[Brucey335i]

Hey guys I've noticed since I've gone CDP and cut my secondary cat out I've noticed some smoke... only started once i did the downpipe... when i removed the old parts there wasn't any oil inside of the downpipes... same with the secondary cat... no oil inside that either.. once the car warms up to operating temp 237-250 ish there is no smoke/ very minimal. It's only on cold starts and it the smoking will subside if i drive... if i let the car warm up like i usually do that's when i see the smoke.. if i just get in and go it doesn't smoke..

[Brucey335i]

I don't believe it's the turbo seals... (well I'm just telling myself that cause that's worst case..) just didn't know if there's another way i can go about trouble shooting this... i felt if it was the turbo seals it would be constantly pushing smoke.. even during acceleration in which it isn't

[JM98]

Welcome to the club lol. Most high mileage N54s have smoking issues when you remove the cats as they are not there to mask it.

Do your turbos hold boost well to redline? If so I wouldnt worry about it too much.

Smoke on deceleration is usually turbo seals but can sometimes be PCV or valve cover. It's more embarrassing than anything else.

[Rob09msport]

Could be cracked valve covers or cam ledges , valve seals etc it's good that only happens on cold starts . If no other symptoms then you should be good

[Brucey335i]

Originally Posted by JM98

Welcome to the club lol. Most high mileage N54s have smoking issues when you remove the cats as they are not there to mask it.

Do your turbos hold boost well to redline? If so I wouldnt worry about it too much.

Smoke on deceleration is usually turbo seals but can sometimes be PCV or valve cover. It's more embarrassing than anything else.

Turbos hold boost fine

[ian3924]

I've got the same issue as you and I have new turbos, rb pcv, catless dp, and inlets. If I drive and shut the car off for 30 mins go to the store and come back, within 5 minutes of idling it'll start to smoke for 2-3 minutes or until I drive for a bit then no more smoke. It's pretty annoying im hoping an occ will help.

[WoodE30]

Originally Posted by Brucey335i

Hey guys I've noticed since I've gone CDP and cut my secondary cat out I've noticed some smoke... only started once i did the downpipe... when i removed the old parts there wasn't any oil inside of the downpipes... same with the secondary cat... no oil inside that either.. once the car warms up to operating temp 237-250 ish there is no smoke/ very minimal. It's only on cold starts and it the smoking will subside if i drive... if i let the car warm up like i usually do that's when i see the smoke.. if i just get in and go it doesn't smoke..

Kind of sounds like valve guide seals, but we don’t really have an issue with them but that doesn’t mean that’s not it. Best way to check for valve guide seals, let the car idle for 5-10 minutes then with car in park floor the gas, if a bunch of smoke, good possibility it’s valve guide seals especially if you know your injectors are good.

[Brucey335i]

Originally Posted by WoodE30

Kind of sounds like valve guide seals, but we don’t really have an issue with them but that doesn’t mean that’s not it. Best way to check for valve guide seals, let the car idle for 5-10 minutes then with car in park floor the gas, if a bunch of smoke, good possibility it’s valve guide seals especially if you know your injectors are good.

Sooooo if i idle and let the car warm up to the normal temp of 237 the car will start to smoke around 180 give it take... if i floor it in park. It'll push the smoke out and slowly subside till it hits operating temps... if i just cold start and drive the car the smoke is so minimal it isn't noticable.... once the car is at normal operating temps it doesn't smoke at idle what so ever.. i can leave it sitting for 20 minutes at idle and no smoke once she's warm

[WoodE30]

Originally Posted by Brucey335i

Sooooo if i idle and let the car warm up to the normal temp of 237 the car will start to smoke around 180 give it take... if i floor it in park. It'll push the smoke out and slowly subside till it hits operating temps... if i just cold start and drive the car the smoke is so minimal it isn't noticable.... once the car is at normal operating temps it doesn't smoke at idle what so ever.. i can leave it sitting for 20 minutes at idle and no smoke once she's warm

what color is the smoke? Blue, black, white? Maybe pull the spark plugs out, see what they look like and post a picture.

[Brucey335i]

Originally Posted by WoodE30

what color is the smoke? Blue, black, white? Maybe pull the spark plugs out, see what they look like and post a picture.

White smoke

[WoodE30]

Originally Posted by Brucey335i

White smoke

Just to clarify, smoke out of the exhaust right, not like under the hood?

[WoodE30]

Originally Posted by Brucey335i

White smoke

Just to clarify, smoke out of the exhaust, not under hood?

[Brucey335i]

Originally Posted by WoodE30

Just to clarify, smoke out of the exhaust right, not like under the hood?

Correct exhaust one side only to be specific. I've checked both turbos less then a week ago

[arkie6]

White = water vapor
Blue/Grey = oil
Black = fuel

Water vapor is a normal byproduct of combustion and is normally visible on most cars in the fall/winter before the engine and exhaust system is fully warmed up. Is this what you are seeing? Is your coolant level going down or remaining steady? Get out and smell the "smoke". Does it smell sweet? That would be an indication that coolant is getting into the combustion chamber/exhaust.

[mweisdorfer]

Originally Posted by WoodE30

Kind of sounds like valve guide seals, but we don’t really have an issue with them but that doesn’t mean that’s not it. Best way to check for valve guide seals, let the car idle for 5-10 minutes then with car in park floor the gas, if a bunch of smoke, good possibility it’s valve guide seals especially if you know your injectors are good.

That's it the smoke has a blueish tint

[mweisdorfer]

If wastegates are not closing the right way, it can cause smoke issues with catless downpipes.

[Brucey335i]

Originally Posted by mweisdorfer

If wastegates are not closing the right way, it can cause smoke issues with catless downpipes.

Wouldn't that be constant though rather then intermittent

[mweisdorfer]

Originally Posted by Brucey335i

Wouldn't that be constant though rather then intermittent

Agreed. I know when I go to stage 0, I have constant smoke. When I go stage 1 or 2, no smoke at all.

I have OEM turbos with 167,000 miles on them.

[Brucey335i]

Originally Posted by mweisdorfer

Agreed. I know when I go to stage 0, I have constant smoke. When I go stage 1 or 2, no smoke at all.

I have OEM turbos with 167,000 miles on them.

I'm stage 2 + full bolt on. It's intermittent if i get in and go it's very minimal... once car reaches ambient temps it doesn't smoke at all... very weird

[mweisdorfer]

Originally Posted by Brucey335i

I'm stage 2 + full bolt on. It's intermittent if i get in and go it's very minimal... once car reaches ambient temps it doesn't smoke at all... very weird

I have upgraded :

FMIC - 5" stepped
CAI air box
Inlets
Outlets
Catless downpipes
Secondary Cat Delete

I don't have the wastegate option ticked in MHD

I do have the wastegates tightened down

No smoke

[335iN54enthusiast]

Smoking issues when catless can be misleading and time consuming to diagnose. Check out my smoking n54 you tube vid

[Hussain22]

Hello I own a bmw 335i n54 cat deleted and muffler deleted with about 100k miles with brand new turbos. My oil filter has been leaking for awhile which am not worried about but when my car is warmed up blue and white smoke comes out the exhaust only when am driving it twice a day for 3 seconds. The car runs perfect no check engine light etc but should I be worried about this smoke.