Misfire

P0303 DODGE - Cylinder Misfire Fault Detected...Possible causes; Faulty spark plug 3, Clogged or faulty fuel injector 3, Faulty ignition coil 3, Fuel injector 3 harness is open or shorted, Fuel injector 3 circuit poor electrical connection, Ignition coil 3 harness is open or shorted, Ignition coil 3 circuit poor electrical connection, Insufficient cylinder 3 compression, Incorrect fuel pressure, Intake air leak...The P0303 code means that the cylinder 3 is misfiring or is randomly misfiring. Start by checking for intake leaks an if no leaks are found the next step is to replace the spark plugs on cylinder 3. If the problem persist more tests needs to be done to diagnose problem.

I was having this same issue after replacing all the coils with new cheap ones. I initially replace them because I never had them replaced in 2003 RAM 1500 4.8 (18 years).Note; the engine light was on for the previous 3 years, and since the truck was running fine I learned to leave with it on. With the new coils the misfire issue returned and the engine light came back on. A computer test revealed that it was #3, which I immediately replaced. Soon after the replacement, the misfire started again, but this time it was #7 with the engine light on again. I then replaced #7 with little success. BASED ON HOW THE PROBLEM FINALLY WENT AWAY I BELIEVE THAT IT WAS A VOLTAGE PRONLEM AND NOT THE COILS. I removed the battery and in the process I noticed the connectors were corroded. I got the battery tested at a local auto parts store and was told that there were no indicators that it could be defective, but being that it had over 5 years powering the engine I was told that it would not be a bad idea to replace it with a new one. I put a new battery, new battery connectors and new batteries for the door remote, and "brrrm, brrrm" back to normal. One more note; before I installed the new battery I held the negative and positive battery connectors against each other for 15 seconds (no battery in the truck) to reset the computer. So far the engine light turned off and the miss-fire issue the truck was having has gone away. I wiil keep my fingers crossed, but so far (over 50 miles) the truck is running smooth and feeling like new. I will update if anything changes within the next 1000 miles. The computer never showed a voltage or amperage issue, but I should have replaced the original (cheap) battery connectors a long time ago. Maybe that is all it was :)