Cat back exhaust causes inefficient Cat????

Kostaman · 02-16-2005, 05:29 PM

Anyways,

After getting rear ended on marine drive a couple months ago, my check engine light has been turning on and off almost randomly. After taking it to Jonny at advance and getting it diagnosed, i found out that my cat is damaged. He tells me to take it to Don Docksteader and mention to them that I got into an accident that could have possibly damaged my cat.

So after Subaru checks it out... they also conclude that my cat is running inefficiently, but they tell me that it's because my exhaust it too big. Now I'm confused... i'm no car buff, but i know that air leaves the exhaust pipes one way..... out the back of the car no? If that truly is that case, then how can a larger exhaust cause my cat to run inefficiently.

Perhaps it's another case of stiff the man with the aftermarket modifications? Or I ****ed up somewhere?? Any help would be appreciated.

.....or.... does anybody who's running catless right now want to sell me their cat possibly for cheap?

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madmanslegacy · 02-16-2005, 05:34 PM

Go catless?My kids should have black lungs like the rest of them!

Kostaman · 02-16-2005, 05:39 PM

Perhaps... I bought my car late 2002, when's the first time i need to go to aircare? Will I pass with a faulty cat? I probably won't pass if i'm missing a cat im guessing.

bwco · 02-16-2005, 05:49 PM

kosta, your inefficient cat code might be caused by the rear O2 sensor.
If CEL flickers frequently, i guess it must be that sensor cause I'd the same thing with my bmw before (bmw with custom 3" cat back exhaust). Replacing a rear O2 sensor would be an easy job.
Buy the O2 sensor and do it yourself or I'll help you in your garage.
By the way, I kinda suspect that your exhaust leaks somewhere in the front too.

anyone guessing otherwise?

DON'T GO TO ADVANCE AUTO ! **Labor cost gonna kill you

Kostaman · 02-16-2005, 05:53 PM

yeah, i'm gonna take it back to parks today to see why the exhaust rattles too... u said before that maybe the axleback part isn't bolted flush with the middle pipe? i dunno.. thanks billy

Marty Gagnon · 02-16-2005, 07:23 PM

Quote:

Originally Posted by madmanslegacy

Go catless?My kids should have black lungs like the rest of them!

you might as well sell your car, move to Kyoto and buy a Horse.

bwco · 02-16-2005, 07:35 PM

Quote:

Originally Posted by Kostaman

yeah, i'm gonna take it back to parks today to see why the exhaust rattles too... u said before that maybe the axleback part isn't bolted flush with the middle pipe? i dunno.. thanks billy

no i didn't say that.
I heard the hissing sound from your exhaust before you got it fixed.
My guess was a leak anywhere from the turbo. Could be the downpipe or midpipe. Also, you remember that your car got pushed in the front too? Just a little impact may cause the exhaust mainfold to leak. So, get the entire exhaust mainfold> uppipe> uppipe bung> downpipe> downpipe sensor bung> center pipe> midpipe> midpipe sensor bung> axle back fully inspected (well, just by looking or feeling of the gaps is good enough if your really have a leak)

Don't quote me on the leaking part, cause I'm no expert in cars. All i can do is oil change.

-S- · 02-16-2005, 08:15 PM

Quote:

Originally Posted by Marty Gagnon

you might as well sell your car, move to Kyoto and buy a Horse.

Ah yes, because Kyoto has the cleanest air of all world cities? And why stop at horses? Use those fat legs! Don't you know horses pollute?

RDS · 02-16-2005, 08:48 PM

If you change the exhaust flow (larger exhaust and free flowing muff.) it may set a cat eff. code because the cats are designed to run on the stock flow.
If they can not keep up with the exhaust , the Rear O2 sensor will see the out put of the cat is not correct. Try the stock exhaust and see if the light still comes on. Good Luck

madmanslegacy · 02-16-2005, 09:06 PM

Quote:

Originally Posted by Marty Gagnon

you might as well sell your car, move to Kyoto and buy a Horse.

Good idea, im guessing since you live in TO, you've already considered this.
Oyeaah, the topic: Take bwco, and RDS's info.

02-16-2005, 05:29 PM	#1
Kostaman Scooby Newbie Member#: 25544 Join Date: Oct 2002 Location: Richmond Vehicle: 2003 WRX sedan Black	Cat back exhaust causes inefficient Cat???? Anyways, After getting rear ended on marine drive a couple months ago, my check engine light has been turning on and off almost randomly. After taking it to Jonny at advance and getting it diagnosed, i found out that my cat is damaged. He tells me to take it to Don Docksteader and mention to them that I got into an accident that could have possibly damaged my cat. So after Subaru checks it out... they also conclude that my cat is running inefficiently, but they tell me that it's because my exhaust it too big. Now I'm confused... i'm no car buff, but i know that air leaves the exhaust pipes one way..... out the back of the car no? If that truly is that case, then how can a larger exhaust cause my cat to run inefficiently. Perhaps it's another case of stiff the man with the aftermarket modifications? Or I ***ed up somewhere?? Any help would be appreciated. .....or.... does anybody who's running catless right now want to sell me their cat possibly for cheap? Registered users of the site do not see these ads. Last edited by Kostaman; 02-16-2005 at 05:34 PM.

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02-16-2005, 05:34 PM	#2
madmanslegacy Scooby Specialist Member#: 25911 Join Date: Oct 2002 Chapter/Region: VIC Location: Vancouver Vehicle: 89 R32 GTS-T Black	Go catless?My kids should have black lungs like the rest of them!

02-16-2005, 05:39 PM	#3
Kostaman Scooby Newbie Member#: 25544 Join Date: Oct 2002 Location: Richmond Vehicle: 2003 WRX sedan Black	Perhaps... I bought my car late 2002, when's the first time i need to go to aircare? Will I pass with a faulty cat? I probably won't pass if i'm missing a cat im guessing.

02-16-2005, 05:49 PM	#4
bwco Scooby Specialist Member#: 44137 Join Date: Sep 2003 Chapter/Region: VIC Location: Vancouver, BC	kosta, your inefficient cat code might be caused by the rear O2 sensor. If CEL flickers frequently, i guess it must be that sensor cause I'd the same thing with my bmw before (bmw with custom 3" cat back exhaust). Replacing a rear O2 sensor would be an easy job. Buy the O2 sensor and do it yourself or I'll help you in your garage. By the way, I kinda suspect that your exhaust leaks somewhere in the front too. anyone guessing otherwise? DON'T GO TO ADVANCE AUTO ! **Labor cost gonna kill you

02-16-2005, 05:53 PM	#5
Kostaman Scooby Newbie Member#: 25544 Join Date: Oct 2002 Location: Richmond Vehicle: 2003 WRX sedan Black	yeah, i'm gonna take it back to parks today to see why the exhaust rattles too... u said before that maybe the axleback part isn't bolted flush with the middle pipe? i dunno.. thanks billy

02-16-2005, 08:48 PM	#9
RDS Scooby Newbie Member#: 81404 Join Date: Feb 2005	If you change the exhaust flow (larger exhaust and free flowing muff.) it may set a cat eff. code because the cats are designed to run on the stock flow. If they can not keep up with the exhaust , the Rear O2 sensor will see the out put of the cat is not correct. Try the stock exhaust and see if the light still comes on. Good Luck