Cadilliac Loud Backfire Noise

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  #1  
Old 05-12-06, 04:04 PM
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Cadilliac Loud Backfire Noise

My 1989 Cadilliac Devillie backfires very loud & bust an new muffler.Does anyone know what could cause the car to backfire & what repairs,parts that are needed to stop the backfiring.
Could it be the Cadilliac Converter needs to be replace or removed? Could bad spark plugs or/& wires cause the car to backfire? Repair shops said it was the timing then the map senor but those things are done & it still backfires.
Thanks,in advance.
 
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Old 05-12-06, 06:06 PM
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I'd say you either have unburned gas getting into your exhaust, or the exhaust valve during the explosion is not closed, due to way off timing or burned valve.

Gas flooding the exhaust could be from poor ignition; weak spark from a plug or other ignition issues. Have you pulled your plugs to have a look at them? You may even have something as severe as a missing an electrode for all you might know.

You could have a vacuum advance (if an 89 would still have one of these things) that maybe is not working and is staying severely retarded when it should be advanced.

Timing belt/chain may have jumped one cog.

Do you still have a catalytic converter on the car. Those babies get so hot (that could probably make raw or partialy burned gas explode) that they can start a grassfire under your car if you park over tall grass. (I learned this from my own experience. ) Has THAT exploded, or a regular muffler?
 
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Old 05-12-06, 07:31 PM
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Cadilliac Backfires--DaVeBoy

DaVeBoy,
First I would like to say many thanks for taking the time to respond to my questions. You're so helpful.I don't know anything about repairing a car at all.

When I started the car tonight I smell gas fues inside.It start jerking then it backfires loud.I just notice one of the spark plug wires is burn.Was told to start the car & look under the hood to see if there sparks of fire near the wire or plugs & if it was it needed wire or/& plugs,But I didn't see any sparkes at all.
The orginal muffler had an hole in it when it backfired, so I had a new one install & the new muffler didn't last 3 days & it blew it wide open when it backfire twice.I think its was the muffler & not the cadilliac converted because the car sound like a truck after the car backfired.I
**Vacum Advance?
** Missing Electrode?
Catalytic Converter is still on the car should I have it removed?Sorry I don't have any idea on what it is or what it does. I'm
 
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Old 05-12-06, 08:33 PM
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Ifr you really don't know anything about cars, it is real hard to try to guide you without epistle or novel-esque posts, and...well, I've overstayed my welcome at my friends computer...it's getting late... and I need to run, and maybe someone else can step in here.
 
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Old 05-12-06, 09:37 PM
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Originally Posted by NET247
DaVeBoy,
First I would like to say many thanks for taking the time to respond to my questions. You're so helpful.I don't know anything about repairing a car at all.

When I started the car tonight I smell gas fues inside.It start jerking then it backfires loud.I just notice one of the spark plug wires is burn.Was told to start the car & look under the hood to see if there sparks of fire near the wire or plugs & if it was it needed wire or/& plugs,But I didn't see any sparkes at all.
The orginal muffler had an hole in it when it backfired, so I had a new one install & the new muffler didn't last 3 days & it blew it wide open when it backfire twice.I think its was the muffler & not the cadilliac converted because the car sound like a truck after the car backfired.I
**Vacum Advance?
** Missing Electrode?
Catalytic Converter is still on the car should I have it removed?Sorry I don't have any idea on what it is or what it does. I'm
Go back to square 1 , make sure timing is right, replace any bad plug wires, check condition of air filter and/or proper placement of air cleaner unit, do you have any trouble codes stored ? ( is check engine light on ? ), it will most likely be related to the timing , it shuouldn't backfire in the first place regardless of muffler with holes or not , timing belt comes to mind too, cat converter basically prevents pollutants from getting out to the environment, be careful it runs really hot ! , they do quit after sometime too , double check timing first.
 
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Old 05-12-06, 10:14 PM
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LouBazooka

Thanks, for the advice,]
The timing was checked & I was told that it was not the timing because if it was the car would not start or could be driven aty all.That's was what I was told by a shop.The muffler didn't have any holes in it at all until the backfiring started,then the pressure from the loud backfire cause the muffler to bust open.I was told to start the car & look under the hood to see if any fire was near the wires or spark plugs but it was no fire or sparks when it started .So was told if it was not then the spark plus & wires didn't need replacing.I can start the car without any problems but the backfire noise & the jerking is scary.Sometimes it will not backfire for 2 days then it will start back .Sorry for the long email.You're too kind to offer help.I wonder could an burn spark plug wire cause it to backfire? I also had the map sensoe replace & the fuel pump also tried higher gas hoping that help but it didn't .Thanks again
Muffler shop say they will not replace my muffler because the backfiring cause it to bust so I'm out of almost $200 for the muffler.
Thanks,very much
 
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Old 05-13-06, 04:40 PM
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Originally Posted by NET247
Thanks, for the advice,].... & the jerking is scary.Sometimes it will not backfire for 2 days then it will start back .
Two good additional clues, guys.
 
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