Ok,
So i just installed the 2.5 w/cat xtc downpipe in my 2.2 07.
I have no where to put the pre cat 02 sensor because there is no bung.
I started the car with the first 02 sensor disconnected lightly revved it and small amounts of white smoke started coming out from under my hood.
What the **** is going on... it didnt smell like buring plastic if that helps.

Any ideas?

Could it be the PB Blaster heating up, that i used to get the rusty bolt off the stock DP?

 

because the 02 sensor is not in...then it's not reading anything...therefore your engine is compensating for that....the 02 sensor HAS TO BE INSTALLED SO YOU DON'T RUIN YOUR ENGINE...so i suggest putting your stock dp back on...take that new dp to a exhaust shop and have them weld in a bung so you can install the 02 sensor....

the 02 sensor operates at something like 600 degrees and if the engine doesn't sense any voltage to that...then it will run extremely lean...hence the smoke...since it's running lean...it's burning coolant and that's not a good thing...you may have already ruined the engine...and that will get costly...put that stock dp back on ASAP before you really do some damage...

 

don't listen to the post above, he's not even close.

it's smoking because of all the oils on the new pipe, and it's 100% normal. the cobalts change from year to year, and it sounds like you got one of the different cobalts that has the funny 02 locations. you can either have a bung welded in, or return the part and go back to stock. only 2 things you can do.

 

on some balts, the sensor is on the DP, on most it's on the manifold. i'm guessing that you have a 2.2 with the air injection, so, it's a different manifold, you have to take the pipe to an exhaust shop and have another bung installed.

 

some have 3 02 sensors, 2 on the dp, and one on the manifold. some have 2 sensors, 1 on the manifold, and one on the dp. some have 2 sensors, both on the downpipe. i've had to tell people that i couldn't help them put their parts on because of this, since i don't have the equipment to put in a bung. it makes it pretty aggravating.

 

My o2 sensor is in my Downpipe. I had a o2 bung tig welded into the downpipe and i have no problems.

 

it's really not that bad to do, it's on my list of how-tos in the near future.