Smoke trails & oil residue in tail pipe.

[EM58NDS 135i]

Ok, so here is how the story goes. I bought my N54 135i in April last year. It's been great apart from a failed water pump. So about 5 months ago i fitted an N55 catless midpipe. All was good, except i then started to notice greyish trails of smoke under deceleration and stop/start driving. It wasn't happening everyday, so i thought nothing of it.

Yesterday, i went fully catless with some AA downpipes. The car feels and sounds great, spools up fast and goes as well as can be expected. BUT, now i am getting alot more grey smoke trails from the exhaust. The amount has literally doubled since going fully catless and it stinks of oil.

I took this photo after a 25 minute journey, with afew hard pulls.



Oil consumption is about 1ltr every 1500 miles. Is this too much? OFHG is leaking, but i doubt it is resposible for the oil blow by in the exhaust?

Car has 45k miles, no tune and full BMW service history.

[FactorX81]

1ltr every 1500mi sounds like a lot. My car uses 1ltr in about 6-7k right about when I change the oil I get the +1 indicator. Looks like turbo seals

[EM58NDS 135i]

Is this because of the lack of back pressure since i removed the cats?

http://www.turbodynamics.co.uk/techn...haust-systems/

[Grinchxvx]

Originally Posted by EM58NDS 135i

Is this because of the lack of back pressure since i removed the cats?

http://www.turbodynamics.co.uk/techn...haust-systems/

I think that's a possibility but think About this: there are tons of people who run Catless DP, berk race mids and axle back which is full Catless and don't have smoking cars. I think older/aging turbos are the ones who have issues. I can't see turbo seals not sealing because of a certain amount of back pressure.

[EM58NDS 135i]

Having done some online research, I have read through various forums with guys with N54's and less than 10k miles getting very smokey exhausts from going catless. The only cure is to refit the mids or DP's it seems.

[Grinchxvx]

Weird, there's so many people who run full Catless even with rattling turbos and don't have this problem.

[saace7]

Idk if you have worn parts BUT maybe try changing your oil type?


I was running the recommended BMW before they changed to this "Twin power" oil and burning oil anytime i ran it hard for over 30 minutes or so. Would consume an entire liter by the end of my oil change. I did this once, then changed the oil to Motul 8100 that is BMW LL01 and API SN.

Turnermotorsports is the only company I found that sells motul 8100 that is 5w-40 BMWLL01 (for the USA, BMWLL04 for other countries) and API SN. I went with 40w because it will get HOT down here in the south.

This oil is designed specifically for our engine type. I am a firm believer in this MOTUL. Since the oil change I have been to the drag strip and numerous hour or longer hard spirited drives and havn't burnt a single drop in 1500 miles. My oil temp hasn't gone pass 245 while driving in the hardest conditions and I still have stock oil cooler.

I have not tried the new BMW oil and probably will not even though it is $3 bucks less a liter.

I don't know if it will help your situation but it is food for thought.

[EM58NDS 135i]

Weightier oil may help, but TBH, i think the turbo seals are going bad...

[Pig Farmer]

That oil looks really clean, and did you wipe down the tips before taking the picture? I'm not saying you don't have an issue, I'm just wondering how the oil showed up with the tips that clean? My tips get soot within a couple miles of driving.

[EM58NDS 135i]

The exhaust is new. I wiped the tips before going for a drive, and that was the result after 20-30 mins.

[Aquila1]

Originally Posted by EM58NDS 135i

Weightier oil may help, but TBH, i think the turbo seals are going bad...

Just want to know if this was ever resolved. Did it end up being turbos or did you re-align the downpipes? Having the same exact problem.