Vibration at 1500 rpm 6.4 hemi

[cc rider]

Ok. So I'm hoping it's not just my truck. Right around 1500 rpm I get a vibration in the engine. . It can be at any speed. Before I go into detail with this, anyone else notice it? It's very noticeable and I can get it to do it every time. You have to touch the gas pedal just right though

 

[tjfdesmo]

Not sure if we are describing the same thing, but mine gets a harmonic that causes a tinny rattle right around that RPM, maybe a bit less. Sounds like a heat shield, but I have not had a chance to track it down. Mine will sometimes do it just as the engine lights off at start up, as well.

 

[stoney]

There is some sort of a noise or vibration at low RPM, at first I thought it was the motor going into ECO mode, but since I turned on the ECO notification light on, I see that it is not what I thought it was.
Not too concerned, just seems like a flat spot in the HP/torque curve.

 

[cc rider]

Not too concerned, just seems like a flat spot in the HP/torque curve.

That's what I assumed. I was thinking about going and test driving another truck just to make sure it wasn't just mine. Idk, I'm a little concerned about it.

 

[cc rider]

I wouldn't call it a rattle. Harmonic , yes. Not sure what u mean by engine lighting off

Not sure if we are describing the same thing, but mine gets a harmonic that causes a tinny rattle right around that RPM, maybe a bit less. Sounds like a heat shield, but I have not had a chance to track it down. Mine will sometimes do it just as the engine lights off at start up, as well.

 

[tjfdesmo]

I wouldn't call it a rattle. Harmonic , yes. Not sure what u mean by engine lighting off

When starting the engine, just as it transitions from cranking to beginning to run. Often, as mine goes from cranking speed to fast idle it will go through that harmonic and cause the rattle I hear.

 

[cc rider]

When starting the engine, just as it transitions from cranking to beginning to run. Often, as mine goes from cranking speed to fast idle it will go through that harmonic and cause the rattle I hear.

Now I got u. I don't notice anything but the faster idling . Maybe I'll get it checked out or ask service guys when I take it in

 

[Searay245se]

I have noticed a little vibration around that rpm also and was wondering about it.

 

[cc rider]

I'm thinking they all do it. If my memory serves me correctly (which it never does) when I test drove one I might have noticed it too Maybe just a flat spot? If I hit tow/haul, it obviously will not be at that rpm and it goes away .

 

[regularcab2500]

Any updates on this? My truck has been doing this for a long time and until this thread it seems no one else has had this issue. The noise my truck is make sounds like its coming more from the rear of the vehicle. I have actually taken it to the dealership to have this problem diagnosed but they had a few other things to take care of and i couldnt go without my truck for 2 weeks straight at the time. I have had many people specifically say that its coming from the rear of the truck though.

 

[drittal]

Are we sure it isn't the MDS? My mds loves 1500rpm. Give it some gas and it goes away.

 

[WaterBoy1]

Are we sure it isn't the MDS? My mds loves 1500rpm. Give it some gas and it goes away.

I was just about to say the same thing! Almost like the slight "lugging" just before it kicks back to 8 cyl

 

[martian171]

mine does the same thing. I've noticed it doesnt do it on the highway and when its doing it, all i have to do is give it a little gas and it goes away. It's not a big deal, but its annoying me now. I feel that if it is infact the MDS it should be abel to switch without any vibrations or engine lagging. My truck only has 2200 miles on it, i'm thinking of getting to the 2500, 3000 mark and then taking it in and see what the dealer says.

Has anyone taken their truck to the dealer for this yet.... what was the outcome?

 

[WaterBoy1]

^ The GM motors with AFM (same thing as our MDS) transitions WAY worse! I was actually pleasantly surprised how the transition on these trucks is.

Not to offend any GM guys out there, that's not my intention, but these engines are a whole lot smoother.

I don't think the dealer is going to be able to help you any with this. I would say if it bothers you enough, you can tune it out with a Diablo or Blackbear tune.

 

[stoney]

Are we sure it isn't the MDS? My mds loves 1500rpm. Give it some gas and it goes away.

mine does the same thing. I've noticed it doesnt do it on the highway and when its doing it, all i have to do is give it a little gas and it goes away. It's not a big deal, but its annoying me now. I feel that if it is infact the MDS it should be abel to switch without any vibrations or engine lagging. My truck only has 2200 miles on it, i'm thinking of getting to the 2500, 3000 mark and then taking it in and see what the dealer says.

Has anyone taken their truck to the dealer for this yet.... what was the outcome?

I know I stated that it does not do it when truck goes into ECO mode, but I have been watching/listening to it more closely lately.
Seems to either happen just before or after the light goes on or off, not sure of the exact delay between the light coming off or on, but what I do notice is it seems to only do it at low speeds, at higher speeds it either does not do it or it is harder to tell, almost like at lower speeds the motor is chugging due to the drop in cylinders.

Just some food for thought.


Edit: I guess the test would be to turn off the MDS and see if it still happens.

 

[regularcab2500]

I can guarantee in my situation its not mds. It does it in manual mode and with tow/haul mode on. From my understanding, both of those functions disable mds.

 

[regularcab2500]

Last night i rotated my tires in the backyard. I only put the rear passenger side on a jack stand to do the rest. When i had the rear driver tire jacked up i decided to spin the tire a bit and heard a light grinding noise. It wasnt specifically in the diff, in fact it sounded like it was coming from inside the axle tubes, mostly the side i was spinning. Any idea if anyone else's makes funky noises? It almost sounded like there was debris or something in there.

 

[loveracing1988]

Last night i rotated my tires in the backyard. I only put the rear passenger side on a jack stand to do the rest. When i had the rear driver tire jacked up i decided to spin the tire a bit and heard a light grinding noise. It wasnt specifically in the diff, in fact it sounded like it was coming from inside the axle tubes, mostly the side i was spinning. Any idea if anyone else's makes funky noises? It almost sounded like there was debris or something in there.

First guess would be the parking brake shoes. If there is debris large enough to cause a noise in an axle tube you have bigger problems.

 

[regularcab2500]

Thats precisely what ive been worried about though lol. At least its still under warranty. Im just trying to get the evap system on my dads truck taken care of first before i have to be without mine for as long as they might need it.

 

[loveracing1988]

Thats precisely what ive been worried about though lol. At least its still under warranty. Im just trying to get the evap system on my dads truck taken care of first before i have to be without mine for as long as they might need it.

No, I'm more saying there would be something seriously wrong that you would have noticed before you noticed the scraping noise. If you want to eliminate the axle tube pull the bolts out of the axle shaft and spin the tire, if you still hear the noise it is either in the brakes or the hub bearings, and I highly doubt it is the hub bearings because in 5 years of testing those axles I have yet to see one go bad.