Shudder at light throttle

[Meccanoble]

I checked my gaps on spark plugs and was concerned about v4 causing issue this why I got it deleted. Still there...

 

[Lightning 95]

Since you had it tuned out, I would wonder if it really was for sure? I've kind of got used to the V-4 tingle, and probably saving gas whenever I can get it to kick in, when I'm in no hurry to get anywhere.

 

[Vegasmarc21]

Well after driving around for TWO hours around town, here is the result.

1st hour (approximately) no shudder.
Transmission temp was as high as 180 degrees (usually 160ish degrees starts shuddering) was happy....so happy I bought the Lubeguard trans additive, came home and poured it in....

Then I went for a spin.....
2nd hour decided to test in M5 mode to lock out any vibration from v4 mode.
1 shudder....then another shudder 20 mins later.

Tried tow/haul mode off and on with m5 and regular drive mode and as long as tow/haul is on No shudder at all.

So don't know what to think, but I'd say 80 percent better....but now I'm thinking tow/haul advances the timing a little, so if I got a tune(even a canned tune like Hypertech) I could cure this shudder a low rpms....who knows, the shudder could just be detonation from factory timing....

 

[Vegasmarc21]

Does it have cylinder deactivation? Mine does, and I can always feel a light shudder at light load when in goes into V-4 mode.

Yes it has dod/afm cylinder deactivation....

 

[Larryjb]

Well after driving around for TWO hours around town, here is the result.

1st hour (approximately) no shudder.
Transmission temp was as high as 180 degrees (usually 160ish degrees starts shuddering) was happy....so happy I bought the Lubeguard trans additive, came home and poured it in....

Then I went for a spin.....
2nd hour decided to test in M5 mode to lock out any vibration from v4 mode.
1 shudder....then another shudder 20 mins later.

Tried tow/haul mode off and on with m5 and regular drive mode and as long as tow/haul is on No shudder at all.

So don't know what to think, but I'd say 80 percent better....but now I'm thinking tow/haul advances the timing a little, so if I got a tune(even a canned tune like Hypertech) I could cure this shudder a low rpms....who knows, the shudder could just be detonation from factory timing....

This really sounds like the lockup torque converter is slipping. Unless I'm mistaken, the lockup part of the torque converter is disabled in gears 1 and 2. It must be disabled in the tow/haul mode as well.

 

[swathdiver]

With a Tech2 you can see all of this, even how much the converter is slipping. My AFM was seamless, never felt or heard a thing when it turned on and off.

 

[Vegasmarc21]

Dropped off my son at his grandfathers house ( my father in law who is a master mechanic/top dragster racer owns a auto repai shop....loves chevys, even has a chevy bow tie tattoo....he had time to drive my tahoe and he said a lady has a 2013 Tahoe in his shop complaining of the same issue of shudder/vibration when driving low rpm and in gears are higher than 2nd gear....he drove mine tonight and said it is the drive line angle and adding shims to transmission to correct the angle is the only that can be done....he said it's not hurting anything by driving it......he really is a great mechanic, but i saw this video tonight.....and he could be right, but check this video out that when I'm off the gas, my tahoe feels an up and down wobble like the tires are out of round. It could be a separate issue from the driveline, or maybe this is what I'm feeling?

Or check this out....

Part 1

Part 2

 

[Vegasmarc21]

This really sounds like the lockup torque converter is slipping. Unless I'm mistaken, the lockup part of the torque converter is disabled in gears 1 and 2. It must be disabled in the tow/haul mode as well.

When you say "it must be disabled in tow/haul mode" are stating it is disabled in tow/haul mode? Or are you presuming it is disabled in tow/haul mode since I don't get the shudder in tow/haul mode?

 

[Vegasmarc21]

With a Tech2 you can see all of this, even how much the converter is slipping. My AFM was seamless, never felt or heard a thing when it turned on and off.

My v4 is pretty smooth as well, but I was just trying to test in different modes to isolate the shudder.

 

[Larryjb]

When you say "it must be disabled in tow/haul mode" are stating it is disabled in tow/haul mode? Or are you presuming it is disabled in tow/haul mode since I don't get the shudder in tow/haul mode?

I am presuming that the computer disables the lock up feature of the torque converter in the tow haul mode.
An automatic transmission transfers mechanical power from the engine to the gears through a fluid couple. In this mode, the engine will spin faster than the input of the transmission. This gives the engine more power because the engine can rotate faster. To conserve fuel, a lockup solenoid will make a solid couple with the transmission. In this mode, the engine RPM will drop. In order to change gears, the lockup solenoid must release the mechanical lock.

The lockup is not used in gears 1 or 2 because you normally need the power to accelerate. This is why you won't feel shudder in 1 and 2. Presumably, because you need the power for towing, the tow haul mode probably won't use the lock up either.

The shudder you feel in 3 and 4 is the lockup clutch slipping. The Lubeuard is a friction modifier which will affect the slipping of the clutch.