2019 Classic - Rough idle on cold start.

[NCRaineman]

Hey all. First issue I've had out of my 2019 Classic. When I start it after having sat for a few hours the engine cranks but it struggles to idle for the first minute or two. Once running it drives fine. On warm restarts it fires right up and idles smoothly.

No CEL (that would be too easy) no ticking or knocking that would suggest an internal problem. I gave the top end a quick once over and didn't notice any loose wires or cracked hoses that might cause a weird sensor reading or vacuum leak.

Would a low battery cause this? It's still got the original one so we are at the 5 year mark. I don't mind replacing it, but at the same time don't want to spend $300 on that if it's not the problem. Voltage screen in the dash indicates 12v when the engine is off. On startup it is dropping to 10 then climbing to 14 as the alternator kicks in.

Your thoughts are appreciated.

 

[Bigskyroadglide]

How many miles? Could be dirty tb, iat sensor or any number of potential electrical items.

If low miles, would think electrical, if high miles dirty tb or iat sensor. Both of which can be cleaned

Might want to run some redline fuel treatment through the tank if close to your oil change interval

 

[NCRaineman]

How many miles? Could be dirty tb, iat sensor or any number of potential electrical items.

If low miles, would think electrical, if high miles dirty tb or iat sensor. Both of which can be cleaned

51k miles. My wife mainly uses it for commuting, which is a whole three miles each way.

Had the oil changed at the dealer at 50k. Truck has gotten 89 octane since new. I took it out this afternoon and did the old "Italian tune-up"... seemed to pull fine. I'll probably slug a bottle of injector cleaner through it the next time we get gas, couldn't hurt at this point. My wife drives pretty gently so the engine doesn't get much time above 3k RPM.

 

[Bigskyroadglide]

Suggest it probably throttle body that may need cleaning. Easy to do. Especially if she drives it easy. If you are going to use injector cleaner. Get

Red Line Redline S-1 Fuel Treatment: Complete Fuel System Cleaner, Gas & Injector Additive Treatment, 15 oz. Any major parts store should have in stock, about 15 bucks.

Easy to start there then move to more expensive items

 

[Wild one]

51k miles. My wife mainly uses it for commuting, which is a whole three miles each way.

Had the oil changed at the dealer at 50k. Truck has gotten 89 octane since new. I took it out this afternoon and did the old "Italian tune-up"... seemed to pull fine. I'll probably slug a bottle of injector cleaner through it the next time we get gas, couldn't hurt at this point. My wife drives pretty gently so the engine doesn't get much time above 3k RPM.

If you pull the throttle body to clean it,disconnect the negative post on the battery first,then do a key on / pedal to the floor / key off ,to do a throttle body relearn

 

[NCRaineman]

Updating. Got a video of it this morning.

2019 Ram Classic rough cold start.

2019 Ram Classic rough cold start.

youtu.be

This is accompanied by thick white smoke from the exhaust, which I can tell from the smell is fuel. The computer is adding a lot of fuel at startup to try and keep it running. As we see, after about 30 seconds it smooths out and proceeds to idle fine.

I haven't checked the throttle body yet, will pull the intake off and examine all of that thoroughly this afternoon once it warms up a bit outside.

 

[CanuckRam1313]

Check all the intake manifold bolts are securely in place.
This is a common thing to cause running issues.

I'd also pull the plugs and check them. Easy to do and could tell you a lot.

Definitely pull the TB and thoroughly clean it. Also, remove the PCV valve and clean it as well.

How's that CAI doing for ensuring that foreign debris isn't getting into the engine?

Toss in two bottles of RL SI-1 and top up with premium.
Take it out a fleece it... run the tank dry and refill with premium.
Then do an oil & filter change afterward.

With all the short trips, no doubt it's in "granny mode" all the time.
It's also not getting to full operating temps and being worked like a HEMI needs to be.

I'd do that above, and then take it out for a good long haul with several times getting into it and letting it rev out to its max (VVT hits at about 5,000rpm and shifts about 6,000rpm, or so...).
The HEMI needs to be spanked!

 

[Wild one]

Updating. Got a video of it this morning.

