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View Full Version : instaled the cat. on the car now it idles rough ????



mexicangio
02-21-2015, 01:26 AM
hello everyone!


so i just bought a 2001 Audi a4 1.8t quattro and it had a 034 motorsport downpipe, the guy threw in the catalytic converter so it would pass smog. i just finished swapping out the straight downpipe for the cat and the struggles when i tuned it on i had to step on it to get it to idel right. then is sounds like it wants to turn off. i drove it for a little bit and it seemed to be ok but just idle dosn't feel quite right feels like it will die any moment when idling. the car also has a UNITRONIC stage 2 flash . idk if that would matter ?? im really want it to pass smog then put the downpipe back in and everything back to normal. any ideas maybe i just pinched one of the vacuum lines i did have to remove the air box and move a bunch of lines. [wrench][headbang][confused][confused]


http://i30.photobucket.com/albums/c329/mexicangio/IMG_20150220_171233.jpg[/URL][/IMG]


http://i30.photobucket.com/albums/c329/mexicangio/down%20pipe2.jpg[/URL]

Dcass08
02-21-2015, 04:57 AM
Could be a vacuum line or maybe a connector. Also try unhooking the battery for a few minutes to reset things. you don't get a cel do you?

gmx
02-21-2015, 06:17 AM
did you replace the gasket?

mexicangio
02-21-2015, 06:41 AM
I unplugged the battery and no CEL on so I'm going to go and try to get it smogged today, and will check the lines just in case I missed something thanks

mexicangio
02-21-2015, 06:42 AM
did you replace the gasket?
No I used the same ones but the bottom of the cat only has 2 out of 3 bolts because one was broken off

viceprp
02-21-2015, 06:53 AM
L-l-leak

adam044
02-21-2015, 09:13 AM
Bad O2 sensor?

mexicangio
02-21-2015, 11:59 AM
L-l-leak
Yeah that's what I'm hoping it is I went to auto zone to buy the extra bolt needed

mexicangio
02-21-2015, 11:59 AM
Bad O2 sensor?
I hope not I haven't had any CEl since the swap

mexicangio
02-21-2015, 01:32 PM
http://i30.photobucket.com/albums/c329/mexicangio/Mobile%20Uploads/IMG_20150221_130357.jpg (http://s30.photobucket.com/user/mexicangio/media/Mobile%20Uploads/IMG_20150221_130357.jpg.html)

Took the car to get smoged this code cane up anyidea what it means I'm guessing its from the leak where its missing flange bolts for the exhaust, thoughts?

Davdraco1
02-21-2015, 01:47 PM
Yea, you need that bolt. You will always have a leak unless you seal it properly.

mexicangio
02-21-2015, 02:19 PM
Yea, you need that bolt. You will always have a leak unless you seal it properly. OK thanks for your help and input ! Excited to be part of the Audi community ! Successful first post

gmx
02-22-2015, 06:18 AM
The description of the bolt as per OP sounds like it post O2 sensor even though he says he removed the cat ???
That shouldn't cause his drivability issues. It sounds like there is a leak pre primary o2 and the same gasket was re-used.
That or you have unmetered air leak entering most likely via TIP.

viceprp
02-22-2015, 02:38 PM
He also reused gaskets. I never ran into any exhaust gasket that held up well enough to reuse.

mexicangio
02-22-2015, 05:31 PM
Yeah I just ordered new gaskets and bolts. I wanted it to pass smog and it did so mission accomplished but the tech said it was the top o2 sensor needed replaced, the car also has a k&n air filter so I'm thinking of cleaning the MAF since it on of those reusable filters

mexicangio
02-22-2015, 05:35 PM
I'm also going to reinstall the 034 Motorsport downpipe but I've seen a o2 spacer to avoid CEL does anyone have experience using one of these ? Is it worth it

http://store.034motorsport.com/o2-sensor-spacer-for-bosch-style-sensors.html

coolgraymemo
02-22-2015, 05:56 PM
I'm also going to reinstall the 034 Motorsport downpipe but I've seen a o2 spacer to avoid CEL does anyone have experience using one of these ? Is it worth it

http://store.034motorsport.com/o2-sensor-spacer-for-bosch-style-sensors.html

Just buy one of the Help! ones from Autozone. They are about five dollars. I'm running two on my car and no codes.

Google for the part #