No. You need a code reader to completely clear the trouble code out of the PCM. You can turn off the CEL though by disconnecting the negative battery cable and holding the ignition key in the "start" position for about 20 seconds.

Jimmy

 

So I got in my truck this morning to go to work and the "Check Engine Light" turned off!! When I got home from work I did the 3 key turn thing and i got code P0304 which is cylinder 4 misfire!!

Is it possible there was just some dirty fuel that messed up the spark plug and is clear now?? and the computer cleared the check engine light??

 

No telling...seems to me you would have multiple misfires if you had bad gas, all 6 injectors get the same shot of gas from the tank. I wonder if there might have been debris on that plug that finally cleared off. Since the CEL was off when you got the misfire code, maybe that was an old code that someone else fixed the problem but they did not reset the PCM. Or maybe the plug and/or wire is intermittently losing connection or you have a bad wire, distributor cap or rotor button. Maybe try a complete tune-up with good quality plugs, wires, cap and rotor button. Then use a code reader to clear all codes out of the PCM and drive the truck for a few days, see how it runs and see if the CEL comes back on.

Jimmy

 

ya I was thinking about doin a complete tune-up. whats a good plug and spacing, wire, distributor cap to get??

 

A lot of us here use the Autolite 3923 plugs. I used to run those myself but on my last tune up I changed to NGK. Autolite plugs are made in China now and the quality is just not as good as before. Autolite still may have some plugs that are made in Mexico. I went with NGK in the stock heat range and on my truck anyway they work just as well if not a little better than Autolite. The NGK's for the 3.9 are made in Japan but that is OK with me. I bought my plugs, wires, cap and rotor button all at Napa. The cap and rotor button with the brass contacts work best, they last longer and help get a few more volts and a better spark to the plugs. Cap and rotor Napa part numbers are MO 26 and MO 28. I do not know the NGK plug part number. I use an OEM size and style wire set, the Belden Premium Plus set from Napa, around here they cost about $34.00, they are a lot better than the $20.00 cheapie sets at other parts stores, are better than OEM quality and plus they are a cool blue color. I have been using Belden plug wires for years and never had a single problem with them.

There are a lot of different opinions on tune-up parts here. A bunch of guys here swear by the 3923 plugs, and they do work very well in our engines. They are one heat range colder than stock and can help eliminate preignition pinging. No matter which plug you use be sure it is a copper core. There is no need for platinum, iridium, plutonium or kryptonite spark plugs in a 3.9. Dodge engineers actually did a study some years ago and found that the Magnum engines perform best with a plain old copper core plug.

Jimmy

 

octane of the gas

 

I'm thinking i'll get all NGK plugs, wire, cap, and button if possible. Just got to figure out the right spacing for them.

And i just use regular fuel.

 

Good. If by spacing you mean the gap for the plugs just gap them at the factory recommendation since you have a stock ignition. It should be .040". There should be a sticker on the bottom of the hood telling you the gap specs, and it's in the owner's manual too.

Jimmy

 

Thanks Jimmy.