2003 grand Am misfire

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chewy71

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Hi, I am trying to help my friends daughter with her grand am. It is a 2003 V6.

It is running rough and the code is P0300. I think that is random misfire. In addition to running rough it is making an ominous clanking noise.

First thing I did was check for spark on all cylinders with an in-line spark tester. Spark appeared to be ok. Next thing I tried was disconnecting the wires 1 at a time to isolate the clanking noise. With the number 5 wire disconnected the noise went away and the idle smoothed a bit.

I guess the question is what is making the clanking noise? Is it internal engine damage? What else should I check before giving up and having it towed to the shop?

Thanks in advance,

Mike
 
can you tell if the noise is coming from on top or from the bottom? has it been tuned up recently?
 
I don't think the car has been tuned up in a long time. I am concerned that it may be a bottom end noise. It sounds like it could be a bottom end knock since it is kind of deep sounding. I have been searching the web for info and it sounds like if the noise goes away when you take the plug wire off or ground it, it is an internal bottom end issue.
 
not sure if this will help but try seeing if the firing order is correct,by this website http://autorepair.about.com/library/firing_orders/bl-fo-1117.htm
now it could be knocking because you may have blown a spark plug/wire on one of the other cylinders..so say if you blew a plug/wire on 3 it could cause 5 to knock since it has to pull more weightand by pulling the wire on 5 you made everything even ..so if the plugs/wires are good then it most likely is a spun rod..but try what i said first..if it does not help then, to the shop it goes..
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I know you checked the spark..but have you tried to pull the connector to the injectors 1 at a time?
 
Interesting idea about the opposing wires. I will check. Also will pull the injectors one at a time and see what happens.

thanks
 
I hope it's this easy man...i hate to hear you had to rebuild..so good luck and god speed..I know! over dramatic lol keep us posted
 
OK, so I have pretty much determined it is a bottom end issue. My mechanic friend says he will take a look but I have to get the car to him. His question to me was how hard is it to remove the oil pan? The car is a 2003 3.4. Does anyone have an idea of the procedure or difficulty?
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