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Loud noise / Backfiring Problem

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Old Jul 19, 2010 | 01:26 PM
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Default Loud noise / Backfiring Problem - UPDATE

Hi people,
About two months or so ago, I was driving my 92 vert and all was fine. After about an hour or so ride home, I stopped to pick up my daughter. The car was off for about 15 minutes. When I got back in and started it up, it was much louder than usual. Not a good loud either. Info to note, the car has muffler elims on it. I limped it home and took a look underneath. I could not find any exhaust leak issues evident. With the car idleing in the garage it sounded fine, so I took it for a ride. It was obnoxiously loud and backfired every time I took my foot off the gas. Seems like a back pressure issue?!?!

Any ideas? I'm dieing without my car for the whole season so far. Help!!

Thanks,
-Rick

Last edited by cicch95; Jul 28, 2010 at 06:34 PM.
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Old Jul 19, 2010 | 02:42 PM
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Look for exhaust leaks around the exhaust manifolds. You may need to buy a mechanic's stethoscope.
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Old Jul 20, 2010 | 08:43 AM
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Originally Posted by Paul Ruggeri
Look for exhaust leaks around the exhaust manifolds. You may need to buy a mechanic's stethoscope.
Are you thinking the top end of the manifolds, near the motor?
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Old Jul 20, 2010 | 08:49 AM
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Cracked header maybe?
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Old Jul 20, 2010 | 10:15 AM
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Maybe a bad spark plug or wire? That can cause a backfire and because the pulses are uneven, make the exhaust appear louder.
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Old Jul 20, 2010 | 10:35 AM
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Originally Posted by cicch95
Are you thinking the top end of the manifolds, near the motor?
Could be there or the flange or even a cracked manifold or one of the air injection tubes.
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Old Jul 20, 2010 | 12:10 PM
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Hmmmmmmm...all good thoughts. I will have to get back out to the garage. Thanks.

I'll let you know what I find out.
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Old Jul 20, 2010 | 12:29 PM
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Always a good idea to check for stored trouble codes first.
To me it sounds like a valve isn't opening. You might want to pull the valve covers and take a look for loose stuff.

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Old Jul 20, 2010 | 03:03 PM
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On another Forum, a guy just spent a LONG TIME, and investigating all sorts of things, trying to track down a back-firing problem. Turned out to be a bad plug wire (#5) that crumbled when he tried removing it.

Replacing it cured his issue.

Jake,
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Old Jul 20, 2010 | 03:11 PM
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Originally Posted by engle1147
Always a good idea to check for stored trouble codes first.
To me it sounds like a valve isn't opening. You might want to pull the valve covers and take a look for loose stuff.

Zoiks....now you're scarin me!
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Old Jul 20, 2010 | 03:13 PM
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Right now, I'm down with the flu or something......I must take a look when I get better. I hope it's something simple....and not one of the more serious suggestions. Thanks for all the replies.
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Old Jul 20, 2010 | 03:47 PM
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Originally Posted by cicch95
Zoiks....now you're scarin me!
My bad - could be something simpler....feel better then troubleshoot the car.

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Old Jul 28, 2010 | 06:37 PM
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OK, so I am finally feelign better so I went out to the garage and took a look. I could not find any problems with the exhaust. The wires are all on tight and feel soft, no dry rot. I do not hear any noise from under the valve covers, so at this point I chose to leave them on!

I jumped the codes and got a 43 and a 64. So, these tell me that I had a problem with either the knock sensor and/or theo2 sensor. Right? Could this cause my problem? (see above)

Thanks,
-Rick
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Old Jul 29, 2010 | 01:55 PM
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Ttt
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