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Discussion Starter #1
exhaust/catalytic question clogged cat???

i have a 2007 impala lt 3.9l, im pretty sure its not getting good flow through the exhaust, is the catalytic converter the only thing that can cause bad flow over time? or can other things also affect the flow? i get a firework/sulfur smell coming from the tailpipe, smells like some one just blew up a firecracker or something, now i know people say its prolly ur cat.. but i also heard that a bad o2 senser or a bad MAF could be making it smell bad cuz the gasoline mix wouldnt be right, i just dont wanna ruin the engine, and i dont just wanna go ahead and replace the cat if its not the problem and its gonna continue to smell, today on the way home from work it did seem kinda sluggish like it took more pedal to get moving like somethings being restricted. i got home and put my hand on the tailpipe and it didnt seem as if it was really blowing that hard, also the right muffler seemed to be putting out a little more exhaust, anyways, if anyone has any idea id be glad to hear from you
 

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Back in Black
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sounds like a bad cat, how many miles on car?
Take it down and have it scaned at advance or another auto parts store they maybe able tosee a code that could point to your problem
 

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Back in Black
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I would have it scaned for codes. If it does not seem to have power when you take off and you have to feather the gas to keep the car from bogging down, along with them smell I would bet cat. a bad Maf could cause the same trouble but they usually do not have a sulfur smell.
 

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Discussion Starter #5
ok. Ill prolly scan it in a couple days when i have a day off. The only thing is that theres no check engine light on so im not really sure if any codes will pop
 

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Definitely the cat, but you may want to look into WHY it clogged, so it doesn't ruin the new one as well.
 

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Discussion Starter #7
ok. Gonna be looking into it more wed and thurs. I dont wanna bring it in though will cost way to much. I just hope i can find the problem
 

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Discussion Starter #8
well i changed the spark plugs today, and wow, that was a job! pretty sure i was the first one to change them, they were rusted and looked pretty worn. now i just gotta look into the converter, anyone know where to get one for fairly cheap, the cheapest i can find is $270 for a direct fit, otherwise i could get one for like 90 bucks but then i would have to do some welding and mods which im not sure im down with, any suggestions? and also how bad is it to drive around withought perfect flow going through the exhaust?
 

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Cat

I agree with the rest that it sounds like classic cat problems. Like they said though, as it plugs it should lose power when accellerating. Also after late 96 we went to OBDII so unless they changed it again, you should have 2 O2 senors. One before and after that read and compare to each other. I would think that should throw a code. Maybe it's just not bad enough yet. It use to be cheap to purchase aftermarket Cat's until OBDII started. They really went up and got harder to get.

jeff
 

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Discussion Starter #10
is there anything else that can cause the sulfur smell besides a bad cat?? thanks everyone for your responses!
 

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Somebody hiding in the back seat lighting matches? Other than that, not really, no.
 

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Discussion Starter #12
lol ill make sure i check my back seat next time i go for a drive! I scanned it for codes today and it didnt throw any. For some reason the catalyst and evap system monitors were not completed. It said "diagnostic system reports that one or more readiness monitors are not complete. Drive cycles need to be run to complete all supported monitors" so i took it for a 20 minute drive and scanned it again and those 2 still didnt complete. Any idea? Other then that the scan was good
 

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If the computer was recently reset, or the battery disconnected, it will reset the monitors. Those two take forever to run, I wouldn't worry too much about it for now.
 

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Discussion Starter #14
ok makes sense now i disconected the battery to remove the ignition coil. thanks everyone for all the replys. much appreciated!
 
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