Check engine light

SilverRam11 · Jan 4, 2017

New member here, but I have a question about my check engine light that comes on and off. I have been getting code P0308 for number 8 cylinder misfire. It comes and goes, and whenever I have the mechanic look at it it's gone and the diagnostics come up normal. It has come and gone frequently and sometimes gone for a couple weeks. I'm not capable of switching coil packs and injectors around myself to see if the misfire moves, and I'm not ready to pay a mechanic to do all that yet. Any ideas? Thinking of running some sea foam through it and seeing if that helps. Thanks.

Bigdaddycodes · Jan 4, 2017

Im going to have to say that seafoam probably wont help, it actually might make it worse as it can foul out your plugs, I would find a way to move coils around, check spark plugs, if you have access to a good scan tool you can monitor the coils on it as well.

SilverRam11 · Jan 4, 2017

I purchased the truck recently so it's new to me. It has about 70k miles on it so I'm assuming I should probably put a new set of plugs in it anyways. I don't have a scan tool and when the mechanic has used one the truck has been perfectly normal. I'm just wondering what issue would come and go and perform perfectly normal for the mechanic?

Bigdaddycodes · Jan 4, 2017

Id definitely start with a set of plugs then if you dont know they were done recently, only run oem copper plugs in these trucks. is the mechanic you are going to one you trust or is it just some guy

MADDOG · Jan 4, 2017

the coming and going indicate to me a bad connection at the coil pack or possibly a broken plug wire or boot/connector.

It's time for plugs and wires. You can isolate the problem, as you know, but there's no benefit to changing just one coil pack, plug or wire. You'll end up chasing P030X codes until all parts are replaced.

The upside of isolating the faulty component on cylinder 8 is replacing one item is cheaper than replacing 3 times 8 parts.

Bigdaddycodes · Jan 4, 2017

time for plugs, he wont have wires. and I am going to have to disagree on replacing all the coils at one time, with only 70 000miles they should still be fine, if the one coil is at fault then just the one is needing to be changed, as for plugs though, definitely replace them all at once. and then there are no wires to replace. it could be just a bad connection but i dont see it being that simple, that should be the first thing your mechanic should have checked.

SilverRam11 · Jan 4, 2017

Thanks for the replies. I trust my mechanic very much, he has been working on all of my vehicles and my fathers vehicles for longer than I have been alive. I will start with a set of plugs and see where that goes, do I need to do all 16 or can I get away with the top 8 first?

Hootbro · Jan 4, 2017

Not being capable of doing this or that and not willing to pay a mechanic really boxes you in here.

Some reasonable suggestions already made but keep in the back of your mind it still is shotgunning parts hoping to get lucky.

SilverRam11 · Jan 4, 2017

Hootbro said:
Not being capable of doing this or that and not willing to pay a mechanic really boxes you in here.

Some reasonable suggestions already made but keep in the back of your mind it still is shotgunning parts hoping to get lucky.

I understand and I am willing to pay a mechanic. I just don't want to pay a mechanic by the hour to fiddle with my truck in the hopes that a code may or may not appear again. If the issue weren't so sporadic then paying a mechanic might make more sense to me. I have already paid for diagnostics that came up with nothing because the issue didn't show up then. The code has shown up before and gone away faster than I could get it to the shop. When I get the plugs done maybe I can ask my mechanic to swap coils and then it's just a wait and see game.

Bigdaddycodes · Jan 4, 2017

I didnt realize it was a 4.7, I just assumed hemi, that is my bad, so there are wires to replace, but the chances of them being worn out are pretty slim, as for plugs though, I would recommend just doing all 16, especially trying to fix a misfire issue

Rado · Jan 4, 2017

MY 2 cents. More then likely it is the coil. My reason is on my Service truck every now and then It would skip, code was random mis fire, no cylinder info. did that for a few months before it finally said cyl # Our mechanic change coil and she ws good to go. Since your code was for # 8 I would either install a new coil or swap coil to another plug. Please up date what you find Thanks

RamCares · Jan 5, 2017

SilverRam11 said:
New member here, but I have a question about my check engine light that comes on and off. I have been getting code P0308 for number 8 cylinder misfire. It comes and goes, and whenever I have the mechanic look at it it's gone and the diagnostics come up normal. It has come and gone frequently and sometimes gone for a couple weeks. I'm not capable of switching coil packs and injectors around myself to see if the misfire moves, and I'm not ready to pay a mechanic to do all that yet. Any ideas? Thinking of running some sea foam through it and seeing if that helps. Thanks.

Hi SilverRam11,

Sorry to hear about this! If you decide to visit your local dealership I'd be happy to follow up with them for you if needed. Just PM our page with your VIN and let me know.

Andrea
Ram Social Care Specialist

SilverRam11 · Jan 6, 2017

Check engine light has been off again all week. Anyone want to start a wager on how long until it comes on again? (joking) I'll get the plugs done and have the mechanic switch a couple coils while they are off sometime soon, but I'll report back any changes or fixes.

averageguy · Jan 6, 2017

Bigdaddycodes said:
Im going to have to say that seafoam probably wont help, it actually might make it worse as it can foul out your plugs, I would find a way to move coils around, check spark plugs, if you have access to a good scan tool you can monitor the coils on it as well.

