I think I figured out when the vibration happens, I can feel it in the steering wheel.. perhaps I'm always looking for things.. but I know this that when I press the brake pedal while the car is in D, a vibration is felt, cyclical.... it doesn't do it in N, or P, transmission fluid level is fine...

I've checked the hose on the brake booster and looks fine, it can slip off fairly easy by hand....
I'm thinking maybe IAC... I know the car been's sitting for a while.... but we've been driving it a lot since September...
mounts look fine etc...

Here is some links where people have had similar issues with other cars:

http://www.rangerovers.net/rrmkiiiremed ... #vibestill

http://www.bimmerfest.com/forums/showth ... p?t=438240

http://www.bimmerfest.com/forums/showth ... p?t=409179

Thanks for any help,
Raj

That hose should be a snug fit,not easily slipped off by hand.
I would suspect a vacuum leak in the connection to the brake booster,or the booster itself.

_________________
2005 GT owner [Non S/C] with a "big DIC".
Two years later and I still love the car.
Thanks Pontiac...Bleen is keen!

sorry Radius kid, I write posts sometimes late.. It looks like it can come off easily.... I'm going to try to check it the next few days... its cold now... is there any way to test the booster? I think in the posts the IAC... could an issue? The vibration happens more when the GP is warm.....

thx

After the car has been driven for a while, pop the hood and try to disconnect the brake booster hose. The system will still be under vacuum and should be very tricky to pull off.
Also, the 04+'s are drive by wire and there is no IAC. The throttle body adapts on its own to maintain idle speed instead of having a separate valve.

_________________

Dubs:00 VW GTI VR6, Low and Slow 91 VW GTI 8v, Shave the Bay!! 91 VW Cabriolet 8v, bitch Basket
GP's:04 GP GT, Past now G-Ma's Girlfriend's 97 GP GT, "Project Pink Power"

There is a way to test the booster,but it involves a vacuum pump/check valve arrangement.
I would just get a small hose clamp from the store and clamp it tight.

_________________
2005 GT owner [Non S/C] with a "big DIC".
Two years later and I still love the car.
Thanks Pontiac...Bleen is keen!

@Matt, thanks for the info, ya I'm thinking of the Olds when it comes to things to look for....

Another thing I've noticed, when I'm waiting at a stop light ,and switch vent modes, I feel vibration too.... like if its related... maybe voltage thing... sometimes I do note the idle moving a little.... not often...

@Radius Kid, Would the Mityvac be any good? I think ours has a seal problem.... I just looked at the service manual... also how do we remove the check valve?

I did see in the service manual bulletin something about a Water pump pulley being off a bit.. but I doubt that would be related to this..

thanks again....

You have a Mityvac too?
That's what you use.
Should be in the manual.

_________________
2005 GT owner [Non S/C] with a "big DIC".
Two years later and I still love the car.
Thanks Pontiac...Bleen is keen!

maybe.,,, but the service manual says a vaccum gauge which makes sense... I'm not sure now though I hope its no the booster
still have to check tommorow

Which vent modes are you switching to? If you switch to any that have the defrost/defog you will notice an idle difference and most likely a vibration because the A/C compressor is turning on.

_________________

GPDIY - For All Your DIY Needs
VS CAM|3.4|HEADERS|FWI|42.5#|HPT|6000k LOWS|8000k FOGS|

@Derek, true for the vent modes... its quite possible..


as for an update, I checked the hose from the booster to the intake, looks fine and is on tight...
I did drive around,shut the car off, then played around with the hoses lol, it looks like the check valve, can come out of the grommet, I wiggled it a bit, and tried but it didn't come out..

I was only to do 3 brake pumps with the car off until the pedal got stiff... it was pretty spongy

I've noticed this vibration only happens when the car is fully warmed up and the rpms around 600...
If the rpms are higher while driving around in D... its okay...

I know in the dealer report, they tested the battery and said the status was medium.. could it be a load issue... like when the rpm is that low just by pressing the brake causes load on the alternator?

