Dodge 2015 ram 1500 5.7 Hemi shudder

After the weekend hunting my BILs truck started to shudder/shake when getting on the throttle. We didn't notice anything putting around the mtn all day, but coming out of the canyon it started. Had the code read and it shows misfire on cyl8, he changed the coil pack on cyl8 and all 16 plugs since it has 155K but issues persists. There was a slight tick from cyl8 area, and he said the new plugs on 8 are wet with fuel smell, sounds like wiring/ecu to me since no spark is getting to cyl8? He thinks it may be a flat cam or valve issue and that it may need a rebuild.
I initially thought it felt like a transmission issue until we had the code read.

Any thoughts one what it may be, anyone heard of this issue?
Or good shop recommends for a rebuild.

I know there were some years that the Hemi's had lifter problems caused by the shutting off of cylinders when the engine is not under load to create better fuel economy. This would be where I would start looking.

The lifter issue is pretty well documented. Definitely a good place to start.

- DAA

Flat cam is a good bet. The variable displacement lifters are known to fail and cause a flat cam lobe. The good thing is as long as the heads are good they are normally easy to rebuild. The blocks wear really well. I've had a 200000 mile block in my garage that you could still see cross hatching

We had a number of Hemis the last place I worked and flat cams were definitely an issue.

Thanks everyone, seems to line up with what he was finding. Guess we will see if it is something we can get done ourselves and avoid labor costs.

xjtony said:

Flat cam is a good bet. The variable displacement lifters are known to fail and cause a flat cam lobe. The good thing is as long as the heads are good they are normally easy to rebuild. The blocks wear really well. I've had a 200000 mile block in my garage that you could still see cross hatching

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What I was going to say. This problem is what swayed me away from a new gasser ram. 6.4s have same issue

TRD270 said:

What I was going to say. This problem is what swayed me away from a new gasser ram. 6.4s have same issue

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🤫 I’m not listening

you should delete the hydralic lifters while youre in there

Well he got lucky, turns out it was the wires to the coil pack, they had hairline cracks and that was enough to cause it to misfire. Cheaper and less time consuming than cam/lifters or rebuild.