I am curious how seafoam fouls plugs? I have put it in boats, motorcycles, trucks, chainsaws, weed eaters, generators and anything else with a motor for the last 10 years. Out of frustration this fall I had 50% seafoam 50% gas in my riding mower because it was running rough "I only use it for 1 month in spring and 1 month in the fall so it sits a lot" and it cleared out by the end of my leaf clean up and ran great. I also use ethanol treatment since I had a carb eaten up on a leaf blower. Not trying to argue, just wondering about your experience with fouled plugs. Hijacking over.

SilverRam11 · Jan 6, 2017

averageguy said:
I am curious how seafoam fouls plugs? I have put it in boats, motorcycles, trucks, chainsaws, weed eaters, generators and anything else with a motor for the last 10 years. Out of frustration this fall I had 50% seafoam 50% gas in my riding mower because it was running rough "I only use it for 1 month in spring and 1 month in the fall so it sits a lot" and it cleared out by the end of my leaf clean up and ran great. I also use ethanol treatment since I had a carb eaten up on a leaf blower. Not trying to argue, just wondering about your experience with fouled plugs. Hijacking over.

I am also curious why it would foul the plugs. I will most likely use it anyways as I intend to replace the plugs.

PCT · Jan 6, 2017

SilverRam11 said:
New member here, but I have a question about my check engine light that comes on and off. I have been getting code P0308 for number 8 cylinder misfire. It comes and goes, and whenever I have the mechanic look at it it's gone and the diagnostics come up normal. It has come and gone frequently and sometimes gone for a couple weeks. I'm not capable of switching coil packs and injectors around myself to see if the misfire moves, and I'm not ready to pay a mechanic to do all that yet. Any ideas? Thinking of running some sea foam through it and seeing if that helps. Thanks.

I had this issue on my 04, 4.7, for years, I would have an intermediate miss, would either get p0300, or p0301, until it missed hard, pulled the number one plug out, all the porcelain was disintegrated.. but coils are easy to switch, if you can pop your hood you can do them.
Best thing to do, move your coil pack to cly 7, move the 7 to 8, and move your spark plug 6 and swap the plug from 6 to 8, or just put a new on 8.

If it follows it's a spark issue, if it doesn't then it's something else.

Sent from my SAMSUNG-SM-T817A using Tapatalk

PCT · Jan 6, 2017

averageguy said:
I am curious how seafoam fouls plugs? I have put it in boats, motorcycles, trucks, chainsaws, weed eaters, generators and anything else with a motor for the last 10 years. Out of frustration this fall I had 50% seafoam 50% gas in my riding mower because it was running rough "I only use it for 1 month in spring and 1 month in the fall so it sits a lot" and it cleared out by the end of my leaf clean up and ran great. I also use ethanol treatment since I had a carb eaten up on a leaf blower. Not trying to argue, just wondering about your experience with fouled plugs. Hijacking over.

Old timers who think they know everything will say it will clean plugs. From what I understand, when you put the seafoam in, it's going to dislodge all the carbon, and any oil that may have crusted to the piston head (assuming rings are old and slightly seap) and as you drive it all that **** gets on the plug, and can't clean it's self and will loose efficiency or just stop working. That's how I understand it. Chances are you wont damage them but cant be good for them. Especially due to the fact the op is having misfire issues, don't want to throw in another reason why it's misfiring.

Burla · Jan 6, 2017

Oil fouls plugs, sea foam is a solvent, I seriously doubt it will foul plugs by itself. But the net is full of vehicles needing new plugs after a sea foam treatment, just like PCT said. Anyhow, back to the OP, Hemi's need plugs 50% sooner then any other vehicle, start there. Keep track of all 16 plugs, put them by cylinder in a paper cup labeled for each cylinder. Order only Mopar Plugs, Moes or Amazon good place to get them, do not use something else. And double check, I think it is the 14's and up that have the 100k plugs, so if your a 13 or older you have the same burden as me, change those plugs every 30k. How many miles on the truck, sorry if I missed that? Did the mechanic not pull a plug? This maybe someone can help me on, a mis fire would mean two plugs on the same cylinder didn't fire? Does a code get tossed if one of the two plugs don't fire on any given cylinder?

PCT · Jan 6, 2017

Yeah i wouldnt do champion, or autolite, they are the worse! Have your mechanic either do an entire plug job, or if you dont wanna spend the money, have them do what i did to swap and see if the cel follows the plug the pack or stays in the cylinder...

I dont think the lower plug would really cause a misfire, unless its never been done after like 200k miles... and even then it fire on exhaust stroke if im not mistaken...

Sent from my SAMSUNG-SM-G935A using Tapatalk

SilverRam11 · Jan 20, 2017

So my misfire code isn't back, but i purchased a scan tool and now I have two evap codes 0457 and one other. Starting to get annoyed with this truck. Also it spit out a C3F03 code, what's that?

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