[Andrewah05]

Hey all,
Few years ago I posted a thread about having a p0174 lean code (bank 2) and Catalyst system code too lean (p0498 I believe). Ended up getting cats replaced under emissions warranty, car was also stock. 3 years and now it happened again, the rotten egg smell and the same lean codes. Only difference was I had a Cobb for a 6 months and no issues but a month after I took it off the codes came up on and off until they finally stayed. Not sure if they are related. Is there a pre-existing issue with the car that is causing these cats to fail or am I just an unlucky mf? I think i'm also shit out of luck when it comes to warranty because it was over two years ago and Ontario BMW dealers aren't the biggest fans of good willing or even attempting to speak with BMWNA about it lol. Plan is too go catless but i'd like to try and figure out the issue if there is any with the cats failing. Thanks for reading.

[Welcome to NBA Jam]

It seems like something is killing your catalytic converters. They should last a very very long time. Do you have any excessive oil consumption or unburned fuel entering your exhaust?

[Andrewah05]

No obvious signs of excess oil consumption and not sure about the fuel, maybe leaky injectors. My gas mileage is utter shit however, even without my Cobb.

[Welcome to NBA Jam]

How bad is it, and would you say it's unusually low or a function of your foot? If it's unusually low, start there with the fuel. Unburned fuel can detonate in the catalyst and ruin it over time.

[07lilredwagon]

get it scanned. A lean condition could be from air entering the system somewhere, a faulty O2 sensor, bad injectors, ect...ect...but you wont know unless you read codes....have you had it checked?

JP

[Indyeah]

Cats dying twice is a sign that your cats are not the problem. Stop replacing them until you find out what is killing them.

[Andrewah05]

15mpg, I always assumed it was my foot. What causes the excess fuel in the cats?

[tlow98]

Driving routine? I get 15mog in the city. My kitties still purr

[1QuikWS6]

Don't know how old your car is, but Emissions components are warrantied way past regular warranty...

But you should definitely check for the reason they are crapping out - I have only ever had to replace a cat on one car out of tons I have owned & that was a GM - cat was plugged & glowed red hot when car was running

[robthewrench]

Originally Posted by Andrewah05

15mpg, I always assumed it was my foot. What causes the excess fuel in the cats?

You are getting un-burned fuel into the exhaust. This is killing your cats.

Possible sources:
- Leaking fuel injectors
- Bad custom tune / engine control
- Bad MAF sensor or O2 sensor giving bad info about amount of available air

[STR8-6IX]

excess fuel is definitely killing your cats.

dont bother with a new one, just get a downpipe. be sure to also delete your secondary cats or they will clog.

[Indyeah]

Originally Posted by 6IX-F10-N52

excess fuel is definitely killing your cats.

dont bother with a new one, just get a downpipe. be sure to also delete your secondary cats or they will clog.

No cats no problem

[STR8-6IX]

Originally Posted by Indyeah

No cats no problem

lol... I know right.

I also want to release my inner fuckboy and redline it past pedestrians and cause noise/smell complaints with a set of headers. I already have my secondaries deleted and a magnaflow muffler, but not loud enough

[Andrewah05]

I did have my cobb on but sold it, that's when stuff started happening do I need a reflash or something you guys think? I'm leaning towards injectors since I have the rough idle and I replaced plugs, coils, and did carbon cleaning about 30am ago. Are bank 2 injectors 123? I did replace 2,4,5,6 under warranty one and three are original from day 1. I thought n54s didn't have a MAF. Thanks again for the help, got some direction now of how to proceed. Anything tips on anything I can check at home before going to indy?

[STR8-6IX]

Originally Posted by Andrewah05

I did have my cobb on but sold it, that's when stuff started happening do I need a reflash or something you guys think? I'm leaning towards injectors since I have the rough idle and I replaced plugs, coils, and did carbon cleaning about 30am ago. Are bank 2 injectors 123? I did replace 2,4,5,6 under warranty one and three are original from day 1. I thought n54s didn't have a MAF. Thanks again for the help, got some direction now of how to proceed. Anything tips on anything I can check at home before going to indy?

this has nothing to do with your cobb.

Intake air leaks
[B] O2 sensors [B]
Ignition misfiring
Faulty fuel injectors
Exhaust gas leaks
Incorrect fuel pressure
Lack of fuel
Faulty Mass Air Flow (MAF) sensor
[B]
Incorrect Positive Crankcase Ventilation (PCV) hose connection

also look into the CCV and EVAP systems. check to make sure fuel pump is working okay. change your air filter

[Andrewah05]

Originally Posted by 6IX-F10-N52

this has nothing to do with your cobb.

Intake air leaks
[B] O2 sensors [B]
Ignition misfiring
Faulty fuel injectors
Exhaust gas leaks
Incorrect fuel pressure
Lack of fuel
Faulty Mass Air Flow (MAF) sensor
[B]
Incorrect Positive Crankcase Ventilation (PCV) hose connection

also look into the CCV and EVAP systems. check to make sure fuel pump is working okay. change your air filter

Sounds good man, will probably hook up INPA and take a look once I fix my Win 7 laptop. N54 doesn't have a MAF sensor, N52's do though. And yeah, not going to replace them, just going to get catless downpipes, just did emissions test this year so I shouldn't have to worry for a few years .

[STR8-6IX]

Originally Posted by Andrewah05

Sounds good man, will probably hook up INPA and take a look once I fix my Win 7 laptop. N54 doesn't have a MAF sensor, N52's do though. And yeah, not going to replace them, just going to get catless downpipes, just did emissions test this year so I shouldn't have to worry for a few years .

definitely make sure you get your engine running OK as soon as possible dude. you'll get back all that money through fuel savings anyways. ruining two cats within a matter of a couple years.. you know its running like complete shit,

[ObsidianX]

Do you have any mods for your air intake? Are you using a K&N air filter?

My gut is the mass air flow sensor, but you'll need to verify there is no unmetered air entering the system first.

[Andrewah05]

Originally Posted by ObsidianX

Do you have any mods for your air intake? Are you using a K&N air filter?

My gut is the mass air flow sensor, but you'll need to verify there is no unmetered air entering the system first.

Dual cones bro