04 V6 shudder/vibration on acceleration.

[talonsaab]

2004 Vue 3.5 V6 AWD with 150k miles/250k kms. Shudder and vibration on acceleration has been getting progressively worse over the last 6 months. It can happen in any gear and doesn't matter if it’s normal or hard acceleration. When cruising at steady speed or coasting it is not noticeable. The worse case is when it's in a top gear and "lugging" up a hill. It does not seem to be engine related and the tranny has been shifting normally. I change the tranny fluid about once a year or two. It does not make a difference if the engine is warmed up or not. There is no check engine light. I was thinking engine/tranny mounts or ignition (plugs or coils). I have a laptop engine analyzer, perhaps I should check for misfires and such.

Also, suspension is all new and I can't find any play or issue with the front suspension or drivetrain. Motor mounts are orginal.

Any help is appreciated.

[bluesl2]

Have you had the timing belt changed and valves adjusted? What does the trans. fluid look like, does it smell burnt?

[far2grumpy]

Originally Posted by talonsaab

2004 Vue 3.5 V6 AWD with 150k miles/250k kms. Shudder and vibration on acceleration has been getting progressively worse over the last 6 months. It can happen in any gear and doesn't matter if it’s normal or hard acceleration. When cruising at steady speed or coasting it is not noticeable. The worse case is when it's in a top gear and "lugging" up a hill. It does not seem to be engine related and the tranny has been shifting normally. I change the tranny fluid about once a year or two. It does not make a difference if the engine is warmed up or not. There is no check engine light. I was thinking engine/tranny mounts or ignition (plugs or coils). I have a laptop engine analyzer, perhaps I should check for misfires and such.

Also, suspension is all new and I can't find any play or issue with the front suspension or drivetrain. Motor mounts are orginal.

Any help is appreciated.

The 3.5 PCM is not timid when it comes to setting any misfire codes - so if you've not noticed a CEL I doubt if misfire from any cause is a factor (plugs, coil packs, valves, etc).

It sort of sounds like the torque converter clutch is not happy - could be impending mechanical failure but could also be incorrect ATF or perhaps ATF worn out.

If it were my Vue I'd find a shop that could replace all transmission fluid with engine and transmission operating. I'm not talking a "flush" but more of a operation where old fluid is replaced by new fluid.

This could be pricey as transmission and torque converter holds around 9.5 quarts and you should use ATF-Z1, ATF-DW1 or another highly rated Z1 substitute.

The alternative is to do at least three drain and fills (12 quarts) over several days to get as much clean fluid in transmission as possible.

If fluid don't help - contact a nearby GM dealer to arrange for a PCM update. There is a program to do 05-07 Vue's at no cost to customer but 04 were not included.

[talonsaab]

The tranny fluid looks new,very clean and redish with no burnt smells. It's Mobile 1 semi synthetic multi purpose including the Z1. I went and changed the plugs, air filter and cleaned the TB a bit. It seems to be better but I will have to take it for a much longer drive. As I said before, I change the tranny fluid often and it seems to be shifting fine. I did a bunch of N, P, N, D changes with the brake on and it seems fine. What about worn engine and tranny mounts? Mine are still the original. Thanks.

[far2grumpy]

Originally Posted by talonsaab

The tranny fluid looks new,very clean and redish with no burnt smells. It's Mobile 1 semi synthetic multi purpose including the Z1. I went and changed the plugs, air filter and cleaned the TB a bit. It seems to be better but I will have to take it for a much longer drive. As I said before, I change the tranny fluid often and it seems to be shifting fine. I did a bunch of N, P, N, D changes with the brake on and it seems fine. What about worn engine and tranny mounts? Mine are still the original. Thanks.

Engine and transmission mounts have been known to fail ... they might cause a shudder ... mounts can be inspected by carefully raising engine or transmission with floor jack and big chunks of wood to gt a good look.

Here's general steps from service manual:

Raise engine/transmission/transaxle to relieve tension in the mount.

Observe the mount while raising engine/transmission/transaxle.

Raising the engine/transmission/transaxle removes the weight from the mount.

Replace the mount if it exhibits any of the following conditions:

• The hard rubber surface is covered with heat check cracks.

• The rubber is separated from the outer metal sleeve of the mount.

• The rubber is split through the center of the transmission mount.

• The mount is leaking fluid.

The torque converter is one of most common causes of shudder. See the extract for diagnostic information.

You'll also note a few common engine problems are also mentioned.

[JosephN79]

I wonder if this could have anything to do with the center support bearing? Just a suggestion