Slight shutter......

AZSCTACO · Jan 7, 2013

So I have a minor issue that I'm hoping to get some input or suggestions. I've noticed over the past couple of months I'm getting a minor shuttering when my truck is slowing down to either stop or turn. Before anyone says it's the rotors...it's not. It's definitely a drivetrain shutter....almost like it's a brief rough idle that's happening between 5-10 mph when I'm slowing down to stop.

One thing i did notice that it's more prevalent when it's colder outside.... definitely more in the morning (35-45 degrees) When it's warmer out....most of the time it won't even do it.

Some of things I thought of was either a motor mount, transmission mount, u-joints, torque converter. I changed out the throttle body/TPS this past weekend and that wasn't it.

Any suggestions?

Tahoe is an 07' LT 2wd 128K miles

Modded · Jan 7, 2013

Could be an engine mount. My friends Escalade had that issue and sometimes his 6.2: would hit the bottom of the hood because the mounts were so bad.

AZSCTACO · Jan 7, 2013

Thanks for the suggestion. I was reading some other threads and read that someone was having harsh/delayed 2-1 shifts while stopping.....I think that's what mine is doing as well. Could a bad motor mount cause that?

KMeloney · Jan 7, 2013

For a minor shutter, check out Blinds-to-Go.

Now, for a minor SHUDDER...

I don't have the shudder you're talking about (I don't think), but I do have a new vibration/low rumble when there's very little gas-pedal input. Feels like a driveshaft that's out of whack... Not sure. But, I also wonder if IT could be related to motor mounts, too.

I'll be watching this thread, because I think these kinds of shudders are probably all related.

AZSCTACO · Jan 7, 2013

I'm bringing it in for a Transmission Flush tomorrow morning and also describe the issue to my Service Manager to see what they come up with.

---------- Post added at 02:47 PM ---------- Previous post was at 02:45 PM ----------

KMeloney said:
For a minor shutter, check out Blinds-to-Go.

Now, for a minor SHUDDER...

I don't have the shudder you're talking about (I don't think), but I do have a new vibration/low rumble when there's very little gas-pedal input. Feels like a driveshaft that's out of whack... Not sure. But, I also wonder if IT could be related to motor mounts, too.

I'll be watching this thread, because I think these kinds of shudders are probably all related.

Is the rumble that your having at low speeds? Mine feels like a rumble as well come to think of it.

Modded · Jan 7, 2013

AZSCTACO said:
Thanks for the suggestion. I was reading some other threads and read that someone was having harsh/delayed 2-1 shifts while stopping.....I think that's what mine is doing as well. Could a bad motor mount cause that?

I do not think the engine mount would cause delay shifts. It may make shifts more pronounce though. Best way to check it is have rev the engine from under the hood and see how far the engine comes up (if it does at all).
Even though you mentioned it not being the rotors, I just changed my warped stock rotors at 36k miles a week and a half ago. Before changing them, I would get a shudder/chugging feel when slowing down from 25MPH to a stop. I could not feel it it until I got below 25MPH.

AZSCTACO · Jan 7, 2013

Modded said:
I do not think the engine mount would cause delay shifts. It may make shifts more pronounce though. Best way to check it is have rev the engine from under the hood and see how far the engine comes up (if it does at all).
Even though you mentioned it not being the rotors, I just changed my warped stock rotors at 36k miles a week and a half ago. Before changing them, I would get a shudder/chugging feel when slowing down from 25MPH to a stop. I could not feel it it until I got below 25MPH.

Thanks for the suggestion but I changed out all my rotors and pads and they aren't warped. It's weird that it happens more when it's cold out.

KMeloney · Jan 8, 2013

Alex -- I've had my trans "flushed" at the dealership, and despite them telling me how much junk was flushed out, it didn't make anything better. These trans are bad, imo.

As for the motor mounts, please keep me posted on that. Thanks.

Goodinblack · Jan 8, 2013

I am not a fan of "flushes".........

Transmission fluid has a lot of detergents in it. A total flush will introduce almost a 100% new fluid to the transmission.

The new detergent has a tendency to clean too much off the clutch packs.... :imo:

I know a lot of folks get them, and have NO problems with them......even at higher miles........

The shudder could be coming from a failing torque convertor........ you are feeling it disengage.

AZSCTACO · Jan 9, 2013

So I got the Transmission Flush and had the dealership look over the entire vehicle...mounts and all, and they couldn't find one thing wrong with it. Rumble/Shudder is still there in the mornings a little so I guess I'll be waiting for something to bust before I get anything repaired. Truck does run like a champ so I guess a clean bill of health from the dealer was a good thing considering I have 127K on it.

KMeloney · Jan 9, 2013

goodinblack said:
The shudder could be coming from a failing torque convertor........ you are feeling it disengage.

Can you tell me more about this? Aside from a low rumble, I got a "chugging" sensation on deceleration @ 3500-3000 RPMs, like the truck doesn't know which gear to be in. Could that be the torque convertor? And if so, is something like that checked with a scan tool, or is it more of a mechanical (as opposed to an electrical) issue?

