2019 Classic, no low end torque

[hunterdan]

My 19 classic hemi has been puzzling me for a while. The thing idles smooth and fairly quiet. There's no noises that concern me. The fuel mileage has been abysmal, especially for stock sized tires. I'm currently sitting at 106k miles. Original plugs. Like I said, idles smooth as glass. 3.21 gears. The thing feels like a dog off the line, until 3500 rpm then it rips. The problem is, when cruising on the highway or any road for that matter. When your cruising at 1500-2000 rpm, if I hit even the slightest of inclines, it bigs down and has to downshift. It can't hold the gear, it requires a lot of throttle input. My older Silverado with the 4.8 seemed to have better low end and didn't struggle like this. I don't believe it was always like this.
Now, yes it's due for spark plugs. But, I can't believe they'll make a huge difference in performance if I'm not misfiring. The tires are stock size, on a small level. I actually went back to a stock sized tire trying to see if that would fix the issue. It clearly did not. I know the 3.21 gears don't help, but again, stock sized tires 275/60r20.
Gummed up intake? Bad O2 sensors? SRV not actuating fully? I don't expect this thing to get 25 mpg on the highway, but I should be getting better than 14 on mostly highway trips. I know my front bumper isn't helping, but again this issue has persisted before the bumper was installed.
I'll probably pull the throttle body off this weekend, clean it and try and get a good intake cleaner and let it soak for a few hours. At least that's where I plan to start before digging deeper and going more intrusive. I know it could use plugs, but again they might gain me 1-1.5 mpg, if that. And if I'm going to be pulling things and cleaning, I'd rather do all the cleaning first, then the plugs.
Where would you start? What would you look into? I have an OBD2 scanner, what would you check?

 

[ramffml]

Why not change your plugs first?

It will have absolutely nothing to do with 3.21 gear ratio if you're noticing this at speed on the highway.

 

[EdGs]

I wonder if a throttle relearn would help?

 

[CanuckRam1313]

Spark plugs, yes!

Throttle body service (remove completely and clean thoroughly), then do a TB relearn, and take out the PCV valve & clean it or replace it altogether.

(while cleaning the TB) Check and tighten all your intake manifold bolts (these are known to loosen up and cause issues).

If you're wanting to do a thorough intake cleaning though, remove it altogether, degrease it and power wash it, then reinstall.

I'd toss in a couple of bottles of Red Line SI-1 fuel system treatment, fill with premium and run to empty, then refill with premium and run to dry, and then do an oil & filter change, and then use premium for a while.

You could also run a full can of Seafoam through the brake booster vacuum lime while someone holds 2000rpm and you siphon off the top of the can (not directly into the liquid) so you create a mist like action and drain the can dry. Let it sit for 10 to 15 minutes, and then take it out and drive it like you stole it until there's no more fog coming out the tailpipe (you'll definitely want to change your spark plugs after that service).

How do you typically drive, in terms of, do you drive spiritedly and work your HEMI like it needs to be?
Perhaps your adaptive learning has put your truck into "granny mode"?

I had a 19' Classic Hemi with 3.21's that ran flawlessly and with lots of pep, too!

 

[kurek]

Might be a long shot but a few years ago I started having a symptom of just gutless and unresponsive power at low RPM & seemed to be about normal once the RPM got up over 3-4k .. I know we have variable cam timing and variable intake geometry so I thought maybe there was a problem with those but I didn't get any codes when I scanned with JSCAN.

This was on a 2015 hemi with the RFE transmission and 3.55 gears, under 50k miles.

Then as fast as the problem arrived it disappeared and I have a hunch why: I had topped up my fuel tank at a brand I never use & the next tank as well. The following tank I went to my usual convenient station & the truck was back to normal almost immediately. Never went back to that brand, never had the problem return.

I think maybe the fuel I got from them didn't play nice with my truck. I'm fairly experienced under the hood but don't have enough data to speculate on exactly what was wrong about that fuel and it could have been a coincidence entirely unrelated to the fuel. It doesn't matter I just don't buy fuel there anymore.

Anywhere else the truck really doesn't seem picky, I don't have a brand preference or location preference just whatever's nearby when the needle points toward E. I almost always fill on 89 or higher octane as recommended in the owners manual.

Sorry that's a lot of words I just want to share as much detail as possible in case this is helpful.

Maybe try a tank of fuel from a different supplier. And if your plugs are due and you know it, change them - it's always ideal to eliminate variables when chasing a problem.

