Engine Troubles-rough idle

[Mattyhooks]

Hello, I am currently seeking some guidance or insight my truck.

Problem- Rough idle at cold and warm start, in neutral, drive, pretty much all the time. RPMs typically start between 700-1500, then after a few seconds down to 500. Currently, shaking occurs at all RPMs. Sometimes it holds 700 or 1000 or 1500, but will shake throughout. MPG typically range from 16-20 and haven't changed much. I may have messed up by running 87 Octane Top Tier until 36K miles. The rough idle issue began right around 30K and it didn't seem that bad. At 36K, I had cylinder #5 misfire. I changed the sparkplug and rotated around coil packs and still no fix. I got it to the dealership, they recommended a fuel system flush/clean, which they performed, and switching to 89 Octane. Since that visit, I have ran nothing but 93 Octane Top Tier. Next day, Idle rpms are around 1500 and smooth. Driving normal, then CEL pops on, and cylinder #4 misfire and P0441 evap leak. Due to service availability, dealership looked at it about a week later, but the codes went away before they looked at it. Obviously they couldn't determine the problem, but did an engine combustion CPU update. Seem fine for a few days idling between 700 and 1500 RPM no shaking. Shaking returns, low RPM and P0441 code returns. At this point, no noticeable MPG or power loss. Return to the dealership, they find a cracked hose and replace. Few days after code has not returned, but idle seems iffy. A few weeks go by and now idle is constantly at 500 RPM and shakes. Sometimes shaking is more violent than others.

Could this issue be the result of running 87 Octane? The misfires indicate a fuel injector problem. It appears every time the dealership looks at it, the rough idle problem is fixed for a short time period, then returns. It makes me wonder what they are they doing /not doing. What are your thoughts? Iwill gladly take any advice.

Thanks in advance!

 

[NetNine]

I assume that your dealer's shop already looked, but double check that there are no obstructions in the air filter box, and that the air filter is intact/clean Take the air intake box cover off, lift the air filter, look at the filter make sure it's OK. Now look into the bottom of the box, make sure that there are no foreign objects, etc. You may be surprised what finds its way in there. This past winter, I had a squirrel make a home in the bottom under the air filter. Half the box was stuffed with nuts, shells, dry leaves, chewed up shop towels. I noticed the idle was getting rough on a cold start, and when I went to check on the air filter, that's what I found.

 

[Oldphart]

Can't help with the issue, but you said the dealership stated the "codes just went away". That can't happen unless they are deliberately deleted. I'd be looking for another dealer pronto.

 

[Snekpete]

I had a similar problem with my 2015 Mustang GT, but without the P0441 evap leak. On the GT it turned out to be a broken running valve actuator in the intake manifold. On these high tech motors the engineers put rails or butterfly valves in the intake manifold to restrict airflow at low rpm. The valves pull open at WOT but if one stays open you get a rough idle and midrange. Check the valve actuator on the same side as the number 4 cylinder. The P0441 would suggest a vacuum leak to the actuator or in the actuator.

Also try searching Youtube for similar problems, that's how I diagnosed the GT. A dealer will never get that kind of fix.

 

[Dusty1948]

I had similar symptoms last year for a period, then got a P-441. Service tech. found the code was being set by the Fuel Tank Pressure Sensor/Recirculation Tube Assembly (52029939AC). After replacement, fine ever since.

Best regards,
Dusty
2019 Ram 1500 Billet Silver Laramie Quad Cab 2WD, 5.7 Hemi, 8HP75, 3.21 axle, 33 gallon fuel tank, factory dual exhaust, 18” wheels. Build date: 03 June 2018. Now at: 053719 miles.

 

[Mario CPA]

Hello, I am currently seeking some guidance or insight my truck.

Problem- Rough idle at cold and warm start, in neutral, drive, pretty much all the time. RPMs typically start between 700-1500, then after a few seconds down to 500. Currently, shaking occurs at all RPMs. Sometimes it holds 700 or 1000 or 1500, but will shake throughout. MPG typically range from 16-20 and haven't changed much. I may have messed up by running 87 Octane Top Tier until 36K miles. The rough idle issue began right around 30K and it didn't seem that bad. At 36K, I had cylinder #5 misfire. I changed the sparkplug and rotated around coil packs and still no fix. I got it to the dealership, they recommended a fuel system flush/clean, which they performed, and switching to 89 Octane. Since that visit, I have ran nothing but 93 Octane Top Tier. Next day, Idle rpms are around 1500 and smooth. Driving normal, then CEL pops on, and cylinder #4 misfire and P0441 evap leak. Due to service availability, dealership looked at it about a week later, but the codes went away before they looked at it. Obviously they couldn't determine the problem, but did an engine combustion CPU update. Seem fine for a few days idling between 700 and 1500 RPM no shaking. Shaking returns, low RPM and P0441 code returns. At this point, no noticeable MPG or power loss. Return to the dealership, they find a cracked hose and replace. Few days after code has not returned, but idle seems iffy. A few weeks go by and now idle is constantly at 500 RPM and shakes. Sometimes shaking is more violent than others.

