Cylinder 5 Misfire (Please Help)

[asphaltforeman]

2021 Ram 1500 Laramie
115,000 miles. Oil change at every interval, done at dealer.
One owner, I put these 115,000 miles on it for work. It's been taken care of.

P0305 Cylinder 5 Misfire that won't go away. I replaced the spark plugs in all 8 cylinders, as I was due.
Replaced the coil pack for Cylinder 5. Still a low idle misfire. Truck runs great when above idle rpms.
Any suggestions before I put it in the shop? Injector? ECM or PCM?
This only happens after the truck warms up.

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[BowDown]

Move the cylinder 5 injector to a different cylinder and see if the problem moves

 

[2021EcoDiesel]

I'd maybe consider trying an injector cleaner too. Some of them are snake oil, but some of them do work. I'd imagine it's a fueling issue most likely a stuck/dirty injector. I drive an EcoDiesel, but I had a stubborn injector code that wouldn't go away. Eventually I ran some Hotshots Diesel Extreme and that actually turned the CEL off and improved my running conditions.

Hopefully it's not a burnt valve or something else like that, cause that would be very pricey!

 

[6of36]

2021 Ram 1500 Laramie
115,000 miles. Oil change at every interval, done at dealer.
One owner, I put these 115,000 miles on it for work. It's been taken care of.

P0305 Cylinder 5 Misfire that won't go away. I replaced the spark plugs in all 8 cylinders, as I was due.
Replaced the coil pack for Cylinder 5. Still a low idle misfire. Truck runs great when above idle rpms.
Any suggestions before I put it in the shop? Injector? ECM or PCM?
This only happens after the truck warms up.

QuoteReply
Report

Don't get insulted, but are you sure you replaced the right coil, only replacing one? I don't know your mechanical background. My son in law went for months, chasing a miss on his. Turned out he was working on the wrong cylinder. #5 is the third one on the drivers side. He looked at a drawing, and thought it was looking from the front of the truck, instead of from the drivers seat.

 

[Quint]

On my 2015, I kept getting a misfire code for cylinder #5. This started around 85k miles, not long after I started getting the Hemi tick around 65k miles. My trusted local mechanic replaced the plug and the coil/wires twice. After the second time, he dug in further and confirmed that I was developing the cam & lifter failure. I then took it to the dealer who independently came to the same conclusion. The final diagnosis was when the truck was at about 105k and out of warranty.

I hope that you don't have the same problem, but there are some similarities so I decided to share my story in case it helps with diagnosis.

 

[BowDown]

I'd check the valve spring on that cylinder before assuming its a cam lifter issue but it'd also be running rough if that was the issue. Only occurring after warm up makes me think injector and that's its likely leaking. Pull the dipstick out and smell the oil, does it smell like fuel?

 

[asphaltforeman]

Sorry, for the delay. I’ve been swamped at work. I appreciate all the help from you guys. Just to recap, I ended up changing the plugs (16) and the coil pack for #5 cylinder. As a last resort I changed the injector for #5 and the misfire has been non-existent since. Like I said, it was due for plugs anyways since I am at 115,000 miles. That was being completed regardless of the misfire. I have a spare coil pack that is apparently good and a truck without a misfire. I plan on changing all the injectors at some point, but at $60 a pop I will take my time purchasing then change all at one time. Once again, appreciate all the tips for you guys.


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[yankeefan31569]

great info, hope it works out now and
ejnoy the ride...

 

[BlkLimited22s]

How difficult was it to replace the injector? It seems the only place to get them is from the dealer. I have a cylinder #2 misfire and swapped coil/plugs to #4 but problem did not follow. Only 46k

 

[kapinallinen2]

Ordered injector and a coil pack for P0308 from "moparfactoryparts.com"
Should be here in few days. (75k on the clock)

 

[BlkLimited22s]

I have P0302 and swapped the coil and plugs from cylinder #4. Did not fix it so I am going to try an injector but otherwise I guess I will have to tow it to dealer since I have Max care. I only have 46k on mine.

 

[BlkLimited22s]

In my case replacing the injector fixed the issue. Took about 20 minutes to swap out the injector.

 

[theblet]

Great news!

 

[kapinallinen2]

Still waiting for the coil pack and the injector.
Meanwhile, ran the tank to almost empty, put in Lucas injector cleaner and about 32 gallons of 89 octane.
I have burned roughly 1/3 of a tank and no longer get check engine light or misfire code.

 

[klotz50]

How difficult was it to replace the injector? It seems the only place to get them is from the dealer. I have a cylinder #2 misfire and swapped coil/plugs to #4 but problem did not follow. Only 46k

I just got a cylinder 2 misfire as well. 2019 with 70k on it. Earliest I can get someone to look at it is 5 days from now. Any news on yours?

 

[BlkLimited22s]

I just got a cylinder 2 misfire as well. 2019 with 70k on it. Earliest I can get someone to look at it is 5 days from now. Any news on yours?

Yes, I responded above. I replaced the injector and it fixed my misfire. Was not bad at all labor wise. Pull fuel pump relay, turned over truck several times to bleed off fuel pressure, removed air box and intake tube, removed plastic hemi engine cover, taped over throttle body to prevent anything from falling in, removed fuel rail bolts. (4), removed fuel rail, replaced injector (careful with the clip), reinstalled everything and started right up. Local dealer had 32 in stock which should tell you this happens enough that they keep stock on hand.