 

[Wild one]

When you do the plugs also do some maintence on your coils and injectors.
As stated it might not be a bad idea to pull the intake manifold off and give it and the intake ports a good cleaning,especially if you don't run a catch can,and replace the intake gaskets while you're at it.
If you're removing the throttle body to clean it,disconnect the negative battery post first.

Coil cleaning pics

Yea i know my picture taking abilities suck,lol Hopefully you guys can tell how i go about cleaning up the coils from the pic's. The first pic,is just a pic of everything disassembled.If your truck has the resistors under the spring in the coil towers,you'll want to remove them and clean them...

www.ramforum.com

Injector cleaning

Supposed to go cold and snow for the next 10 days,so i figured it was a good time to pull the injectors and give them a cleaning.Got them soaking in injector cleaner,where i'll probably leave them for a couple days before using some carb and choke cleaner to wash them out using my old homemade...

www.ramforum.com

 

[Mojo88]

Spark plugs, yes!.................

Might be a long shot but a few years ago I started having a symptom.............

I think if you follow recommendations in those two posts, you have a good chance of restoring lost power. Maybe add the suggestions from @Wild one too, if you're in that deep.

I didn't see 'air filter' mentioned anywhere, so that's another item that could be due for change.
Keep us posted...............

 

[hunterdan]

Air filter is newer, it's been replaced in the last few months. This isn't a new problem. It's something I've been noticing over the past 2 years or so. I first noticed it after changing brakes and initially thought it was my brakes dragging. But I went through and verified my brakes aren't dragging. All the wheels spin freely, no drag on them. Have even checked the temperatures after driving and there was nothing crazy or abnormal. I think it was just that I was more in aware with what was going on after I did the brakes.
This weekend I'm going to pull the throttle body, do a relearn and try to clean the intake manifold using some cleaner. I do have a catch can. But a few years ago I forgot about it and didn't drain it for several months so it was over full and probably sucking in more than it should have. So, my thoughts are that it really needs a good intake cleaning. My driving style is mixed. I get on it and drive it spirited and open the throttle up, but I also don't constantly beat on it. I've thought about pulling the intake manifold and doing a thorough cleaning, but since it's been sub-freezing temps lately, I might have to wait until spring to do that. If I go that route, I might look into seeing what it'd take to do the 6.4 manifold swap since I'd have it out any way.
I'll be off work for a few weeks before and after Christmas, so I'll probably order a set of spark plugs and tackle that in the next few weeks.

 

[Wild one]

Air filter is newer, it's been replaced in the last few months. This isn't a new problem. It's something I've been noticing over the past 2 years or so. I first noticed it after changing brakes and initially thought it was my brakes dragging. But I went through and verified my brakes aren't dragging. All the wheels spin freely, no drag on them. Have even checked the temperatures after driving and there was nothing crazy or abnormal. I think it was just that I was more in aware with what was going on after I did the brakes.
This weekend I'm going to pull the throttle body, do a relearn and try to clean the intake manifold using some cleaner. I do have a catch can. But a few years ago I forgot about it and didn't drain it for several months so it was over full and probably sucking in more than it should have. So, my thoughts are that it really needs a good intake cleaning. My driving style is mixed. I get on it and drive it spirited and open the throttle up, but I also don't constantly beat on it. I've thought about pulling the intake manifold and doing a thorough cleaning, but since it's been sub-freezing temps lately, I might have to wait until spring to do that. If I go that route, I might look into seeing what it'd take to do the 6.4 manifold swap since I'd have it out any way.
I'll be off work for a few weeks before and after Christmas, so I'll probably order a set of spark plugs and tackle that in the next few weeks.

If you don't have one of each of these,they're well worth picking up,they make doing the plugs alot nicer on a hemi.