Could this issue be the result of running 87 Octane? The misfires indicate a fuel injector problem. It appears every time the dealership looks at it, the rough idle problem is fixed for a short time period, then returns. It makes me wonder what they are they doing /not doing. What are your thoughts? Iwill gladly take any advice.

Thanks in advance!

I've had the same problem but my truck has been doing that idle shake since new, I tested a few other RAM 1500's and they all had the idle shake. I used 93 octane for a few tanks and it didn't make a difference. I'm ready to bring it back to dealership. It seems like it shakes at idle only, if I bring the rpm's to a 1000 it smooths out.

 

[Drewster]

How long do you let your engine idle? If you're one of those who lets the truck idle to warm up on a daily basis - stop doing that. There's actually a warning in the manual about how it creates carbon buildup, etc.

Definitely check out the tank hose that Dusty mentioned, but if it slowly just comes back I would wonder if it needs an Italian Tune-up...

 

[Tyglesias]

Hello, I am currently seeking some guidance or insight my truck.

Problem- Rough idle at cold and warm start, in neutral, drive, pretty much all the time. RPMs typically start between 700-1500, then after a few seconds down to 500. Currently, shaking occurs at all RPMs. Sometimes it holds 700 or 1000 or 1500, but will shake throughout. MPG typically range from 16-20 and haven't changed much. I may have messed up by running 87 Octane Top Tier until 36K miles. The rough idle issue began right around 30K and it didn't seem that bad. At 36K, I had cylinder #5 misfire. I changed the sparkplug and rotated around coil packs and still no fix. I got it to the dealership, they recommended a fuel system flush/clean, which they performed, and switching to 89 Octane. Since that visit, I have ran nothing but 93 Octane Top Tier. Next day, Idle rpms are around 1500 and smooth. Driving normal, then CEL pops on, and cylinder #4 misfire and P0441 evap leak. Due to service availability, dealership looked at it about a week later, but the codes went away before they looked at it. Obviously they couldn't determine the problem, but did an engine combustion CPU update. Seem fine for a few days idling between 700 and 1500 RPM no shaking. Shaking returns, low RPM and P0441 code returns. At this point, no noticeable MPG or power loss. Return to the dealership, they find a cracked hose and replace. Few days after code has not returned, but idle seems iffy. A few weeks go by and now idle is constantly at 500 RPM and shakes. Sometimes shaking is more violent than others.

Could this issue be the result of running 87 Octane? The misfires indicate a fuel injector problem. It appears every time the dealership looks at it, the rough idle problem is fixed for a short time period, then returns. It makes me wonder what they are they doing /not doing. What are your thoughts? Iwill gladly take any advice.

Thanks in advance!

Same problem on my 2020 1500 limited. It's happened since I've had the truck, but only in cold weather and on cold start. Dealer has tried just about everything (been in 8 times or so) and now have an "in flight recorder" hooked up to it. Working on trying a buyback for this expensive turd of a truck.

 

[OhioBigHorn]

I have this issue as well. I run 89 octane. Does it in park and at red lights almost feels like a strong wind rocking the truck. Sometimes it doesn't do it at all. Sounds like it is normal. Only 25000 miles on truck. Any updates on this?

 

[Mattyhooks]

I have this issue as well. I run 89 octane. Does it in park and at red lights almost feels like a strong wind rocking the truck. Sometimes it doesn't do it at all. Sounds like it is normal. Only 25000 miles on truck. Any updates on this?

After going back and forth with the dealership, I gave up and just live with it. They told me the likely cause is an Intermittent Misfire, but could never get it to reproduce enough to save a code or log. They also said that's what Hemi's do. I gave them my truck for 4 weeks and no result. I was also told my truck wasn't the only one this was happening to. What else was weird, was when I got Mopar involved (so I could get a loner) the dealership was able to find the problem, but never fix it. The dealership offered me $40K for the truck in this condition also... I am a fool for not taking it, since I paid $36K

I'm sitting right around 80K miles now, strictly 89 or 91 Octane and it comes and goes. Its not as frequent as before, which leaves me to believe my issue was from 87 Octane.