2005 Buick Century random misfire

2005 BUICK CENTURY
65,000 MILES • 6 CYL • FWD • AUTOMATIC
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JUSTIN U
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I have a 2005 Bucik Century that is very hard to start and is running extremely rough. I can the codes and found code po300 for random misfire. I have checked the plugs and wires and dont see anything out of the ordinary. I am looking for a little help with the diagnosing of this. Any Ideas?
Jan 3, 2009 at 12:02 PM
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BRIAN 1
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remove each sparkplug wire from each coil pack and see if the towers on the coilpacks are rusty or burnt,very common problem. post back with what you find and will advise from there.
Jan 3, 2009 at 1:28 PM
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JUSTIN U
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I have already had the wires off the coil pack and didnt see any rust or corrosion of any kind
Jan 3, 2009 at 1:31 PM
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BRIAN 1
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you will need a scan tool to find out which cylinder or cylinders are missfiring,this could be fuel related or spark related or mechanical.it's very hard to say what it is with out some sort of testing.try and find out if it's spark or fuel.post back with any other questions.
Jan 3, 2009 at 1:41 PM
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JUSTIN U
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i have been told that the egr valve could cause this. is that possible'
Jan 3, 2009 at 1:45 PM
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BRIAN 1
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it could,but this missfires all the time if it was the egr there would be an egr code and if it was the egr when the car was cold it would run fine until it got warm and the egr started to operate then it would run rough.
Jan 3, 2009 at 1:51 PM
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JUSTIN U
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ya thats true. Im not really sure what is goin on with this thing it just started missing all of the sudden and will not start without excessive cranking and pumping the pedal which to me seems crazy. but i may have to get my hand on a better scanner
Jan 3, 2009 at 1:56 PM
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BRIAN 1
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if you have to pump the pedal to start thats a fuel problem.check the fuel pressure with a guage and post back.
Jan 3, 2009 at 3:05 PM
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JUSTIN U
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i got outside just in time to see my dad trying to get it running with starting fluid. (scared the crap out of me) but it still wouldnt start
Jan 3, 2009 at 3:47 PM
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BRIAN 1
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what do you mean,did it start with starting fluid or it just wont start? I need you to check fuel pressure,we need to start somewhere.
Jan 3, 2009 at 6:46 PM
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JUSTIN U
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i have realized that it will start and run on its own when it is cold but once the engine heats up it starts to miss and then will die. They checked the fuel pressure today and said that it was normal
Jan 4, 2009 at 6:52 PM
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BRIAN 1
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then we need to check spark,take some soapy water in a spray bottle and spray the wires while its running and see if there are any sparks,to check for a bad wire also pull some plugs and see if any are cracked or have carbon tracking.it's very hard to help when we dont know what cylinder or cylinders are missfiring,this could still be fuel or spark problem.could be a bad injector,bad wire,bad coil pack,bad plug,etc.post back with what you find.
Jan 5, 2009 at 9:59 AM