: 2005 STS V8 73K vibration at idle



T2daP
07-21-10, 12:09 PM
Hello everyone, newbie to the forum.
For the last week or so I have noticed a vibration when my car is in gear at a complete stop. Kinda feels like the motor is running rough. Check all fluids (ie. oil, coolant, etc) and so far it's nothing obvious. It's still under warranty, but i was hoping someone may be able to offer some help as to was it could be. I would prefer to walk into the dealer and have an idea of what could be going on. Otherwise, you walk into the dealer with the old 'I have no idea whats wrong', and warranty or no warranty they see dollar signs... PLEASE HELP!!!

dash215
07-21-10, 04:06 PM
I had mines in the dealer for the same thing turned out to be bad motor mounts didnt cost me a dime all under warranty.....

EChas3
07-21-10, 08:06 PM
It could be lots of things with 73K. Has it been checked for codes? Ever cleaned the throttle-body? Do you use Top Tier gas? V6 or V8?

D&Ds_STS
07-23-10, 06:33 PM
Ours started running rough, could hear a miss in the exhaust at idle, slight hesitation accelerating from a stop, not as peppy as usual. It eventually set a code and check engine light came on. Bad coil pack, and replaced a spark plug. Been fine ever since.

T2daP
07-26-10, 10:26 AM
I was thinking gas too but i specifically make a conscious effort to put 93 octane in everytime i gas up. But i was thinking gas too because i coincidently loaned the car to my dad while i was out of town, and it was about 4 days or so after i started driving it again was when i noticed it. Never blown out the throttle body since i've had the car. It's a V8 2wd too!

Greg00coupe
07-26-10, 12:08 PM
Top Tier refers to quality of brands no octane. Some claim that all gas is the same but I don't believe that. Unfortunatly event the top tiers are now putting in ethanol.

T2daP
07-26-10, 01:13 PM
I try to go to either BP or Mobil when i can help it... however my dad will just stop at any hole in the wall and get gas which is why i think he may have done just that! What is entailed with cleaning out the throttle body?

KRSTS
07-26-10, 02:01 PM
Doubtful one tank of gas has anything to do with it.

caddyfat1
07-26-10, 05:09 PM
I work near a port area and I see them loading gasoline trucks from Shell, Mobil, Texaco and a few other no-name companies and they pump the same gas from the same tanks only they put them in company marked gasoline trucks and the no-names goes into unmarked trucks. I did notice that they do put different additives in them after filling them but the same gasoline no less.

T2daP
07-27-10, 11:36 AM
One tank of gas can potentially throw quite a few things outta wack. On my previous Cadillac sts before this one, one tank of bad gas cost me almost $500. After further investigation and completely draining the gas tank, the dealer discovered a fair amount of WATER in the tank. So anyway, a couple injectors, idle actuators, and some other stuff later i learned a lesson there. Of course the all pump the same gas (refering to fuel distributors supply multiple brands). So branding nowadays means jack, the only difference is some areas in the fuel is how much WATER are you getting from these greedy gas station owners looking to stretch their profits.
Whew!!! sorry about the tangent guys but i had to get it off my chest. That $500 still hurts after all these years!!! LOL!!! Anyway... taking her in next week... trying to see if the dealer will let me 'borrow' a CTS coupe while they get it worked out...

Angus Young
07-28-10, 11:05 AM
I tell ya I was reading a post on here recently about the intake manifold bolts being loose and lo and behold I checked mine and WOW !!!!!
the bolts actually just sitting in the holes and the others being loose, none of being tight, I have been throwing P420 and P430 codes for quite some time now and it appears that it has been running very lean, I have just went thru and retightened them and hopefully after a tank or 2 these codes go away, I would at least check these as it may be causing your idle issues, mine idled rough occasionally but then cleared for some reason or another, as far as the top tier fuel goes there is a web site http://www.toptiergas.com/ that explaines it in more detail..
hope this helps ....

Jsid7
07-30-10, 12:11 PM
I wouldn't use BP gas. Ethanol ethanol ethanol.

T2daP
07-31-10, 10:46 AM
Okay... by the way the intake bolts on my car are tight.

EChas3
08-07-10, 08:39 PM
Avoid ethanol whenever possible. It pollutes more than gas, is less effecient and is bad for your car. It wouldn't even be available if not for the tax dollar wasting subsidies.

porkfarm
08-08-10, 08:27 AM
I tell ya I was reading a post on here recently about the intake manifold bolts being loose and lo and behold I checked mine and WOW !!!!!
the bolts actually just sitting in the holes and the others being loose, none of being tight, I have been throwing P420 and P430 codes for quite some time now and it appears that it has been running very lean, I have just went thru and retightened them and hopefully after a tank or 2 these codes go away, I would at least check these as it may be causing your idle issues, mine idled rough occasionally but then cleared for some reason or another, as far as the top tier fuel goes there is a web site http://www.toptiergas.com/ that explaines it in more detail..
hope this helps ....

Same boat here... I was doing great on mileage.. 24 MPG avg. After snugging the intake bolts. Best I can do is 19. If the codes do not go away, the cats might be junk, get them checked before 80K.

caddyfat2
08-08-10, 08:52 AM
Same boat here... I was doing great on mileage.. 24 MPG avg. After snugging the intake bolts. Best I can do is 19. If the codes do not go away, the cats might be junk, get them checked before 80K.

Stored codes do not just go away they must be cleared.

sapien
08-09-10, 12:07 AM
another thing to check vibration-wise... the 3-way bracket that holds the belt-driven cooling fan on the front of the engine. the mounting bolts should be tightened to 18 ft-lb

porkfarm
08-09-10, 11:37 AM
Stored codes do not just go away they must be cleared.

They do not go away, but the check engine light will got out if no problems found after some time frame. 6 complete cycles ? Remember even after you clear the codes, you still have to have a full cycle to be in a ready state. Evap system inc. can be a long check if you have a full tank of gas.

I keep my code reader plugged after a cleared code.. I monitor all sensors for some time after.