1994 Chevy Camaro exhaust system mal-function

Tiny
FIGUE04
  • MEMBER
  • 1994 CHEVROLET CAMARO
  • 6 CYL
  • 2WD
  • MANUAL
  • 125,054 MILES
Can, anyone please assit? Having problems with my vehicle's exhaust system. Change the cat, o2 sensors and the EGR valve on it to improve and lower the emmisions emmitted from the car. Within 3 days the cat went out and a new one was installed, again within 3 days the new cat went out. Car runs great and gives 20mpg, only thing bad on it is that there is smell of exhaust within the cabin and rattleing sound from the under the car and last; when car is coming to a stop a sound similar to a backfire. Please help. Thanks.
Tuesday, February 12th, 2008 AT 2:35 PM

13 Replies

Tiny
2CARPRO JACK
  • MECHANIC
  • 11,533 POSTS
If it has big exhaust leaks (smell in the car) then the mixture will read off to the o2 sensors and it could change the mixture to the point that it hurts the cats. How do you know the cats are going out?
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Tuesday, February 12th, 2008 AT 3:33 PM
Tiny
FIGUE04
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I have been told that the cats are burning up. Due to the rattling sound coming from that area. Would this be ture? Or am I being told this in mistake?
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Tuesday, February 12th, 2008 AT 4:35 PM
Tiny
2CARPRO JACK
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Could be, but I personally have never seen one go to pieces in 3 days. Might be pieces of the old one in the muffler. Are you using aftermarket cats?
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Tuesday, February 12th, 2008 AT 5:37 PM
Tiny
FIGUE04
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I think they are after market cats. I will have them verify that there is no debris from the earlier cat within the pipes. Can this be preventing the vehicle from passing smog?
I have change sparks, spark plugs cables, o2 sensors, had the egr valve cleaned and PVC valve exchanged and still did not pass.
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Tuesday, February 12th, 2008 AT 5:43 PM
Tiny
2CARPRO JACK
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Is the check engine light on? What part of the test is it failing?
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Wednesday, February 13th, 2008 AT 7:08 AM
Tiny
FIGUE04
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According to the person doing the test, the emissions tests. Bad egr, o2, and cat.
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Wednesday, February 13th, 2008 AT 9:29 AM
Tiny
2CARPRO JACK
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I need better info. He obviously is having a hard time here. If you cant give me the info let me know
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Wednesday, February 13th, 2008 AT 9:48 AM
Tiny
FIGUE04
  • MEMBER
  • 8 POSTS
Engine light does not come on or stay on. According to test location its is burning fuel to rich. Cat is good according to a most recent muffler shop just visited (yesterday).
Actions taken prior to smog test: Oil nad filter change, spark plugs and wires exhcnage for new ones, o2 sensors exhange, catalytic revised (rattling sound coming from within), heat sheilds secure.
Result: Technitian did not want to continue with the test due that vehicle, displaying various problems; o2 sensors, bad cat, egr, pvc valve all faulty.
I have since went back to the shop where all the exhanges had been made and requested that they be revised, anticipating a faulty piece of equipment. It all checked out and all were good.
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Thursday, February 14th, 2008 AT 3:26 PM
Tiny
2CARPRO JACK
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What are all the readings for the failed emission test?
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Thursday, February 14th, 2008 AT 3:44 PM
Tiny
FIGUE04
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  • 8 POSTS
NO (PPM)
15 mph: 692(max) 150(ave) 1566(meas)
25 mph: 711(max) 136(ave) 1621(meas)

This is the only portion of the tet that it has failed. I did take the vehicle to another Smopg shop (more trustworthy) recommended by local Chevy dealer. Hopefully this will give you a better undeerstanding of what needs top be done to my vehicle. Thanks
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Monday, February 18th, 2008 AT 12:14 PM
Tiny
2CARPRO JACK
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Nox is EGR function. Good source vacuum at the EGR solenoid? If valve is pulled on manually with vacuum pump does the engine stumble to the point of almost stalling? If not the passages are plugged. If all ok, then I would go for the EGR control solenoid
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Monday, February 18th, 2008 AT 6:28 PM
Tiny
FIGUE04
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EGR valve is electric, cannot perform a vacuum test on it. Or can a test on the vacuum be performed? EGR control solenoid? Where is it located on a 94 camaro?
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Friday, February 22nd, 2008 AT 3:54 PM
Tiny
2CARPRO JACK
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Electric doesnt have one. Might be a problem with the PCM
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Friday, February 22nd, 2008 AT 5:10 PM

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