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      05-06-2021, 11:27 AM   #1
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2016 BMW 340i xDrive - White smoke from exhaust and fuel smell

Moderators: Please excuse my ignorance if this is in the wrong forum.

So I had my first BMW getting towed experience last night.

Backstory:
Two days ago I was idling my car for a while because it was 10pm and I had no lights and I wanted to detail my car while listening to the radio. I was detailing the interior I didn't touch anything under the hood. An hour and a half of idling perfectly fine it suddenly had a really rough idle, a screeching noise, and white smoke coming from the engine bay and exhaust. I let the car sit overnight and the next morning had my wife record while I turned it back on. It turned on fine no noise or smoke. I drove it to work and continued to monitor for misfires using Bimmerlink. I noticed one or two misfires on the way to and from work which is a 5 mile drive one way.

I installed my BMS catch can and continued to drive it for a couple of days with one or two misfires on the way to and from work. I decided to order a Vargas VTT B58 One Way Crankcase breather and install it. Right after the install of the one way crankcase breather I drove it to allow it to warm up and once it reached operating temp there was so much white smoke (only from the exhaust) I had to pull over and have it towed. When the tow truck showed up an hour later the car drove onto the flatbed fine and the smoke out of the exhaust was white but there wasnt a lot of it and then it went away. The car didn't seem to lack power, there is no check engine light and there are no codes.

I turn it back on to idle in my driveway and the white smoke is minimal on startup and then goes away. After a few minutes of idle it rough idles and starts to have white smoke from the exhaust so I shut it off. The engine bay and exhaust smell like fuel. I pulled a coil and checked if it had anything on it and it seemed clean. I remove the oil cap (which is now the crankcase breather) it looks clean inside. I remove both coolant tank caps and one tank (the larger) has two little droplets of oil in them while the other tank (smaller) has no oil. We remove the chargepipe and find trace amounts of oil in it.

Does anyone have insight? It would be greatly appreciated.

Edit: Mod List- BMS Catch Can modified to fit with stock intake, Vargas CTT One Way Crankcase Breather, Active Autowerke high flow downpipe, Exhaust Manifold Blanket, Turbo Blanket, Bootmod3 custom Cary Jordan Tune

Last edited by WrxToBeamerGuy; 05-06-2021 at 11:30 AM.. Reason: added mod list
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      05-06-2021, 11:54 AM   #2
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Any oil in the catch can? Did the exhaust smell like gas only for a few minutes after start or continuously? BM3 log the fuel rail pressure. Did you get any codes?
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      05-06-2021, 12:00 PM   #3
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Quote:
Originally Posted by BMWILUVU View Post
Any oil in the catch can? Did the exhaust smell like gas only for a few minutes after start or continuously? BM3 log the fuel rail pressure. Did you get any codes?
No oil in the catch can at all not even a drop. I can BM3 log the fuel rail pressure am I looking for a pressure spike or a pressure drop? I haven't run it for more than a few minutes since it starts rough idling and I'm afraid of causing damage by letting it idle longer.

edit: you asked if I got any codes. I ran an OBDII scanner after it happened and I had no codes.

Last edited by WrxToBeamerGuy; 05-06-2021 at 12:16 PM..
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      05-06-2021, 01:43 PM   #4
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Some of what you say doesn't quite line up. White smoke and fuel in exhaust smell at startup is normal but only lasts the first minute or less. If you smell it after coldstart procedure then I would be concerned. Fuel smell in the engine bay is not normal. This is why I asked if you have logs showing fuel rail drop. Are you sure you did not see grey smoke burning off the oil from the pcv from long idle since I don't think you had the catch can on when it happened correct?
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      05-06-2021, 02:28 PM   #5
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Quote:
Originally Posted by BMWILUVU View Post
Some of what you say doesn't quite line up. White smoke and fuel in exhaust smell at startup is normal but only lasts the first minute or less. If you smell it after coldstart procedure then I would be concerned. Fuel smell in the engine bay is not normal. This is why I asked if you have logs showing fuel rail drop. Are you sure you did not see grey smoke burning off the oil from the pcv from long idle since I don't think you had the catch can on when it happened correct?
Correct I didnt have the catch can on. It was a lot of smoke and maybe it was grey but it certainly started really rough idling a few minutes in. I'm wondering if an injector is stuck open and or if the turbo is leaking oil.
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      05-06-2021, 06:32 PM   #6
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Rip your PCV.
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      05-06-2021, 06:39 PM   #7
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Originally Posted by G.Newt View Post
Rip your PCV.
Yeah I'm torn. My buddy thinks we should just try replacing the pcv diaphragm.
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      05-06-2021, 08:08 PM   #8
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So first thing I would do is get rid of the Vargas one way crankcase breather. They have great products, I even run their GC turbo, but I heard many stories of breather causing white smoke out the exhaust, don't know the exact science behind the reasoning but no good. I even had the same smoke issue happen right after my install of the same breather and I just put my oil cap back on, was fine.

