Multiple random misfire

Ridgerunnr · May 27, 2015

04 Dodge Ram 2500 5.7 hemi my check engine light is on and computer says random multiple misfire code is thrown so I changed the plugs, wires and coil packs which were all still stock so they needed changed but didn't fix the problem. Does anyone have any ideas of what could be wrong? I don't wanna throw money at it and still have issues

JPT · May 27, 2015

Ridgerunnr said:
04 Dodge Ram 2500 5.7 hemi my check engine light is on and computer says random multiple misfire code is thrown so I changed the plugs, wires and coil packs which were all still stock so they needed changed but didn't fix the problem. Does anyone have any ideas of what could be wrong? I don't wanna throw money at it and still have issues

When tracking down misfires, I do the following:

1. Plugs
2. Wires/coils (check the harness as well)
3. Compression Test
4. Fuel Injectors

I tracked down a misfire on a jeep for years. It was on one cylinder, and it passed all tests. Turns out the problem was a hardened inner o-ring on that injector. I pulled the injector out, and the o-ring was missing. I looked inside, and it was stuck in the block. I took a pick and pulled it out, it was hardened and brittle. I put the o-ring from the new injector on the old injector, and the problem was gone.

Not saying this is your problem, but just wanted to show how the smallest thing can affect these modern engines.

In my case it was cylinder 3 (303 code), it just came and went. When it is multiple cylinders, I typically lean towards damaged harness, or head gasket (easy to tell from a compression/leak down test).

Ridgerunnr · May 27, 2015

Also when I first start it up it hesitates and sometimes backfires at the beginning of the pedal but when I get into the throttle it runs fine also after a few miles symptoms go away (seems to only happen when first started even if I turn it off and start it back up w engine warm)

Joe.G · May 29, 2015

I had the same issue, I Did a full tune up and cleaned the TB with no change, I then Changed all 4 O2 sensors, and I also changed all of my Valve springs at the same time ( I heard horror stories about the 03/04 springs ) and everything seems to be good to go now.

Ridgerunnr · May 29, 2015

Joe.G said:
I had the same issue, I Did a full tune up and cleaned the TB with no change, I then Changed all 4 O2 sensors, and I also changed all of my Valve springs at the same time ( I heard horror stories about the 03/04 springs ) and everything seems to be good to go now.

I've changed every one of those except valve springs and the code connect on my code reader said valve springs was to number 1 solution.

Joe.G · May 29, 2015

I did o2 and springs at the same time, so I can not tell which cleared it up, I did not find any broken springs but figured id change them just to be safe, the truck has 100,000 Miles on it

Ridgerunnr · May 30, 2015

It's inly doing the hesitation on start up once I pull out of my driveway and get to the stop sign 1 mile away it's gone. It reminds of being flooded out I've sunk about 2k into since I bought it couple months ago (wheel bearings, rotors, calipers, brakes,plugs,wires,coil packs,4 O2 sensors) just don't wanna change anymore stuff that don't need it yet but sounds like we have same issue. Were the valve springs a pain?

Joe.G · May 30, 2015

The were not to bad, but depending on the springs you get you may not be able to use the standard type install tool. I replaced mine with factory 5.7 springs and they come with a collar around the spring which caused the issue with the standard tool.

carrmann · Jun 4, 2017

was this issue solved?

MarshRam · Jun 4, 2017

The dreaded P0300....Had the same issue on my 2007 dodge. Did all kinds of tests and replaced a few parts until finally found out there was a piece chipped off my fuel injection idle control valve. That also lead to 3 cracked injectors. Replaced and problem was finally fixed. Check your idle control valve and inspect it, it is very easy to pull off and is one of the many culprits attributed to random misfire.

carrmann · Jun 4, 2017

MarshRam said:
The dreaded P0300....Had the same issue on my 2007 dodge. Did all kinds of tests and replaced a few parts until finally found out there was a piece chipped off my fuel injection idle control valve. That also lead to 3 cracked injectors. Replaced and problem was finally fixed. Check your idle control valve and inspect it, it is very easy to pull off and is one of the many culprits attributed to random misfire.

OK i will indeed check it. is that the idle air control valve?

MarshRam · Jun 4, 2017

Yes, it is attached to your throttle body. I had a chip off the first inner lip where that first inner o ring is. Here is a pic of it.

Also forgot to mention, they can get old and stick as well. You can move the the black plastic valve piece and it should snap back in to position.

https://www.1aauto.com/idle-air-con...N1DhN4nhvOJjrGza5dgg6zB6bEzG5IcQZ_xoCGfXw_wcB

carrmann · Jun 4, 2017

MarshRam said:
Yes, it is attached to your throttle body. I had a chip off the first inner lip where that first inner o ring is. Here is a pic of it.

Also forgot to mention, they can get old and stick as well. You can move the the black plastic valve piece and it should snap back in to position.

https://www.1aauto.com/idle-air-con...N1DhN4nhvOJjrGza5dgg6zB6bEzG5IcQZ_xoCGfXw_wcB

ah, did some searching. the hemi doesnt have one. time for more searching.

MarshRam · Jun 4, 2017

Well that sucks, could be injectors, but could be so many things. MY 07 didnt like platinum plugs, had to go back to copper, very picky truck. Random misfire is the biggest headache I ever dealt with and ultimately ended up costing me $1500. Ran like a champ after all those new parts though. I regretted not checking the injectors in the end, decided to take it to a mechanic and got charged $600 in labor for diagnosis and replacement. Best I can say is test and inspect everything you can, like fuel and exhaust pressure. It's really hard to pinpoint on a forum since so many things can be the cause.

MarshRam · Jun 4, 2017

Oh yeah, also check compression, vacuum leaks, MAF, etc. You can easily find a list to go through on the internet. Good luck dude!

carrmann · Jun 4, 2017

thanks again. code changed. now it doesnt have p0300. has p0335 and p0340.

MarshRam · Jun 5, 2017

Camshaft, crankshaft sensors?? Doubtful its both and possibly could be neither. When I had the misfire issue, I would throw a few other random codes every once in awhile. Thats why I threw quite a few parts at it before finally figuring it out. Like I said, I would test and inspect what you can, the true issue could just be throwing those sensors off. Sorry your going through this, it is very frustrating.

JPT · Jun 5, 2017

carrmann said:
thanks again. code changed. now it doesnt have p0300. has p0335 and p0340.

Both of these went bad at once for me. They aren't really hard to do, but at least one of them is a pain to remove (the one on the side of the engine as it is pressed in).

Multiple random misfire

Junior Member

Senior Member

Junior Member

Senior Member

Junior Member

Senior Member

Junior Member

Senior Member

Junior Member

Senior Member

Junior Member

Senior Member

Junior Member

Senior Member

Senior Member

Junior Member

Senior Member

Senior Member

Similar threads

Forum statistics

Share this page