I have a 2003 Dodge Neon SXT. It currently is misfiring randomly and has codes P0300 and P0351. I wanted to know if they're related and if replacing my Ignition Coil pack would fix the problem. I'm also going to get my fuel system cleaned.

 

yes replace that and wires/plugs while your at it

 

Okay thanks!

 

Before you sink money into the coil take out the plugs and check to see if there is oil in the tube wells. If there is then remove the valve cover, pull out the tubes and reseal them with a new gasket set and put threadlock on the tube and push back into the head. If that doesn't do the trick then the coil, plugs and wires.

 

Thank you Steve! I didn't find any oil in them or around them but I replaced the gasket set anyway just to be safe. Now I just have to wait for my ignition coil pack to come in the mail & I'll see if that does the trick.

 

UPDATE: I went to have the fuel system cleaned by Sears, since the coil pack didn't fix the misfiring. Sears technicians then told me they couldn't clean my fuel system since it was running really rough & misfiring (the misfiring was throwing the P0300, which causes a blinking engine light) so they ran a diagnostic and told me that it might be the PCM. I told them I had looked for PCMs before so I kinda knew that so they didn't charge me the ridiculous $80. My neighbor told me that the garage in my town would clean the fuel system even with the flashing light. I left my car at the garage and about ten minutes after I got home, they called me and told me they weren't cleaning the fuel system because it most likely wouldn't solve the issue. So I told him that sears referenced the PCM issue so he is now going to check and see if they're is any loose connections ANYWHERE that would cause this. I don't know what else to do besides get another PCM which for 2003's are IMPOSSIBLE to locate anyone who sells pre-programmed PCMs and going to a dealer would just roadkill on my wallet. Any other suggestions?

 

I don't get why they told you it could be the PCM. The transmission wouldn't cause it to run rough unless it wouldn't downshift or upshift when it should (automatics).

Many Neons, if not all have a rough idle issue. There are various fixes for it but the root cause is a programing error for the throttle plate position while its idling. I've heard people can go to Dodge and have them reflash the ECU so the computer correctly opens the throttle plate to allow it to idle quietly. I haven't done this to my Neon but I did dissemble the throttle body and clean it and the plate off. I also ran some fuel injector cleaner even though I don't think additives really work but since then the car idles just fine. A very slight idle issue if i have the air turned on. I guess because of the extra power needed because of the AC compressor. It used to shake the entire car before that.

Since you replaced the coil pack did you do the plugs and wires? I know you said you would. Also, a new air filter can't hurt. Have you checked your mounts? The upper and lower Torque struts are notorious for failing. Those are $35 from Advance, order online and save 20-40% with codes. Worst case scenario is you did all this and it doesn't fix the issue, but at least it will all be taken care of now.

 

Both mechanics have confirmed its the ECM/PCM because I had bought a remanned ECM before the misfiring started and just found out the dealer I got it from flashed it TOTALLY for the wrong model and ultimately thats what's causing the misfiring so the dealer is trying again free of charge! So I'll have it by Tuesday so i hope this works

 

Got the new ECM but now my car wont hold an idle?! whats going on Im at my wits end!