Intermittent power reduction, RPM hang when turning/going uphill

Maintenance/Repairs
1

This post is probably going to ramble. I want to give as much information as possible to have the best chance of receiving help.

I have a 2011 Ram 1500 Laramie. I purchased it almost 2 years ago now. For the first 6 months it ran beautifully. Then I started having issues that have gotten progressively worse. I’ve been to 3 mechanics, and posted on a few different forums trying to get some help. I live in a pretty small town, so my diagnostic options are limited and its my only vehicle. Most of the auto shops around here are pretty basic. They want to throw parts at it and pray. I don’t have that kind of money.

Sometimes the truck runs great. I can accelerate quickly and drive down one road with full power, and then turn onto another road and suddenly the RPMs hang at about 2k and my exhaust note drones. My speed slowly increases, but my RPM does not. If I hammer the gas pedal another inch down it will wake up and take off like a 400HP engine should. This is usually accompanied by a little pop, I’m assuming from the tailpipe. But its pretty dangerous to do because it jumps from 2k to 4k RPM real fast and the back end gets loose. Its pretty bad when it happens on a freeway ramp.

I seem to notice it more after turning, and when going uphill. It does it in cruise control too. I’ll be coasting along at 70 on a flat road, and when I hit a small hill it will lose 4-5 mph and drone the same tone before gunning it up the rest of the hill. I imagine if it was a little slicker outside it would be dangerous.

Sometimes when I start my truck it roars to life (flowmaster outlaw exhaust) or it sounds kind of weak and muffled. Sometimes it roars when I accelerate from a stop, or sometimes it sounds weak and muffled.

Most of my driving is to and from work (4 mile round trip). I rent a vehicle for vacations usually, because I’m afraid my truck won’t make it all the way there. Last night I took a 150 mile round trip in it. All of the problems I’ve described seemed to get worse the longer I drove it. Like something heats up and makes it worse.

I think thats about everything I can say to describe the problem.

I’ve replaced all 16 spark plugs, cleaned the throttle body, changed the air filter, tried different octane levels of fuel, tried different brands of fuel, ran techron or other fuel treatments through it more than once, replaced the gas cap, which seemed to help for a few days before it started running rough again. I’ve tried two different types of oil recommended for the smooth operation of the hemi MDS engine.

At one point I thought it was the transmission, but a local mechanic said he felt it shifting fine. His theory was that the truck was becoming stuck in 4 cylinder eco mode, but there are two ways to drive the truck without MDS activating and it still does the same thing. I ran it in tow/haul mode, and it still bogs down randomly. I ran it in 5th gear and it still does it.

I have never had a check engine light come on, and the only code I get from scanning is a radio region mismatch for my satellite radio.

My most recent theories are a fuel delivery problem, or an exhaust restriction. But without a trouble code its hard to justify throwing money at an in tank fuel filter/pump combo, or new catalytic converters.

I’m hoping someone out there has experience with a similar problem.

2

As you posted, throwing parts at it is fruitless and expensive.

If you want to fix this, you need a mechanic that can ride with you with a scanner, that he knows how to use, so he can diagnose this issue. If there is none in your town, go to a town that has one. There is no magic fix, as you found on other forums.

You have lived with this for 18 months. Take steps to fix it, or trade for something that works.

3

In my mind, that says transmission. If the RPMs stay the same while the car gradually accelerates that indicates slippage in the drive train. When was the last transmission service? Have you checked the fluid lately? Is there a transmission shop anywhere near you? That’s my 2 cents.

4

Dave, I have to disagree with you. If the transmission was slipping the rpms would increase and the car speed would not. I think what the OP is describing is the engine lugging while the transmission is in too high a gear. When it “breaks loose”,it sounds like he’s describing a normal forced downshift that he’s not accustomed to.

4 Likes
5

That’s entirely possible but if the transmission isn’t slipping the RPMs should increase as the vehicle’s speed increases, which apparently isn’t happening. Either way, the OP needs to have the transmission looked at IMHO.

1 Like
6

That actually sounds pretty plausible. Why would it only happen after turning though?

7

You’ve slowed for the turn, the vehicle was in high gear, accelerating out of the turn, with the MDS stuck in 4 cyl mode, you’re simply lugging the engine and not getting enough power, you push the accelerator harder until a downshift is forced.