Thanks!

It's grasping at straws but it can be argued that when you're stopped (engine running), in drive with your foot on the brake, the RPMs are obviously lower so the alternator is running a bit slower (amperage output is lower than if you are moving down the road) and with your foot on the brake not only is it continually having to provide enough electricity to the vehicle overall but now you're also having to power the stop lamps in the rear. Also, since you mentioned that your battery is "medium" (not really sure what that all entails in your case), the alternator is working to do all this AND try and charge an ailing battery (which alternators aren't designed - output wise - to charge a battery but rather to help maintain the charge).

Like I said this is a bit on the side of "straw-grasping" but I still thought I'd throw it out there. BTW, have the engine and transmission mounts been checked to be in good shape? They can also cause vibrations to be felt (vibration severity can be proportional to the condition of the mount(s)).

_________________


"When you turn your car on, does she return the favor?"

His: 2005 Grand Prix GT2 "Ren" (show) || 1996 Blazer (DD)
Hers: 2005 Grand Prix GT2 "Bleen" (DD)

Does 600 RPM's seem low to anyone else? I've never really been that observant when I had the 04, but to me that number just seems low. I could be wrong though.

_________________

Dubs:00 VW GTI VR6, Low and Slow 91 VW GTI 8v, Shave the Bay!! 91 VW Cabriolet 8v, bitch Basket
GP's:04 GP GT, Past now G-Ma's Girlfriend's 97 GP GT, "Project Pink Power"

Thanks Nathan and Matt...

I'm thinking maybe the battery, the dealer got the car in March, and did tests then, and the battery was tested as 'very average'... hey said they had to clean the terminals...

We got the car a few months ago, and I noticed lots of corrosion on the positive terminal, like the extra goo etc.., I cleaned it off,, and the lights didn't flicker as much....

I've noticed when stopped and turning the wheel, the lights flicker, i guess strain on the drive belt... I'm still stumped about the vibration and brakes..

As for the mounts, I haven't had a chance to check, more like forgot to check 100%... but they they do look okay.. the car does shake sometimes when shutting it off..

thx

Alright so I'm still getting vibrations...
also to note when at a stoplight switching modes on the vent, the same vibrations happen...
idle goes up and down at times...
when I have my foot on the brake, and switch to park, the lights flicker and vibration occurs.. thinking alternator? can it really stress the drive belt?

to add-. when I start the car at times, the engine jumps and its felt in the car...
same as when shutting off...

Hi... I know there hasn't been an answer lately..

but today the vibrations were pretty bad, almost constant at a stop light.
It happens more sometimes, other times not... when the car is warm.

I haven't been able to check the:
dogbones, I think use prybar for play
engine mounts
pulleys/belt (will do soon)
clean TB, maf (I know the dealer changed the filter in march... and I'm guessing the one before was original)
but can the MAF, TB get that dirty in less than 5 years?

Could this be an issue:
http://forum.mazda6club.com/engine-driv ... oster.html
http://townhall-talk.edmunds.com/direct/view/.f0b4e91 (shows maf cleaning helps)

When I set the parking brake, and leave it in D, no foot on brake, no vibration..

edit- forgot to add, that the vibrations start after the car is stopped, for about 5secs.... it gradually gets worse after a few cycles... then stays like that.. vibrating... I did check the valve on teh booster, it felt like it can be pulled off.. with enough force...
Would there be a way to check if there are any leaks... or if it is the brake booster causing this?

One thing to note when we test drove the car, we noticed the brakes where a little squishy.... my dad noticed it.... we have then bled the brakes.... and it seems okay...
The vibration always happens, but the degree of it changes... making me think.. can it be vacuum somewhere... like if the computer tries compensating for something...

I think I get some vibs on start up sometimes... not this cyclical thing, that vibrates throughout the whole car.. feeling it in my hands...
If there was a misfire the light should come on?