Goodinblack · Jan 9, 2013

Well....hard to tell via the internet...........

However, though "mechanical", one could hook up a Tech 2 to the truck and go for a drive.

While driving you could command the convertor to lock and unlock via the scan tool........around the suspected RPM....... and see if it does the described complaint on demand.

My 2009 Suburban sometimes has that chug like feel to it too.......I took it in 2 times for it........they said it was normal..... I have the stock tune and I just live with it.

The Converter going feels more like a jittery shudder.

If a transmission has actual slippage, then usually it sets a DTC code, and raises the line pressure. Increased line pressure results in firmer shifts overall.

KMeloney · Jan 10, 2013

goodinblack said:
Well....hard to tell via the internet...........

However, though "mechanical", one could hook up a Tech 2 to the truck and go for a drive.

While driving you could command the convertor to lock and unlock via the scan tool........around the suspected RPM....... and see if it does the described complaint on demand.

My 2009 Suburban sometimes has that chug like feel to it too.......I took it in 2 times for it........they said it was normal..... I have the stock tune and I just live with it.

The Converter going feels more like a jittery shudder.

If a transmission has actual slippage, then usually it sets a DTC code, and raises the line pressure. Increased line pressure results in firmer shifts overall.

Thanks for the reply, Lee.

Goodinblack · Jan 10, 2013

From my CB Radio.

AZSCTACO · Jan 11, 2013

I have a hypothesis that I wanted to see what all your thoughts are. I noticed this morning when I get the shudder/rumble, the Tahoe is in V4 mode while I'm slowing down....then when I hit that certain speed (around 10-15 mph) and RPMS are around 600....I get the rumble/shudder and then goes away when it switched back to V8 mode. Could this be the issue? Hope that makes sense....

KMeloney · Jan 11, 2013

AZSCTACO said:
I have a hypothesis that I wanted to see what all your thoughts are. I noticed this morning when I get the shudder/rumble, the Tahoe is in V4 mode while I'm slowing down....then when I hit that certain speed (around 10-15 mph) and RPMS are around 600....I get the rumble/shudder and then goes away when it switched back to V8 mode. Could this be the issue? Hope that makes sense....

I need to check how it relates to 4 vs 8 mode, but I'd say that that's the case with me, too. In a previous post, I said that it happens are very slight throttle input. What I was probably experiencing was the input being not enough to kick into 8 cyl mode, and that when it does kick into 8 cyl mode, the rumble/shudder seems to go away. So, your scenario makes sense.

Not sure what it all means, but I think we're experiencing the same thing...

Goodinblack · Jan 11, 2013

Well......on my 2011 Yukon XL........I CAN feel it switch in between modes, and it is rather pronounced.

On my 2009 Suburban, I have to look at the dash to tell if it is in V4. :shrug:

Both trucks are LWB 2WD.

AZSCTACO · Jan 11, 2013

goodinblack said:
Well......on my 2011 Yukon XL........I CAN feel it switch in between modes, and it is rather pronounced.

On my 2009 Suburban, I have to look at the dash to tell if it is in V4.

Both trucks are LWB 2WD.

That's what got me thinking about the V4 to V8 change this morning. I was watching it on the dash and sure enough.......

rickh925 · Dec 21, 2013

I know this is an older thread, but I was given a 2007 Tahoe LTZ from my father-in-law. It had 295K miles on it then and has 306K now. It has developed this same shudder and it is definitely tied to the v4/v8 transition. It shudders while slowing, even if brakes are not being applied, while in V4. When it transitions to V8 around 10mph or so the shudder goes away. While in V4 slowing and the shudder is present, if I bump the gas a little to force it to V8 the shudder goes away. If I put the tranny in neutral while slowing, no shudder at all.

I'm just starting to look for this issue and am a little panicked as we are heading out of town Christmas afternoon for an 800 mile trip.

From past experience with other vehicles, it definitely feels like a torque converter not releasing or something like that.

Has anyone found the definitive answer to this?

Thanks
Rick

AZSCTACO · Dec 26, 2013

rickh925 said:
I know this is an older thread, but I was given a 2007 Tahoe LTZ from my father-in-law. It had 295K miles on it then and has 306K now. It has developed this same shudder and it is definitely tied to the v4/v8 transition. It shudders while slowing, even if brakes are not being applied, while in V4. When it transitions to V8 around 10mph or so the shudder goes away. While in V4 slowing and the shudder is present, if I bump the gas a little to force it to V8 the shudder goes away. If I put the tranny in neutral while slowing, no shudder at all.

I'm just starting to look for this issue and am a little panicked as we are heading out of town Christmas afternoon for an 800 mile trip.

From past experience with other vehicles, it definitely feels like a torque converter not releasing or something like that.

Has anyone found the definitive answer to this?

Thanks
Rick

It definitely has to do with the AFM and changing from V-8 to V-4 mode. Right after I got a BB tune I had the AFM shut off so it stays in V-8 mode all the time and that shudder is completely gone.

Slight shutter......

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