I remeber seeing a thread where someone talked about there car shaking while at a stop light and it had to do with a cracked supercharger or something. I have searched everywhere for this Thread. So here is the deal. While at a stop light the car shakes, but it almost feels like your on a bridge of its very very windy outside, but there is no wind and I am not on a bridge. The car sounds like it is idling fine, sounds good, but the car has this weird shake to. Any Idea's? Please Help anyone!

Thank You

 

Thats what my car did when I had a lightened crank pulley on it. But some people have reported a similar issue when their stock crank pulley/harmonic balancer went bad.

 

If it seems to idle smoothly.....

Check your motor mounts for fluid leakage/damage/wear. Also check exhaust hangers to make sure it is not contacting the body structure anywhere.

 

I beleive that I have also lost a little boost and when i go to turn the car off, it acts funny, it dosnt just turn off, its like it stumbles a little before it actually stops! but the car does seem to idle very smooth. So far i need to look at, crank pully, exhaust? If any is familar with the thread that talks about this problem, could you please forward the link to me, I have been searching for an hour trying to find it and have been un suscessful? Thank you

 

If you are indeed experiencing more of a 'swaying' or 'rocking' of the car rather than a vibration or a miss, look for broken motor or exhaust mounts. Open the hood with the engine idling and look for signs of movement. A broken lower engine mount will cause the engine to 'roll' forward and backward. '04 and later cars with the single upper mount have had issues with the damping oil leaking from the mount. Earlier cars have an upper reaction strut above the mount that works similarly to the lower mount.

While looking under the hood, walk back and watch the exhaust tips for swaying movement that would indicate loose of broken exhaust mounts. Look under the car at the exhaust near the engine to see if it's swaying; that's in indication that the front exhaust mount is broken.

If your idle is smooth but the engine speed is oscillating, it could be cause by the supercharger bypass valve fluttering, and can also be caused by a vacuum leak.

 

I have that but didn't think much of it. The way I describe it is if you were sitting on an overpass and a semi drives by making the overpass move a little. It's nothing sudden. It's more of a "did I just feel something" feeling.

I'll take your advice as well, Greatbear. I have to put a better exhaust clamp on my Miltek this weekend so I'll check it out for movement.

I have noticed a slight rpm change, +/- 75 rpm, while idling without the ac on. I don't feel it. Only see it on the tach. Is that what you mean by smooth idle, engine speed is oscillating? If so. Where would one start looking first for a vacuum leak?

 

A miss is unmistakeable, a rapid puff-puff-puff from the exhaust and a fast shaking of the engine. An idle 'surge' is much slower, like someone lightly tapping the accelerator, rhythmically or randomly. The latter happens most often from vacuum leaks or fuel delivery issues. Common MCS vacuum leak areas are the intercooler boots (this also causes a loss of boost), the PCV hose (there is a recall of early models addressing the collapsing and/or leaking of this piece) and the bypass valve diaphragm.

I discovered I need to swap out the stock clamp that came with my Milltek as well, since it seems the pipes have shifted a bit from where I originally aligned them to. The system itself is first-rate, except for the lowball little galvanized clamp that tightens around the slip joint.

 

Tonight was the first change I had to start checking into my car shakes while at a stop light. After check for a vacum leak I jacked the car up and got under there to find!!!! one missing motor mount bolt and one about to fall out and the other 2 we lose as a goose, so the bottom half of the motor just shook. I thightend up the 3 that I had and all was smooth. And I will be letting the dealer know on Monday.. Just thought everyone would like to know what the deal was!! Thanks for all the rely's!!

 

Thanks for the information, schooner2. I replaced my muffler clamp, which btw, Greatbear, the newer Milteks come with a better clamp. I checked everything about the muffler system and all looked normal.

The only thing I could find was that the engine would vibrate more than normal every 15 to 20 seconds for about 2 seconds. I stood there and watched it several minutes and it wasn't caused by a miss, as Greatbear explained, because it seemed to be idling normal.

I'll check out the motor mount bolts and see how they are.

 

Snap.....!! Thats something to check for sure with major vibrations in the car.

 

All seem tight. Top and bottom.

Maybe it's the factory crank pulley going bad so I need to replace it with a light weight pulley.

 

Yellow,

I have just recently started noticing that my car is shaking a bit sometimes when my car is running idle. Sometimes, it runs smooth, but sometimes, i can feel the floor and car shake a little. Not like wind blowing my car. Just like a shaking from I guess the exhaust or engine. I'm getting really paranoid because my gas gauge is broken and I run my cars gas capacity by the miles, and when im close to empty and I feel my car shake and stuff, i get scared. So, I opened my hood, and tried to see anything weird. Sometimes, when I start my car it sounds weird. When I pop open my hood, I tried to hear where the sound is coming from and where the shaking is coming from, but I really don't know. The sound seems to be coming from the left side of the car (When your facing the engine). Also, I noticed a leak around the area I heard the noise from. It is right next to the left horn thing. Does anyone know what is going on. Please help.