04 ram 1500 5.7 hemi
174000 miles

New parts ive just recently installed:
Radiator. Water pump & thermost. Ps pump & cooler. Coolant control temp.

Recently got out of the army and needed a vehicle so i decided to buy my dads dodge as he is currently deployed overseas and wants a new truck once he returns home. It sat about 1.5 to 2 months between him leaving and me buying it. Had a more mechanical savvy friend look it over for me and recommended some parts to be replaced, which i listed above. Then it started misfiring with a p0300 code. Recommended the coolant temp sensor be changed so i did and the misfire went away but 24 hours later the misfire returned. After research and learning it could be a list of many many things causing the misfire I just decided to do the spark plugs. Found one was cracked so i replaced it. Cleaned the others and regapped them. I know, i should have replaced all of them but i have not had income for a bit now and cant replace them til i start work. Anyways i put the plugs back in and everything, started it up and drove around and no more misfire. Drove around an hour or so later that evening no issues. Engine sounded great amd smooth. Went to go onto town this morning and after 6-8 minutes of driving the misfire came back, along with the same p0300 code.

So does anyone know why the misfire and code go away after those repairs but return the next day? Also have codes for 02 sensors. P0152 and p0038 i believe.

 

Figure out what the P0152 is all about, and see if that doesn't also address the misfires.

 

Another thing thay just clicked today..i realized that when ive replaced the parts the 2-3 different times ive obviously unplugged the battery and when i get done with everything and plug the battery back in and then start it and let it run and get up to temp theres no misfire. So then i always drive it after and usually for about 30 minutes each time. The misfire stays away for maybe 12-15 hours then it comes back. So maybe something to do with the ECU? Or sensors maybe? I cant seem to find anything online about it. Also thanks i will start that p0152 in the morning then

 

Or crappy O2 sensors giving false readings to the PCM, so it leans you out to the point of lean-burn misfires......

 

okay thanks
will work on that hopefully that is the issue

 

Easy test is to unplug the front O2 sensors, and see if the problem goes away.

 

I’m still pretty new to working on vehicles and what not but from what I seen today there are two cats so should I unplug both of the sensors before each cat?

 

Yup. Exactly.

 

Okay so I just unplug them from the electrical side and leave the other side that’s in the cats plugged in? And should I have the truck running while I unplug them to see if anything changes or just unplug while it’s off then start it up after?

 

No, unplug when the truck is cold. (trust me on this.....) Be sure and put the connectors out of harms way. Zip tie them somewhere if you have to. Otherwise, they seem to be attracted to really hot things, like exhaust manifolds.