[haus]

Originally Posted by reidnez

I was just wondering if there was a common, known problem with these cars that I should check into first. I'm going to take it to the shop I trust and have them do some investigation. Thanks guys!

Check the underside of your intake boot carefully. If it's original there is a 2-3" crack in it allowing unmetered air into the engine. I'm surprised you're not throwing any codes with numbers like that. You tested codes with a Peake scan tool and not some random OBDII reader at a non-BMW shop, right? My Peake reader came up with a TPS code that did not appear in Torque.

[englishtom1596q]

maybe if you had a code for o2 sensor and drove it for awhile running rich you killed your cats. and now you've fixed the o2 sensor so your not getting codes but the cats aren't doing they're job. and our cars would no way pass smog without cats, from my understanding our cars are not that efficient. however on the s54 i have heard of people passing smog with no cats due to good tuning.

[reidnez]

Originally Posted by haus

Check the underside of your intake boot carefully. If it's original there is a 2-3" crack in it allowing unmetered air into the engine. I'm surprised you're not throwing any codes with numbers like that. You tested codes with a Peake scan tool and not some random OBDII reader at a non-BMW shop, right? My Peake reader came up with a TPS code that did not appear in Torque.

Thanks for the advice, I'll check into this as soon as I have time! I don't personally own a code reader, I have no idea what the shops I've taken it to are using. Tomorrow it's going to a BMW specialist so we'll see what they say.

[reidnez]

Originally Posted by FNS_M3

Did you get the car fully warmed up before smogging? Take the car on the freeway and drive in 4th gear to get the cats nice and hot, then drive straight to the smog station and try and get it done before the cats cool down too much. It's never failed for me but YMMV.

Unfortunately I tried this before...I ran it hard for about 30 minutes on my way to the smog shop, and called ahead to make sure they would put it on the dyno and run it right away (they did). I didn't even shut it down when I got there. No dice, still failed badly. I think this trick might work if I were on the edge, but the hydrocarbons are stratospheric...too much for the cat to handle (whether it's intact or not.)

[reidnez]

Originally Posted by englishtom1596q

maybe if you had a code for o2 sensor and drove it for awhile running rich you killed your cats. and now you've fixed the o2 sensor so your not getting codes but the cats aren't doing they're job. and our cars would no way pass smog without cats, from my understanding our cars are not that efficient. however on the s54 i have heard of people passing smog with no cats due to good tuning.

Seems like a possibility, but again I still suspect a problem upstream in the fuel system; that unburned fuel (especially in such high quantities) should not be making it to the cats in the first place.