8

It does the same thing with MDS disabled though. I got a video of a short drive I took a few minutes ago. I’ll upload it soon. Maybe it’ll help.

9

I would question if the MDS is actually being disabled. It’s a very complex system and is known to be somewhat troublesome. This needs a tech riding with you with a scanner capable of reading live MDS data.

10

It lugs at about 1:35. Before that I took two turns without an issue. It was raining so I didn’t want to get too crazy.

11

Next time, before you accelerate out of the turn, use the autostick feature to downshift to 3rd, ill bet it feels a lot more responsive.

1 Like
12

This is a common complaint on many late model vehicles, the transmission controler is programmed to hold higher gears after slowing then acceleration in the interest of fuel economy. When road testing customers vehicles I usually push the accelerator passed half throttle after making a rolling right turn to force a down shift.

The vehicle operation in the video looks completely normal, the truck went from 15 MPH to 55 MPH at part throttle in 10 seconds at an economical engine speed, no reason to race the engine or to accelerate more rapidly in the rain.

13

I really don’t mean any offense by this, but I’m tired of people telling me its a feature. It never used to do this and its dangerous in certain situations. Namely freeway entry. I can’t safely get up to speed and enter the freeway without a sudden jump in rear end torque and my traction control has turned on more than once. After traveling for an hour or two it loses accelerator response to the point of not even being able to hear the exhaust when I accelerate. Thats what led me to think I have some kind of exhaust restriction.

I’m not a lead foot driver. I’m not trying to drive fast. I’m just trying to accelerate with the flow of local traffic and sometimes I can’t keep up when this happens. My buddy at work drives a 4 cylinder car with the top speed of a lawn mower and blows past me at green lights on the way home. I shouldn’t have to gun it to 80% throttle to get a response. Winter is coming (get it?) in Michigan and its not very fun to drive in when your acceleration is inconsistent. My 2WD blazer drove better than this.

I think its one of those things you just have to feel to understand.

14

Could possibly be a drive by wire sensor or throttle body problem, but I’d think you’d get a check engine light and code. I think you’ll have to get someone with a scanner reading the data as it happens, like someone else mentioned. That’s about all I can offer. Otherwise, it’s expensive parts throwing time! And nobody wants to do that.

1 Like
15

I think that’s my only option unfortunately. There’s a Dodge dealer about 30 miles away, but that was my last resort. They have quoted me some insane prices in the past for simple jobs. I was hoping it was something I could fix on my own.

16

It is not a feature, it is a measure taken to satisfy those who voted for the guy that pledged to increase the fuel economy requirements of vehicles sold in the United States.

There are software updates to address MDS operation and transmission shifting enhancements but the service bulletins do not state that the update will improve down shifting but perhaps it is worth a try.

3 Likes
17

I’m willing to try anything at this point. I want my truck back the way it was!

18

You could possibly check for a plugged cat converter on your own, or have a shop test the exhaust backpressure when it’s acting up. Could be that one of the converter’s innards has broken and is bouncing around in there. If it turns sideways, you’d get the muffled/weak sound. If it orients itself back, you’d be roaring and running well again. If that were the case, you should be able to tap the converter(s) with a rubber mallet and hear the converter material rattling. Just a thought.

But if the truck ALWAYS accelerates well once you get into the throttle enough, I kind of doubt the converters are an issue.

19

I was torn between plugged cats and a fuel pump/pressure problem from gas sloshing after a turn. I want to say it runs better when the tank is full, but it still happens.

The Ram fuel filter is attached to the pump inside the tank, so that isn’t an easy driveway fix for a maybe. I’ve read every related forum post on all of google and now I’m basically grasping at straws to avoid the dealer.

20

The thing I’m hung up on is the different sound at idle. If it truly sounds different at idle sometimes…well, you’d think something isn’t quite right.

Try driving and shifting manually like someone else mentioned. If the acceleration is good with you controlling the gear, it may be the trans shift strategy. On most modern transmissions, the shift strategy “adapts” to how you drive. You could reset it or “undo” the learning by disconnecting the negative battery cable and turning the key to start the truck. This will reset the computer (removing the cable). Attempting to start removes any stored battery power. Or that’s how we did it back in the day when I owned a 98 Ram.