6.4L rough idle at start

[Knoxville_3500]

Hello , I have a 2018 Tradesman 3500 that has a small rough idle at start , I was wondering if this is typical with the 6.4l hemi . After the truck warms up it seems to be fine. On the way in to work this morning I had the gas cap light come on in the truck and that's what prompted me to question if this is normal.

2018 3500
5k miles
Regular gas used.

 

[RoadRamblerNJ]

Not on my 2500 6.4 and I'm also in Knoxville so, same temps.

With 5k miles, your break-in period is broke-in. Have you dumped the original oil tet? That 0W-40 PUP is excellent quality oil.
When I start up, it goes right to high idle at about 1200 rpm if memory serves. My neighbors in the nearby apartments just love that loud, growling 392 at high idle. It idles really smoothly though. Nothing that you could call rough. Idle drops down in the first 2 or 3 minutes if I don't touch the gas pedal. I'll get exact cold rpm read about 15 minutes, gotta go food shopping. Hasn't run since yesterday.

Welcome to the forum.

 

[Knoxville_3500]

Hey Roadrambler,

Thanks for the feedback , I just dumped the oil yesterday and it still seems like it has a light miss the first 10 seconds or so after start. It did it in warm weather as well. The gas cap warning did not come on on the afternoon commute after I tightened the cap so hopefully that is not a problem. I did ask the guy at the dealer and he said that the rough start was normal but after your comment I see that it's not.

 

[bglz42]

Mine does it sometimes. I am 30k miles now, so apparently not a problem. Just a big motor clearing its lungs...

 

[RamCares]

Hey Roadrambler,

Thanks for the feedback , I just dumped the oil yesterday and it still seems like it has a light miss the first 10 seconds or so after start. It did it in warm weather as well. The gas cap warning did not come on on the afternoon commute after I tightened the cap so hopefully that is not a problem. I did ask the guy at the dealer and he said that the rough start was normal but after your comment I see that it's not.

Hi Knoxville_3500,

If you end up making a formal appointment with your dealer to take a look, please know that we would be more than happy to escalate a case on your behalf to get you connected with a case specialist for an additional layer of support while your truck is in service. Our team is just a private message away.

Mark
RamCares

 

[RoadRamblerNJ]

Hey Roadrambler,

Thanks for the feedback , I just dumped the oil yesterday and it still seems like it has a light miss the first 10 seconds or so after start. It did it in warm weather as well. The gas cap warning did not come on on the afternoon commute after I tightened the cap so hopefully that is not a problem. I did ask the guy at the dealer and he said that the rough start was normal but after your comment I see that it's not.

No. Not normal. That's their way of saying they don't know. Because you said it goes away fairly quickly, they count on you just letting it go. Like I said, your truck engine is broken in. Rough idle is either a timing issue, gas:air issue, sensor issue, fuel injector(s) issue, sticky lifter or a really great, lopey cam ;>)
Can you plug in a scan tool to see if there are any codes?

 

[Al Handy]

Mine does the same, almost sounds like the MDS is on, which I guess could be possible if the oil has not filled the lifters on the initial start up (????) It does go away after several seconds. It does it only on the first start up, rest of the day is OK. I just hope this does not lead to lifter problems further down the road.

 

[derag2]

Mine has it also. These engines seem to vary alot on how they act.

 

[ripping r]

Mine does it also. first start for 10s if that. but mine sits all week to.

 

[Jeff Courtney]

My 3500 has it also. I got it in April 2018. Noticed it the day after bringing it home (1st "cold" start) but goes away after warming up. I hate the MDS on these trucks. Not that thats what I think causes the rough idle. I just wanted to vent, LOL.

 

[mtofell]

My 2014 with 92K has always sounded a bit rough for the first 10 seconds or so but then smooths out perfectly. I'd say if it works itself in less than 15-20 seconds you are fine but I'm just kind of guessing. If it's under warranty I'd just wait and see if it turns into something more serious.

 

[GsRAM]

Yep, mine also guys. Dealer installed an update on mine early on, but it didn't help much. It bothers me a little.... but I just learned to lose with it like the park to reverse grind, the coolant smell I always smell, etc. I still love this truck.

 

[Chad prater]

My 2020 tradesman has the same issue. It was throwing codes but the dealer replaced injectors, plugs, cam sensor and coil packs so now just has the rough idle. The truck received a new long block @ 10,000 miles because of an engine knock. Funny thing is the original motor ran great other than the knock. When the truck goes to MDS its noisier also now. I drive a 2018 and a 2019 for work and they don't do it so definitely not normal. Chrysler care is a joke. Truck should have been bought back. Sadly, I'll be buying a Ford or Gmc when vehicles become available again. Chrysler lost me after this experience.

 

[HEMIMANN]

Gasoline quality? Running Top Tier additive gas? Faulty MAP sensor? O2 sensor. I have a 6.4 with no such issues. 43,000 miles. Top Tier gas only. 89 octane only.

 

[GsRAM]

Mine still does it occasionally to this day and has not gotten any worse. Clearly something isn't right, but no codes and runs good.

Ford and GM build decent trucks, well Ford anyway, I'm not a GM truck fan at all. They all have issues, none are perfect, but I still love my ram to this day

 

[Nickx86]

on cold starts or let my truck sit for a few days will start and idle rough for about 10 second, then goes away. I’ve also noticed when it gets to close to needing an oil change, I do mine every 5k

 

[bigdodge]

It's it rough idle or rough start? Reason I ask is mine would have an occasional rough or stutter start and occasional gas cap light. Progressed to doing it every time I filled up. Found the problem to be the vapor canister purge valve in the engine bay. Haven't had any of those issues since replaced.

 

[BLUEDERANGO]

I'll just join in,, mine does it also, just on first cold start, seems to be just a part of the program from the other posts on here. I am not losing any sleep over it.

 

[Chad prater]

It's it rough idle or rough start? Reason I ask is mine would have an occasional rough or stutter start and occasional gas cap light. Progressed to doing it every time I filled up. Found the problem to be the vapor canister purge valve in the engine bay. Haven't had any of those issues since replaced.

Rough idle after start up. The previous long block didn't do it.

 

[Chad prater]

on cold starts or let my truck sit for a few days will start and idle rough for about 10 second, then goes away. I’ve also noticed when it gets to close to needing an oil change, I do mine every 5k

This one does it during cold start or if I've let it sit for 4 or more hours.