Second thing, regarding excessive fuel smell and white smoke out the exhaust, that could possibly be an injector. 2 weeks ago, one of my injectors got stuck open somehow. Car had really rough idle out of nowhere and had fuel coming out the exhaust with smoke due to the fuel flooding the cylinder head. As soon as I pulled plug #4 I smelled fuel and realized it was the injector. So I replaced the injector, of course did an oil change and all was good.

So I'd have them check for plugs/coils and injectors. And I'd also get an oil change if that's one of the problems, because if fuel got into your cylinder head, it will cause the oil to lower its viscosity (become thin) and it can cause scoring in the cylinders and engine internal issues.

Hope it all goes well, keep us updated
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      05-06-2021, 08:30 PM   #9
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Quote:
Originally Posted by WrxToBeamerGuy View Post
An hour and a half of idling perfectly fine
It's not a diesel. Don't do this.

Common theme, see here:
https://f30.bimmerpost.com/forums/sh....php?t=1812231
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      05-06-2021, 10:17 PM   #10
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Quote:
Originally Posted by Th3Walrus View Post
It's not a diesel. Don't do this.

Common theme, see here:
https://f30.bimmerpost.com/forums/sh....php?t=1812231
Yeah I was completely unaware that idling a car could have negative consequences like that. I'm thinking im being smart for not draining the battery but I was obviously wrong.

I read the thread you linked. Should I also buy this part to replace?
https://www.ebay.com/itm/Membrane-Va...EAAOSwOxVgACU6


update: Just ordered this
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

delivers this Sunday.

update2: It didn't come with the cap and for some reason I thought it would. I cant find the option to purchase the cap anywhere. I decided to buy a whole new PCV cover and all the specialty tools required to do the job, $850.

Last edited by WrxToBeamerGuy; 05-10-2021 at 09:10 AM..
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      05-06-2021, 10:19 PM   #11
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Quote:
Originally Posted by luca10 View Post
So first thing I would do is get rid of the Vargas one way crankcase breather. They have great products, I even run their GC turbo, but I heard many stories of breather causing white smoke out the exhaust, don't know the exact science behind the reasoning but no good. I even had the same smoke issue happen right after my install of the same breather and I just put my oil cap back on, was fine.

Second thing, regarding excessive fuel smell and white smoke out the exhaust, that could possibly be an injector. 2 weeks ago, one of my injectors got stuck open somehow. Car had really rough idle out of nowhere and had fuel coming out the exhaust with smoke due to the fuel flooding the cylinder head. As soon as I pulled plug #4 I smelled fuel and realized it was the injector. So I replaced the injector, of course did an oil change and all was good.

So I'd have them check for plugs/coils and injectors. And I'd also get an oil change if that's one of the problems, because if fuel got into your cylinder head, it will cause the oil to lower its viscosity (become thin) and it can cause scoring in the cylinders and engine internal issues.

Hope it all goes well, keep us updated
Thank you for your input! Today I got everything ready to pull the plugs but didn't pull them just yet since I wanted to clean up the dirt in the engine bay first. I'll follow this advice to the tee and report back before the end of the weekend. If only I didn't have work and had more time to work on the car
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      05-07-2021, 03:20 AM   #12
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Quote:
Originally Posted by Th3Walrus View Post
Quote:
Originally Posted by WrxToBeamerGuy View Post
An hour and a half of idling perfectly fine
It's not a diesel. Don't do this.

Common theme, see here:
https://f30.bimmerpost.com/forums/sh....php?t=1812231
So you're saying our 50-60k+ BMW's wouldn't make it through a drive-in movie? You should be able to idle your car for as long as you want.
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      05-07-2021, 07:21 AM   #13
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Quote:
Originally Posted by G.Newt View Post
Quote:
Originally Posted by Th3Walrus View Post
Quote:
Originally Posted by WrxToBeamerGuy View Post
An hour and a half of idling perfectly fine
It's not a diesel. Don't do this.

Common theme, see here:
https://f30.bimmerpost.com/forums/sh....php?t=1812231
So you're saying our 50-60k+ BMW's wouldn't make it through a drive-in movie? You should be able to idle your car for as long as you want.
You should be doesn't mean you can't just not advised as lots of people has issues when letting idle more than 5 or so minutes with the diaphragm.
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      05-07-2021, 12:42 PM   #14
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Quote:
Originally Posted by luca10 View Post
So first thing I would do is get rid of the Vargas one way crankcase breather. They have great products, I even run their GC turbo, but I heard many stories of breather causing white smoke out the exhaust, don't know the exact science behind the reasoning but no good. I even had the same smoke issue happen right after my install of the same breather and I just put my oil cap back on, was fine.

