Hi All
I've have a 06 Magnum 2.7 with 69,000 miles that will miss sometimes at a low rpm but will smooth out at a higher rpm. It only does this every now and again. It sets a code and turns on the check engine light. PO300 multiple cylinder misfire code. I changed the plugs and they didn't look bad. Looked into the cylinders with a fiber optic camera. Head ports and valves looked super clean. I've been told from the dealer and other ppl that it is carbon built up on the valves doing this. I've ran top end engine cleaner thru it three times. It still does it.
What I don't understand is if it is carbon build up. Why is it not showing that cylinder code as a misfire. PO301,PO302,PO303 ect. I don't understand how more than one could misfire at the same time due to carbon.
If anyone has a fix or answer for this it would give me some (at-a-boys) with my wife!! I've been working on this since we bought it with 45,000 miles on it.
Thanks Passnbyu

 

Hi all, I'm sure more than one owner is having the same problem I'm having. I'm leaning towards the TPS (throttle positioning sensor). It seams to stop when I hit the gas. The check engine light is on most of the time now. Always the same code PO300 multiple cylinder misfire.
Any help will be appreciated!! Passnbyu

 

Hi All, Still having the same problem. The check engine light comes on and always the same code PO300 multiple cylinder misfire. Does anyone know if Dodge put out a TSB on this problem? They say its carbon build up. Then why is it not a individual cyclinder. They cant happen to all build up at the same time. Thanks Passnbyu

 

Hi All, Just renewing my thead. I'm Still having the same problem. The check engine light comes on and always the same code PO300 multiple cylinder misfire. Does anyone know if Dodge put out a TSB on this problem? They say its carbon build up. Then why is it not a individual cyclinder. They cant happen to all build up at the same time.

We have just over 100,000 on the car now. It still does the same thing. I started using seafoam in the gas tank and cleaning the throttle body with seafoam when ever I change the oil. About every 3500 miles. (Pain in the butt) It hasn't gone off in awhile but I know if I don't clean it every oil change it will set the check engine light off. We even use high octane fuel but that doesn't seam to help. Any one having the same problem?
Thanks Passnbyu

 

Hi there,

I have the exact same problem with my 2006 magnum 3.5 V6. My car will start to idle and shake quite a bit when I'm stopped or at low RPM and will do just fine at higher RPM.

I also have the engine light flashing everytime it does it. I will try cleaning the valve and see what it does.

 

I would check fuel pressure first, since you are getting random Mis-fire. maybe your fuel pump(s) is on it's way out. but unfortunately, the Magnums require special adapters for fuel pressure gauge to work.

 

I had the same issue on my wife's car too, check your coils, I had to change one of them, also take the air hose that connects to your throttle body off so you can see the throttle body function, I had to replace mine because while the hose was off the throttle body wasn't closing all the way while the car was sitting At idle, after I replaced the throttle body everything was fine

 

Have you found a solution for the p0300 code

 

After five years? I wouldn't expect an answer.