Amazon.com

https://www.amazon.com/GEARWRENCH-Drive-Extension-1-1-81240/dp/B002YKE16S?crid=376E5M1LP62P&dib=eyJ2IjoiMSJ9.No9qocrEE_VldFimbS-gDNmuDgoT8YJWgM34f0QWkmvXs-YywxH0qjGHN_wOGJJYBqml7T4_3ABrCr3cU0d3DCu89f4BhB2hpmZDQhITKzexOCD9CysZsBGy92G4GDkIwRqjl6QV3UycSEVDUbMQxyL73p8lKv7EzJy4xK36pl5SE6itkUyrLYpQ-1epztvhVk1MKhgHkCpUH0S8_Zil9nLXIt-H4h78P72M7iHXQ6CcUMMkwDv1iO5QpEBkiPq6ljUjvaqEYMESw-HrspA4rTdpwD-OdRg4_PABDKC6jQ8.ZHc6BzwPBdeV9FHzXcyGS3xfmtda02u9Vf4IlYSTiDo&dib_tag=se&keywords=1.5%22%2Bextension%2Bin%2B3%2F8%22%2Bdrive&qid=1765406410&sprefix=1.5%2Bextension%2Bin%2B3%2F8%2Bdrive%2Caps%2C161&sr=8-30&th=1

 

[CanuckRam1313]

Air filter is newer, it's been replaced in the last few months. This isn't a new problem. It's something I've been noticing over the past 2 years or so. I first noticed it after changing brakes and initially thought it was my brakes dragging. But I went through and verified my brakes aren't dragging. All the wheels spin freely, no drag on them. Have even checked the temperatures after driving and there was nothing crazy or abnormal. I think it was just that I was more in aware with what was going on after I did the brakes.
This weekend I'm going to pull the throttle body, do a relearn and try to clean the intake manifold using some cleaner. I do have a catch can. But a few years ago I forgot about it and didn't drain it for several months so it was over full and probably sucking in more than it should have. So, my thoughts are that it really needs a good intake cleaning. My driving style is mixed. I get on it and drive it spirited and open the throttle up, but I also don't constantly beat on it. I've thought about pulling the intake manifold and doing a thorough cleaning, but since it's been sub-freezing temps lately, I might have to wait until spring to do that. If I go that route, I might look into seeing what it'd take to do the 6.4 manifold swap since I'd have it out any way.
I'll be off work for a few weeks before and after Christmas, so I'll probably order a set of spark plugs and tackle that in the next few weeks.

I'd bet you have some cascading issues with the overfull catch can dumping oil into the intake manifold back then and now its just accumulated and sludged the heck out of everything, and your TB will likely be black as tar, too.

I'd also just replace the PCV valve altogether, based on what you've indicated above.

If you're not going to remove the intake manifold now, then before the TB cleaning, run a full can of Seafoam through there, then clean the TB and replace the spark plugs afterward, too! But, do check all the intake manifold bolts and tighten as per spec!

I would definitely be dumping in two bottles of Red Line SI-1 fuel system treatment in as well!

Regarding the 6.4 intake manifold upgrade.... unless you're doing other upgrades I'd leave it alone and spend your hard earned dollars elsewhere.

You gains would be negligeable at best with that upgrade alone and with little to nothing upgraded to compliment it, what's the point? A lot of cash and effort for virtually zero gains on a stock 5.7... just my opinion though!

 

[hunterdan]

I'd bet you have some cascading issues with the overfull catch can dumping oil into the intake manifold back then and now its just accumulated and sludged the heck out of everything, and your TB will likely be black as tar, too.

I'd also just replace the PCV valve altogether, based on what you've indicated above.

If you're not going to remove the intake manifold now, then before the TB cleaning, run a full can of Seafoam through there, then clean the TB and replace the spark plugs afterward, too! But, do check all the intake manifold bolts and tighten as per spec!

I would definitely be dumping in two bottles of Red Line SI-1 fuel system treatment in as well!

Regarding the 6.4 intake manifold upgrade.... unless you're doing other upgrades I'd leave it alone and spend your hard earned dollars elsewhere.

You gains would be negligeable at best with that upgrade alone and with little to nothing upgraded to compliment it, what's the point? A lot of cash and effort for virtually zero gains on a stock 5.7... just my opinion though!

I've got a couple weeks off coming up, so the truck can stay down for a few days if need be, plus the wife will be recovering from surgery, so she'll be home and not be driving anywhere. So, i may just pull the intake and soak it in a container of degreaser to see how much junk comes out. I've never pulles an intake manifold off any vehicle, so I'm hesitant. But it doesn't look to be that hard to do on these trucks. Figure while it's soaking I'll swap out the plugs and and have a fresh set of intake manifold gaskets on hand to swap in as well.

