

So is this now safe to say that its the turbos that are well and truly my issue?

I do have the Rear Inlet pipe from the Flapper redirected and the inlet connection blanked off so there is no oil making its way from the valve cover into the rear inlet.
 
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135iTX

Corporal
Dec 1, 2017
115
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2009 135i
How much smoke are you getting? Honestly, as long as the turbos are boosting well you can say fuck it and keep driving the car as long the smoke is isnt too bad. My stock turbos smoke like a mfer on decel in gear, but they hold boost fine so ive just been running em for 2+years like this and shift into neutral when decelerating lol
 

General.Massacre

Corporal
May 14, 2018
219
57
0
Ride
2009 E92 335i DCT
How much smoke are you getting? Honestly, as long as the turbos are boosting well you can say fuck it and keep driving the car as long the smoke is isnt too bad. My stock turbos smoke like a mfer on decel in gear, but they hold boost fine so ive just been running em for 2+years like this and shift into neutral when decelerating lol
They smoke pretty bad on decel and then when idling after a push.
You switch to Neutral? I have DCT. Ive never thought of doing that to be honest.
 

General.Massacre

Corporal
May 14, 2018
219
57
0
Ride
2009 E92 335i DCT
Soooo, good morning Fellas.
I know its been 2 months i last spoke of this issue, and as some of you have stated and advised, yup, it was the turbos unfortunately.
As the car is my daily driver, and the fact that i had spent to have the turbos done previously and again for Vlave Stem seals, i need to wait to have the turbos removed,
I found a set of Stockers, purchased new cores, and reinstalled the OEM inlets, and the Stock turbos, along with the OEM downpipes.

Result: Smoke is gone. car drives fine.
On inspecting the Chinese hybrids, i found the rear turbo to be solid and fine, i asuume the oil on the underside of the rear inlet was due to my mechanic not fitting a clamp in place, so that would have allowed the oil breather tube to do its usual thing, but due to no clamp, the seepage came out the inlet and ran the underside.
The front turbo however, look good, but had some forward and back movement on the Turbine shaft. so this would be due to thrust (unbelievable as these turbos were supposed to have been freshly rebuilt with upgrade thrust bearings and collars, clearly i was taken for a ride).
So needless to say, it chewed up a seal.

Strange thing though, is that both turbos showed no signs of oil, or wetness around either of the wheels. and besides the usual oil mess from removing the drains/feed lines, there is no oil in, or on the turbos. they actually very clean.
Any idea on that, could oil vaporize quickly if the amount of oil is minimal enough to cause smoke on Decel, but not enough to show signs?

Thanks however to all involved in lending advice, i was in denial, but the work is done and the car is back to stock for the meantime till my finances recover.
Will be selling the Hybrid turbos as used for someone local to rebuild and enjoy, but for now i will enjoy my car stock.

Thanks