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new problem help

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Old Aug 28, 2009 | 01:01 PM
  #1  
1999mustang2000's Avatar
1999mustang2000
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Default new problem help

changed the plugs and thermostat..now when i rev the car let the rpms come down a little then rev again it pops real loud in the exhaust
Old Aug 28, 2009 | 03:29 PM
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Sounds like its backfiring, unburnt fuel in the exhaust is igniting...
Old Aug 28, 2009 | 04:13 PM
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backfiring thru the intake or exhaust? Are the plugs tight? Did it blow a plug out? Anything is possible
Old Aug 28, 2009 | 04:15 PM
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headers could have a loose bolt too
Old Aug 28, 2009 | 04:36 PM
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plugs are tight but i did have a bad o ring when i started the car and fuel squirted out a little so im not sure if maybe some got down in the plugs or if maybe some of the coolant got in them from where i changed the thermostat..


and backfiring through the exhaust
Old Aug 29, 2009 | 12:29 PM
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ok got the backfiring stopped but now it misses like crazy
Old Aug 29, 2009 | 12:31 PM
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was everything good before u changed the plugs?
Old Aug 29, 2009 | 12:39 PM
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yea it had a little miss before
Old Aug 29, 2009 | 12:44 PM
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u probably got a bad coil then. if the check engine light is on take it to advance. (they will scan it for no charge) any code between a p0300 and p0308 is cylinder misfire. (ie p0304 is cylinder # 4 misfire. then u will know which coil or coils to look at. also what type of plugs did u use?
Old Aug 29, 2009 | 01:11 PM
  #10  
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autolite double platnum



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