2017 5.7 VERY Rough Idle…But only for a minute

[mwaters97]

A fully charged 12V vehicle battery should read 12.6 volts or higher. IMO your battery is on the way out.

I agree that your throttle body should be cleaned and intake retorqued (I have retorqued mine a couple of times) but I am leaning toward a battery issue seeing what yours is reading.

Both the throttle body and intake have specific procedures that should be followed. Threads on those can be found by searching the forum.

Okay, thank you good info.

Just an update: I’ve put about 250 miles on just since the day of the issue and posting. Multiple occasions of parked idle. And everything has been totally normal

The battery being the culprit is interesting to me, as it really hadn’t even crossed my mind. Like some of the other members mentioned, my mind was focused on the big 3: fuel, air and spark. That said, it definitely does make sense to possibly be the battery. The more I think about it, such a blip of an issue does lead me down the road of being somehow electrical/computer in nature.

With the age of the battery I certainly can’t say it owes me anything. So, I’ll head out this weekend and buy one.

 

[Burla]

Well battery is spark and about responsible for 50% of all minor engine issues, maybe more. Capacity versus battery life is what gets most guys, you get the well I charged it and it's full all the time, yeah but after age the capacity is down.

Effect of cold and warm on capacity and battery life... If it is oem, for sure a possibility being in a decently cold spot.

Look what -10c or 14f does to capacity, the battery will last forever, but the capacity is 50%.

 

[Dusty]

Kind of a weird one here. I did search around on the forum to make sure I wasn’t double posting, but couldn’t find anything quite like what I experienced today.

A little background:
2017 Ram 1500 Sport 5.7 Hemi
~85,000 well maintained miles

Have always run the “recommended” 5w-20 changed at 7k intervals

Bone stock (only things that may be slightly different with the “sport” than other trim packages is a mopar CAI and “performance” exhaust, but again both are original to truck)

The only existing issue that I am aware of on the truck is the leaking exhaust manifold. Believe mine is only on the passenger side for now. I have had the ever so common “cold tick” for about 20k miles now (of course it started just outside of warranty) and as this truck is the 2nd 4th gen 1500 I’ve owned with the same issue, I’ve just chosen to ignore it.


ANYWAYS

I’m hoping someone could provide some insight as to how to go about diagnosing the issue I experienced today.

I can only describe it as an EXTREMELY rough idle. I had been driving for over an hour already, so it was all the way warmed up. Put in in park to get out and get the mail upon getting home. As I was sorting through junk mail at the end of the drive, the truck began to idle very rough. Far more than a miss. RPMs would dip to nearly a stall, and fire back up to over 2 grand every 10 seconds or so. Also sounded like some knocking and other awfulness. Feathered the accelerator to no effect, like it wasn’t even there. It sounded and acted bad enough that I was truly worried I would be pushing it the rest of the way down the driveway. No trouble lights on the dash at all. Shut it off, checked the basics (motor still contained oil, nothing is on fire). Went to start again, same rough idle and no throttle response. Waited about 30 seconds, started again….no issue.

Curiously, instead of heading down to the house like I probably should have, I backed out of the drive and drove about another 5 miles to see if the issue reoccurred. Multiple times stopping, parking, idling, and even cycling the ignition. Could not recreate the issue.

Drove back home and hooked up the code reader, I use v-linker with an app that displays all ELM327 data. No DTCs whatsoever, like the truck never even knew anything was wrong.

Just curious if anyone here has experienced anything similar and if so had any luck diagnosing.

Thanks in advance!

No codes? I would suspect another scanner would find one.

However, I know of another Ram 1500 that had the same symptom and it turned out to be an intermittent purge solenoid.

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: 3 June 2018. Now at 87633 miles.

 

[Sherman Bird]

Yeah, still the original. Reads 12.2v on the multimeter though and the truck hasn’t seemed hesitant to crank or anything recently. Worth replacing anyways just due to age you think?

The static voltage means nothing. Inasmuch as a battery doubles as a huge capacitor, you have NO clue as to it's capacitance without a specialized battery tester. This capacitance (or lack thereof) is what gives computers so much grief. I am a professional tech, and check customers' batteries whenever they bring a car in. You'd be shocked how many have bad reserve capacitance, but will start the vehicle just fine. We can no longer think in yesteryear terms when it comes to diagnosing even the most basic items under the hood of modern cars. That applies to batteries too.

 

[mwaters97]

UPDATE:

Thanks to all for the suggestions and advice. Didn’t touch a thing for over a month, with no reoccurrence of the issue. However, all the ideas on here seemed like great suggestions on general maintenance. So with that a few weeks ago I changed the battery, cleaned the throttle body (it was fairly dirty with deposits and buildup) and tightened the intake manifold bolts (all were loose). Also ran sea foam in the fuel for three fill-ups in a row. I’ve seen a number of users here and on other forums running catch cans on their hemis, and it seems like a good idea. Upon cleaning the throttle body, there was a light film of motor oil on the bottom side of the valve, as well as in the manifold. Think that catch can will be my next project here shortly.

Thanks again to all, and I’ll continue to update if anything changes!