Second thing, regarding excessive fuel smell and white smoke out the exhaust, that could possibly be an injector. 2 weeks ago, one of my injectors got stuck open somehow. Car had really rough idle out of nowhere and had fuel coming out the exhaust with smoke due to the fuel flooding the cylinder head. As soon as I pulled plug #4 I smelled fuel and realized it was the injector. So I replaced the injector, of course did an oil change and all was good.

So I'd have them check for plugs/coils and injectors. And I'd also get an oil change if that's one of the problems, because if fuel got into your cylinder head, it will cause the oil to lower its viscosity (become thin) and it can cause scoring in the cylinders and engine internal issues.

Hope it all goes well, keep us updated
Where are you hearing about the VTT breather causing exhaust smoke?
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      05-08-2021, 08:15 AM   #15
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Quote:
Originally Posted by BMWILUVU View Post
Quote:
Originally Posted by luca10 View Post
So first thing I would do is get rid of the Vargas one way crankcase breather. They have great products, I even run their GC turbo, but I heard many stories of breather causing white smoke out the exhaust, don't know the exact science behind the reasoning but no good. I even had the same smoke issue happen right after my install of the same breather and I just put my oil cap back on, was fine.

Second thing, regarding excessive fuel smell and white smoke out the exhaust, that could possibly be an injector. 2 weeks ago, one of my injectors got stuck open somehow. Car had really rough idle out of nowhere and had fuel coming out the exhaust with smoke due to the fuel flooding the cylinder head. As soon as I pulled plug #4 I smelled fuel and realized it was the injector. So I replaced the injector, of course did an oil change and all was good.

So I'd have them check for plugs/coils and injectors. And I'd also get an oil change if that's one of the problems, because if fuel got into your cylinder head, it will cause the oil to lower its viscosity (become thin) and it can cause scoring in the cylinders and engine internal issues.

Hope it all goes well, keep us updated
Where are you hearing about the VTT breather causing exhaust smoke?
I can't remember where, I researched this a few months back after I saw white smoke coming from exhaust and heard that the breather is the problem. It's suggested to do a whole pcv upgrade or none at all
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      05-08-2021, 04:34 PM   #16
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Quote:
Originally Posted by G.Newt View Post
So you're saying our 50-60k+ BMW's wouldn't make it through a drive-in movie? You should be able to idle your car for as long as you want.
Why are you idling at a drive-in movie?
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      05-08-2021, 09:22 PM   #17
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Quote:
Originally Posted by Th3Walrus View Post
Why are you idling at a drive-in movie?
Depending on how far back you are, you wanna be able to tune-in via the FM station. Regardless, I should be able to idle my luxury German automobile for a couple of hours without issue.

Hell, in the winters, it used to take me 20-30 mins to brush all the snow off before I got my garage. What if you're stuck in traffic behind a major accident on the highway?

There are many scenarios where a car may sit/move very little for some extended periods of time while running. Anyone saying our cars shouldn't be able to do that..... lol. "Guys, the broken PCV while idling is a feature, not a bug!"
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      05-08-2021, 11:17 PM   #18
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Quote:
Originally Posted by G.Newt View Post
Depending on how far back you are, you wanna be able to tune-in via the FM station. Regardless, I should be able to idle my luxury German automobile for a couple of hours without issue.

Hell, in the winters, it used to take me 20-30 mins to brush all the snow off before I got my garage. What if you're stuck in traffic behind a major accident on the highway?

There are many scenarios where a car may sit/move very little for some extended periods of time while running. Anyone saying our cars shouldn't be able to do that..... lol. "Guys, the broken PCV while idling is a feature, not a bug!"
I completely agree with you Newt.
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      05-09-2021, 01:32 AM   #19
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The pcv failing whilst idling for a long time is unfortunately very common. It shouldn't do it but it does. BMW won't warranty cover this work normally so we are kinda stuck
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      05-09-2021, 01:56 AM   #20
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Quote:
Originally Posted by chris-c View Post
The pcv failing whilst idling for a long time is unfortunately very common. It shouldn't do it but it does. BMW won't warranty cover this work normally so we are kinda stuck
If it's just the diaphragm, it's a $40 part. I might even keep one in the car just in case so it doesn't leave me stranded.
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      05-09-2021, 07:33 AM   #21
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Quote:
Originally Posted by G.Newt View Post
Depending on how far back you are, you wanna be able to tune-in via the FM station.
Why do you need to idle to tune in to the FM station?
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      05-09-2021, 12:42 PM   #22
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Quote:
Originally Posted by Th3Walrus View Post
Why do you need to idle to tune in to the FM station?
What are you trying to accomplish?
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