2019 Ram Classic rough cold start.

2019 Ram Classic rough cold start.

youtu.be

This is accompanied by thick white smoke from the exhaust, which I can tell from the smell is fuel. The computer is adding a lot of fuel at startup to try and keep it running. As we see, after about 30 seconds it smooths out and proceeds to idle fine.

I haven't checked the throttle body yet, will pull the intake off and examine all of that thoroughly this afternoon once it warms up a bit outside.

Put the stock airbox back on,your IAT sensor and throttle body don't like an oiled filter. Use a clean white rag to check the inside of your air duct for intake dusting.
And follow CanuckRams advice

 

[NCRaineman]

Put the stock airbox back on,your IAT sensor and throttle body don't like an oiled filter. Use a clean white rag to check the inside of your air duct for intake dusting.
And follow CanuckRams advice

That intake has been on there for the last 40k miles and I had the exact same one on my previous 2012 Ram. It's not the problem. It's fitted properly, the filter isn't over-oiled. The intake tube is dry and the MAF sensor is clean. Verified both of those things when I pulled the throttle body off.

The throttle body itself had a little soot around the butterfly. Nothing that I wouldn't expect to see after 50k miles. Cleaned that up with a little mild steel wool and blew everything out with compressed air before reinstalling.

Did the "throttle body relearn" procedure and it stumbled a little when I started it up again, but not nearly as bad as the first time. Went for a 15 minute drive on the back roads and fed her the onions a few times once it was warmed up. Pulls smooth all the way to redline just like it always has.

It's at about half a tank of fuel now. When it gets down to a quarter I'll slug a bottle of treatment in it and fill up. If it's still acting up next week or gets any worse I'll take it to the dealer. I paid for the extended warranty, they can deal with it. Just wanted to make sure it wasn't some silly simple issue that I could quick fix myself before making the 30 minite drive to town to drop it off.

Appreciate the tips, fellas. We will see what happens.

 

[Wild one]

That intake has been on there for the last 40k miles and I had the exact same one on my previous 2012 Ram. It's not the problem. It's fitted properly, the filter isn't over-oiled. The intake tube is dry and the MAF sensor is clean. Verified both of those things when I pulled the throttle body off.

The throttle body itself had a little soot around the butterfly. Nothing that I wouldn't expect to see after 50k miles. Cleaned that up with a little mild steel wool and blew everything out with compressed air before reinstalling.

Did the "throttle body relearn" procedure and it stumbled a little when I started it up again, but not nearly as bad as the first time. Went for a 15 minute drive on the back roads and fed her the onions a few times once it was warmed up. Pulls smooth all the way to redline just like it always has.

It's at about half a tank of fuel now. When it gets down to a quarter I'll slug a bottle of treatment in it and fill up. If it's still acting up next week or gets any worse I'll take it to the dealer. I paid for the extended warranty, they can deal with it. Just wanted to make sure it wasn't some silly simple issue that I could quick fix myself before making the 30 minite drive to town to drop it off.

Appreciate the tips, fellas. We will see what happens.

Your call,but i'd swap back to the original box,as you're not gaining anything with your hot air Air Raid box,except issues,the stock box actually is a cold air intake,while your Air Raid box isn't,it's a hot air box,as they don't seal worth a crap to the hood. Take a clean white rag and run it around inside the intake tube and see how clean it comes out.
BTW your 5.7 doesn't have a MAF sensor,it has a IAT sensor in the intake tube,and a MAP sensor on the back of the intake manifold.
I'd use Throttle Body cleaner instead of steel wool the next time you clean your throttle body,steel wool is a bit hard on the coating on the inside of the throttle body
Build a lid for your Air Raid box that seals the top,so it draws air from the fender.I'd also spring for a Filter Wears sock for the filter to keep the intake dusting down.

 

[NCRaineman]

Just to wrap this up for anybody who might come along in the future. After checking the fuel pump and injectors turns out it was bad gas. Dealer drained the tank and purged the lines, put a few gallons of fresh fuel in and she fired right up as normal. I stopped on the way home to put in a bottle of fuel system treatment and fill up the rest of the way with 89. Hopefully that will put the issue to bed.

I've got the write-up from the shop along with the bill to take over to the station I got fuel from. They owe me some money.