Hello,

My 2005 Ram 1500 with the 5.7 has been having random misfires. It bucks around, flashes the check engine light, but throws no codes.

Funny thing, all I have to do is pull-over, shut the truck down, fire it back up, and then it runs fine.

I tried searches, but I keep getting results for P0300(1-8). Again, it throws no codes, and is fine after a restart.

Thank you in adavance for any ideas.

I changed the plugs 20,000 miles ago, so another 10,000 before I have to spend 3 hours changing spark plugs. I have already replaced the EGR and PCV a while ago, too. I was thinking perhaps wires or coil packs, but but I'm not sure where to begin.

It has 70,000 miles on it now.

Jason

 

Time for wires, u use factory plugs? what octane fuel do u use?

 

Look for sparks arcing off the wires at night maybe?
Also I agree with the "factory plug" question.
I was getting the P0300 and flashing CEL because I took the advice of a guy at Advance auto parts and put Bosch plugs in mine. Good luck!

 

The plugs I used were the bare-bones copper Champions. I read not to use anything but. As for octane, I run 89 when I can afford it, but most of the time I have to use 87.

I figured it was time for wires and coil-packs if I can afford it. It just seemed strange that it would go away when I restart it.

Thank you for the responses.

 

Try using 89 and doin the wires first. At 70k its about time. 89 is only a few cents more and its whats recommended for those engines. I would clean the throttle body out too

 

Sounds like a plan.
I'll grab two cans of combustion chamber cleaner from the local dealership. One for the throttle body, and one for the intake plenum as well. I laugh like a school girl when I've done this to other vehicles in the past. Nothing funnier!

 

I would still pull the plugs and visually inspect them

 

I'm finally ready to do all of this work this weekend. As you can see, I really don't drive my truck much.
It's still doing this misfire thing. Now, it's giving me the P0300 code for a random misfire. I still plan on performing all of the tasks recommended above, but I read on another forum that the upstream o2 sensors could be the culprit.
I know o2 sensors have their own codes, but could this be something to look at as well. Looking back, it does seem like it happens at the distance/time when I leave my house. Only when it's been sitting, when I first get going on the road. In fact, when I have to pull-over it's always at the same place.
I'm wondering if one of the o2 sensors isn't quite right when it switches from open to closed loop.
Either way, as soon as I shut it off and turn it back on, it's fine for the rest of the day.

 

curious to the solution, my truck is doing the same thing and the dealership is now stumped too.

 

I haven't done a thing yet. When I get paid, I'm going to change both upstream o2 sensors first.
When I get multiple misfires, it turns on the MIL light. If I leave that MIL light on, the truck acts fine.
When I use a scanner to kill the MIL, the truck will misfire again.
So, I assume one of the sensors that is bypassed in open loop mode is causing the issue. I'm going to try the upstream o2 sensors first. I noticed that my truck had a software update before I bought it. I can't read the service sticker anymore, but I think it had something to do with the o2 sensors tripping the MIL light.
I'll let you know how it goes.