6.4 Hemi rough idle

[JALOPYJUNK]

I was curious if you have a rough idle at times. Sometimes it idles real smooth and other times it's a slight shake. Other times it's like someone pulled a plug wire off.

 

[Rockcrawlindude]

Negative

 

[Aaandroger]

I get a small miss / shake at idle. Normally after getting off the highway and coming to a stop at a light. It's so minor I tend to dismiss it.

 

[Gondul]

Nope...

 

[JimKIII]

I get a small miss / shake at idle. Normally after getting off the highway and coming to a stop at a light. It's so minor I tend to dismiss it.

Could be MDS kicking in. Does the Eco light come on when this happens? Here's an explanation of the system:

What Is Hemi MDS?

We explain how Chrysler Hemi MDS cylinder deactivation works, what goes wrong, and how to fix it when it breaks.

www.motortrend.com

 

[Aaandroger]

Could be MDS kicking in. Does the Eco light come on when this happens? Here's an explanation of the system:

What Is Hemi MDS?

We explain how Chrysler Hemi MDS cylinder deactivation works, what goes wrong, and how to fix it when it breaks.

www.motortrend.com

No. I'm sure I didn't explain well enough. This is a miss / shake at idle. MDS is not active at idle. I also turn MDS "off" by setting the gear limit to 8th gear. So, even driving, it is not active.

I was just giving variables of when I notice mine--after driving on the highway for 10-15 minutes; getting off my exit; I notice it when sitting at the traffic light (idling) right off the exit. I would imagine that this indicates that it is temperature related. I.e. only felt / noticed when the engine is up to operating temps.

Thank you for throwing something out there though. Thinking out loud, I wouldn't say that the idle is rough enough to have the dealer look at it. Or, that it would indicate any cam lobe issues. It is probably software related; at least in my case.

 

[ticpfd]

Just bought a brand new 2500 with 6.4 hemi having rough vibration in cab when at idle. Wondering the same thing if it is normal or not

 

[jetrinka]

Depends on what "rough" is. A definitive miss feeling like an ignition coil unplugged (repetitive "thud thud thud") is not normal. A slight little rumble feeling, especially when in gear is absolutely normal. A V8 is not inherently as balanced as a straight 6 would be and a little bit of a vibration is totally normal. Any V8 I've had is exactly the same. I think a lot of people are paranoid of the "Hemi Tick" and then are hyper sensitive about anything having to do with the engine.

The OP however has had (i believe) 2 engines replaced though and is still fighting something horrible with his truck so I have no doubt his issue is real. Everyone else are likely not.

 

[JALOPYJUNK]

Depends on what "rough" is. A definitive miss feeling like an ignition coil unplugged (repetitive "thud thud thud") is not normal. A slight little rumble feeling, especially when in gear is absolutely normal. A V8 is not inherently as balanced as a straight 6 would be and a little bit of a vibration is totally normal. Any V8 I've had is exactly the same. I think a lot of people are paranoid of the "Hemi Tick" and then are hyper sensitive about anything having to do with the engine.

The OP however has had (i believe) 2 engines replaced though and is still fighting something horrible with his truck so I have no doubt his issue is real. Everyone else are likely not.

This feels like a miss that is not turning on a CEL. On a scale of 1 to 10 I would give it a 4 when it happens. I can also hear it in the exhaust and see a rpm change. The dealer is stumped. They have sent the computer data to STAR and everything comes back fine. This truck had the engine replaced at 4400 miles. The new engine has 1700 miles on it. I know this truck is not going to get the best fuel mileage. Today I filled it up and it took 14.9 gallons to go 129 miles. This was about 85 percent city and 15 percent highway. I'm old so I drive this truck like an old lady.

 

[OLEJOE]

I’ve got a 22’ and when first taking off in it the first trip of the day it feels like it has air in the fuel system. Not really a miss but not taking the fuel like normal. Don’t know if it’s in the fuel system, electronic throttle or programming. Just over 4k miles so far. Doesn’t do it all the time but I thought I might get a few more miles on it before I take it in. No cel or anything. Stop and start driving isn’t going to get any fuel mileage in any vehicle as heavy as these.

 

[av42083]

Depends on what "rough" is. A definitive miss feeling like an ignition coil unplugged (repetitive "thud thud thud") is not normal. A slight little rumble feeling, especially when in gear is absolutely normal. A V8 is not inherently as balanced as a straight 6 would be and a little bit of a vibration is totally normal. Any V8 I've had is exactly the same. I think a lot of people are paranoid of the "Hemi Tick" and then are hyper sensitive about anything having to do with the engine.

The OP however has had (i believe) 2 engines replaced though and is still fighting something horrible with his truck so I have no doubt his issue is real. Everyone else are likely not.

 

[av42083]

I have a 2021 ram 2500 and I have same issue. It was smooth when I first got it. Then I noticed at around 30,000 miles a slight shake in park or at stop light. I also noticed it would randomly stop here and there now it’s constantly doing it at 50,000 miles. It’s not normal mine used to run very smoothly. It’s like a very soft stutter I’m going to test the o2 sensors to see if they are failing