Secondary cats removed

Hubblyking

Honorary ///Member
Hi guys,after removing my secondary cats I see smoke from my exhaust and smell burning oil.It only smokes when i stop(sometimes).she still pulls strong,could it be my turbos are busy going or do I need to fit a oil catch can.pls help:cry:
 

///Shaun

Banned
Hubblyking said:
Hi guys,after removing my secondary cats I see smoke from my exhaust and smell burning oil.It only smokes when i stop(sometimes).she still pulls strong,could it be my turbos are busy going or do I need to fit a oil catch can.pls help:cry:


Dont stress dude it sounds about right. After a few days of driving it will go away. (Its like a whole lot of white smoke coming out at standstill creating the illusion that your turbos are gone.)

Its OIL that has been sitting that has entered your exhaust.Mine did the same but after two minutes of idling mine was gone, I know of other owners that experienced the same , all depends on the amount of oil that has entered into the turbo area.

Your Turbos are fine mate. For future mods OIL catch cans works nicely and also keep in mind ECU is adapting to having no secondary cats.

:thumbs:
 

Hubblyking

Honorary ///Member
///Shaun said:
Hubblyking said:
Hi guys,after removing my secondary cats I see smoke from my exhaust and smell burning oil.It only smokes when i stop(sometimes).she still pulls strong,could it be my turbos are busy going or do I need to fit a oil catch can.pls help:cry:


Dont stress dude it sounds about right. After a few days of driving it will go away. (Its like a whole lot of white smoke coming out at standstill creating the illusion that your turbos are gone.)

Its OIL that has been sitting that has entered your exhaust.Mine did the same but after two minutes of idling mine was gone, I know of other owners that experienced the same , all depends on the amount of oil that has entered into the turbo area.

Your Turbos are fine mate. For future mods OIL catch cans works nicely and also keep in mind ECU is adapting to having no secondary cats.

:thumbs:
Thanks Shaun,you giving me hope again .I will just drive her and see what happens.Do you know if there's gains on secondary cat removal?the torque and the throttle feels different .:thumbs:
 

///Shaun

Banned
Hubblyking said:
Thanks Shaun,you giving me hope again .I will just drive her and see what happens.Do you know if there's gains on secondary cat removal?the torque and the throttle feels different .:thumbs:


No probs mate. Difficult for me to say as I did DPs and secondary cats removal all at the same time , i just know car felt a whole lot better.


netercol said:
how does the ecu know the secondary cats are gone?

Airflow exit will differ and send different readings to probe on DP. Well this is my guess work.
 

Hubblyking

Honorary ///Member
62000kms -actually got out the exhaust and it smells rich, but in the cabin I smell oil.I checked the ecu and shows one sensor behind cats doesn't respond
 

Twinz

Forum - Support
Staff member
1. Do you have still have the primary cats?

2. The secondary cats are the filters. So if you remove them their is nothing "filtering" the muck. It should clear after some run in.

3. But turbos, oil lines going bad are also probable.
 
Hubblyking said:
Hi guys,after removing my secondary cats I see smoke from my exhaust and smell burning oil.It only smokes when i stop(sometimes).she still pulls strong,could it be my turbos are busy going or do I need to fit a oil catch can.pls help:cry:

Sorry for the off topic comment but, Wow, those Alpina mags look toooooo nice on that ride!:praise::praise::praise::praise::praise::inlove:
 

Hubblyking

Honorary ///Member
Iv'e read a few threads about smoke,and read about the pcv .did anyone experience that after going cat less ?
 

Hubblyking

Honorary ///Member
On the 5 forum a guy had similar issues like mine,took he's car to be checked and found that the pcv valve was stuck open and that caused the smoke.i will have to check what that is?.some people puts the secondary cats back then the issue is sorted .
 

netercol

New member
in the case of a e90 diesel, as i assume yours is..

the first cat or pre-cat is incorporated in the dpf , its purpose is to warm up fast and control startup emissions.

the second or primary cat is the bigger one that has more capacity, but heats up slower.

the lambda sensors after the cats will tell the ecu that they are missing, or that something else is wrong. you should have cat foolers in place to fool the ecu, the ecu will not adapt to a missing or non functional cat.

white smoke aka burning oil, can be caused by oil entering through the intake, via the breather (pcv), or compressor side of the turbo, or engine itself via valvestem seals or piston rings.

futher it can be from the exhaust side of the turbo, where a worn turbine seal might be letting oil through due to less backpressure (due to removal of the cat's restriction)
 

Hubblyking

Honorary ///Member
netercol said:
all the same except you have no dpf

Thanks, what would u suggest must I put the cats back or drive and see what happens.Forgot to mention I've got cat foolers.
 

M3_devil

Member
Been doing some reading on N54 forum and it would appear that it is a common problem once the 2nd decats are removed.

The problem only occurs on deceleration and mostly from turbo on passenger side for SA cars.

They mentioned that if car is put in neutral before stopping like at 1500rpm then smoke is not so severe. Will give it a try tonight.

My car also fully decatted, people probably thinking, that ou's motor has gone:rollsmile:
 
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