5.7L bogging down under load and low rpm

[chidychi]

Hi everyone.

5.7L with 66RFE
I have a 2017 2500 slt with about 200k km (125k miles). I've searched the forums but haven't quite found my situation.

About a year ago, the truck started to struggle climbing hills ( my driveway is a 300' hill with turns covered in ice and snow) . I parked it for about 6 months with the intention of getting back to it.
After about 6 months, I fired the truck up and it ran fine.
After driving it the last 6 months it has slowly started to bog down. Seems to be getting worse. Odd that it sitting seemed to solve the problem for a time.

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Symptoms ( I live in cold climate and mostly drive the truck in winter):

When engine is Cold:
- Starts fine, seems to back up slowly fine, I put it in drive and it will move without throttle. But (sometimes) if I give it any throttle it will bog down.
- Acceleration from stop is terrible when cold.

When engine is Hot:
- Light pressure on throttle bogs down. Continues to bog down until I hit about half way on the throttle. It drops a couple gears and it accelerates a little too well. Doesn't seem to matter which gear I'm in. If it doesn't drop a gear it won't accelerate)
- If I'm climbing a hill in any gear, it will struggle until the rpm hits around 2500 - 3000. After that it wants to go.

General:
- When it downshifts it usually skips 2 gears and feels like a race car..... whether I want it or not. I am putting in a new valve body soon.
- I cleaned the TB yesterday. Didn't seem to help. Noticed oil in the intake. I'm assuming that is from the PCV when i need to punch it to climb a hill.
- I cleaned the PCV yesterday. Seems fine.
- new air filter.
- When not in gear it seems to rev fine.
- very slight fluctuations in rpm when travelling at steady speed.
- gas mileage has **** the bed hard.
- Cam shaft tick. Planning on fixing that soon.
- NO CODES. No stuttering. No shaking. Just no power at low rpm.

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At first I thought all the problems were due to the tranny. I'm going to replace the valve body and replace the tranny oil soon. But now I'm wondering if the bogging is an engine issue instead.

Any help would be appreciated.

 

[crackerjack1957]

How many miles on spark plugs?
If 125K....... change them.

Check your intake bolts.

Check your intake manifold bolts

This hasn't been talked about for awhile,but check your intake manifold bolts.They call for 108 in-lbs or roughly 9 ft-lbs of torque,and they should be checked at least yearly,as they do loosen up. I've been doing mine at least twice a year on all 3 of of my hemi equipped vehicles.They should be...

www.ramforum.com

 

[Wild one]

If it has a camshaft tick,you might want to investigate that first.Alot of what you're describing could be attributed to a camshaft going south.

 

[chidychi]

How many miles on spark plugs?

Sorry I should have mentioned. They have about 5k on them at most.

If it has a camshaft tick,you might want to investigate that first.Alot of what you're describing could be attributed to a camshaft going south.

As soon as the weather clears up a bit here I'm going to start on that. I just need to gather parts and recommendations on what else I should fix while i'm elbow deep in'er.
The only odd part if that is the culprit is that there are no codes, no misfires, no rough idle etc.... However that's definitely the leading theory in my mind (Other than the tranny)

Check your intake bolts.

I'll go take a look right now.

Thanks guys!

 

[chidychi]

Some of the bolts on the intake manifold were slightly loose. I tightened them but it didn't seem to change any of the symptoms.

 

[chidychi]

So last fall I replaced the exhaust manifolds because they had broken bolts. Ticking never stopped.
Today I took off the valve covers, and both banks looked fine.

I did what any idiot would do in 2024. I asked ChatGPT.... It said that a loose timing chain could cause the ticking... or piston slap.

I guess the next step would be to examine the timing chain and maybe pull out the cam to examine it as well... unless anyone has a better idea?

 

[chidychi]

Actually,
Maybe I'll look into the valves first:

Hesitation at low rpm and fuel system goes to open loop

2012 Dodge ram with 208,000 kms. For the past year randomly around 1000 to 2000 rpm and 5th or 6th gear with MDS deactivated it just won't rev or build power be eventually it will drop a gear and about 10 to 15 seconds later just take right off. I bought a Blue Driver scanner tool. No check...

www.ramforum.com

 

[GTyankee]

That transmission, has 2 filters in it
One of the filters, can be different, depending on whether the truck is a 4X4 or not. So inform the person selling the filters whether you have the 2x4 or 4x4

 

[RAM72]

Hi chidychi. It seems as though I may have the exact same issue as you. My 2012 Ram 2500, boggs at low rpm then seems to go into passing gear or something. A bit embarrassing when I'm just driving around town. Lol. Changed the plugs and coils as I figured it was a misfiring issue and I'm just over 200,000 KM. No codes show up though. Also got the ticking at the same time. All started after I towed our 5th wheel for the first time with this truck. Wondering if you found the issue?

 

[chidychi]

Hi RAM72
I'm in the middle of taking the heads off the engine to inspect. I'm not very motivated as this is my plow truck and I don't really need it until November. I'll probably have an answer to your question by the end of June if I'm lucky.

I think I have the same problem as outlined in this thread: https://www.ramforum.com/threads/he...-system-goes-to-open-loop.155766/post-2897291
It's all very strange. I'm gettting about 7 MPG (35 L /100 KM) on the highway and it's under full load (bogs down) in my driveway on level ground.
Compression seems fine on all cylinders. No codes.
This engine had a ton of idling at it's previous owners. However, inspecting the valve springs with the valve covers removed showed no obvious signs of lifter/cam lobe damage.

I'll update this thread once I start looking at the valves/rods/lifters.

 

[rzr6-4]

@chidychi @RAM72

Mine does the same thing as well. Seems like a number of people on the forums here have had the same issue but no one has been able to determine the cause/fix.

I've done air filter, cleaned PCV hose and intake, replaced MAF sensor, and cats are now bluetooth because I thought maybe they were clogged.

Muffler rusted out so I'll be redoing the exhaust in the next couple weeks but plugs & tranny fluid are both on the short list after that.