 

[Wild one]

I've got a couple weeks off coming up, so the truck can stay down for a few days if need be, plus the wife will be recovering from surgery, so she'll be home and not be driving anywhere. So, i may just pull the intake and soak it in a container of degreaser to see how much junk comes out. I've never pulles an intake manifold off any vehicle, so I'm hesitant. But it doesn't look to be that hard to do on these trucks. Figure while it's soaking I'll swap out the plugs and and have a fresh set of intake manifold gaskets on hand to swap in as well.

Soaking it in degreaser is good,but a tub of gasolene is better,then take it to your local carwash and pressure wash the hell out of the inside of it. Odds are your intake ports will need cleaning to,i've used everything from brake clean to gasket remover to get them clean,depending on how badly caked up they are

 

[hunterdan]

Soaking it in degreaser is good,but a tub of gasolene is better,then take it to your local carwash and pressure wash the hell out of the inside of it. Odds are your intake ports will need cleaning to,i've used everything from brake clean to gasket remover to get them clean,depending on how badly caked up they are

Yeah I figured I'll probably be cleaning the intake ports as well.
I'm assuming changing the spark plugs would be pretty easy with the intake manifold out, so might just swap the plugs once the manifold is out and soaking.
Thinking I might pull the front tires, throw the front end on jack stands as low as I can to make reaching into the engine bay as easy as possible. Not sure why i dread doing this job, I've been an industrial maintenance mechanic for 20+ years. I've taken far more complicated stuff apart. I guess the difference is if I screw up it's my money and not the company's.

 

[Wild one]

Yeah I figured I'll probably be cleaning the intake ports as well.
I'm assuming changing the spark plugs would be pretty easy with the intake manifold out, so might just swap the plugs once the manifold is out and soaking.
Thinking I might pull the front tires, throw the front end on jack stands as low as I can to make reaching into the engine bay as easy as possible. Not sure why i dread doing this job, I've been an industrial maintenance mechanic for 20+ years. I've taken far more complicated stuff apart. I guess the difference is if I screw up it's my money and not the company's.

The manifolds are easy to take off,and the beauty is they don't weigh anywhere near what an old cast iron intake weighed, . While the intake is off,it's a good time to pull the vvt solenoid and look it over for any shiny flakes,as it's a good indicator of how healthy your cam is.

 

[hunterdan]

The manifolds are easy to take off,and the beauty is they don't weigh anywhere near what an old cast iron intake weighed, . While the intake is off,it's a good time to pull the vvt solenoid and look it over for any shiny flakes,as it's a good indicator of how healthy your cam is.

You mean see how long I have before I decide to trade it in?

 

[Wild one]

You mean see how long I have before I decide to trade it in?

19's were the last year of the well built 4th Gens,after covid hit,they went to $h!t in my opinion

 

[hunterdan]

19's were the last year of the well built 4th Gens,after covid hit,they went to $h!t in my opinion

Speaking of vvt solenoid, if that were dirty with just sludge and not metal flakes or anything, could that cause any of the issues I'm seeing and not throw any codes? Or would that throw fault codes?

 

[RamDiver]

19's were the last year of the well built 4th Gens,after covid hit,they went to $h!t in my opinion

I don't think that's true, because aside from a failed door lock solenoid, a clock spring and harness (the clock spring failure may have cooked the harness or the other way around), my truck has given me just over 40K miles of joy with zero grief. I feel very lucky.

And the recent addition of a Pedal Commander has significantly increased the fun factor.

The crappy workman$hit must have started sometime after April of '21.

.

 

[Wild one]

I don't think that's true, because aside from a failed door lock solenoid, a clock spring and harness (the clock spring failure may have cooked the harness or the other way around), my truck has given me just over 40K miles of joy with zero grief. I feel very lucky.

And the recent addition of a Pedal Commander has significantly increased the fun factor.

The crappy workman$hit must have started sometime after April of '21.

.

I think they have more electrical issues after 19,but that's just going by the amount of guys on facebook and here having electrical issues.Mechanically they're not much differant. But electrically i think the quality of wiring etc. went downhill when covid struck,as every manufacture was scrambling to get enough wiring and computor components to build their vehicles

 

[Wild one]

Speaking of vvt solenoid, if that were dirty with just sludge and not metal flakes or anything, could that cause any of the issues I'm seeing and not throw any codes? Or would that throw fault codes?

I'd think you'd have a code if the vvt solenoid wasn't operating properly,but maybe if all it is ,is sludged up,it wouldn't throw a code,but if it's sludged up to the point it's not letting oil through the screens,i'd think the whole engine would be full of sludge,and something would throw a code.