08 Charger R/T Replaced spark plugs now have a P0300 and really rough idle

Last week I replaced my spark plugs which looked to be copper plugs with some new champion double platinum spark plugs. It ran epic until yesterday when it wouldn't start up after turning it off, I was finally able to start it while pumping the gas pedal but it would not stay running. After pushing it home I ran it long enough to get a code, p2308-ignition coil "c" secondary circuit. I cleared the code, moved the coils around and started it back up and it ran better and had a different code P0300-random multiple misfire. I went and bought two new coils and and installed them, I tried them in multiple different combinations and still get the multiple random misfire P0300 ! But after adding two new coils it ran even better than before. It seems to idle without me using the gas pedal for a while but then eventually dies. Does anyone have any idea what this could be ? I would try to re-install the old plugs but the wife threw them out already !

 

I wonder if it would be worth it to go buy some champion copper plugs and try swapping out ?? It seems too coincidental to have this happen right after changing to a different plug, the very next week to be exact.

 

Update, I just went out and had it idling while I sprayed mass airflow sensor cleaner (all I had) around the intake area and when I got close to the pipe from the EGR where it goes into the intake and it killed the engine instantly. Also would like to add that when I have the key in the run position but not running, the EGR vale is kind of whining... not sure if that is relevant or not.

 

Yes it is a hemi.

 

I would agree with you about the EGR. the fluid sprayed should not enter the system from the outside. it is an exhaust gas recirculating valve, ( poor seal leak )

other potential causes: low fuel pressure, Vacuum leak, cam crank sensors, low compression,

Cats or O2 sensors. all have precise test procedures you can do.

by changing the plugs ( Platinum run hotter ) your engine highlighted the actual cause that was there. You must have changed the plugs for a reason Miss fire, poor performance maybe ?

Plugs should have a nice TAN color on the porcelain, black color running RICH fauling, burnt running too Lean hot,

Just a couple suggestions - always place a dab of DIALECTIC grease inside the spark plug boot and any wire connectors - this prevents corrosion and keeps moisture out while making it easier to disconnect and reconnect next time.

2 ) always use ANTI SIEZE paste on all bolts and screws. prevents them from freezing to aluminum, and different metal composites like spark plug threads.

 

Bad new fellas, I was pulling the spark plugs and found a cylinder with two smashed plugs ! grabbed a bore scope camera and looked into that cylinder and sure enough I have metal chunks down there and one hell of a beat up cylinder head. when I took off the intake plenum I had pieces falling out of it too including some piston ring pieces. I just cant believe this happened, someone told me I jumped a link in my timing chain.... I had no idea that could happen. Well pulling the motor now and getting ready to be broke for a while since the full rebuild is said to cost $4000. I appreciate you guys getting back with all the suggestions so soon, looks like I'm it it for the long haul.

 

Sorry to hear this, sounds like a real nightmare.