Toyoland: Toyota car and truck forums

Most likely you\'re right and he\'s wrong. First thing to do in my opinion is get your computer fault codes read (a lot of places do it for free - AutoZone, I think, among others) to see if the computer sees a problem. Did it always act this way or did you just get it?

Thanks Dave for your reply.  I will take the car to a place to get a computer read out.  The car started with this about six months ago.

Jorge

Need a bit more information - as vibration sources can come from nearly anything.

Did you buy the car new or used?  What kind of service history does the car have?  What has the dealer checked until now?  

Did you notice anything else, other than the ecessive vibration, at the same time six months ago?  Anything added/modified to the car at that time or since then?  When is the vibration most pronounced - at idle and stopped, low speeds, high speeds, coasting, in or out of gear, when applying brakes/slowing down, when accelerating?

Unlikey, but still possible that at least one of the motor mounts is damaged or loose.

Thanks for your advice.  I will provide as many details as I can remember.

I bought the car new.  It has bee in the dealer for all scheduled services religiously.  The dealer says the vibration is normal for a 4 cylinder car.....I do not think so.

In the last six-eight month I installed the xenon bright headlights.  This process required to run an additional ground cable from the battery.  The vibration is most pronounced when it is at idle and stopped.  No issues when acceleration, coasting, or high speed.

Sometime I feel it is an electrical issue.

I also had the fuel injectors cleaned by the dealer with new plugs, and high qualify air filter.

Again, thanks for the advice.

Possible that it could be an electrical issue - one quick way to test it is to turn on the A/C or defrost setting, when you experience the shaky idle and see if it improves the idle quality (idle speed should should speed up).  If the shaking is less pronounced or completely gone - it is possible the xenon lamp upgrade has created a ground loop and/or introducing too much electrical noise in the system.  The fuel injection system is particularly sensitive to electrical noise.

Could be the IAC valve is clogged or gummed up as well - it is inside the throttle body.  If this is clogged, the engine will not be able to bypass air through the valve - your idle speed will be erratic and you might experience some vibration.  This will only be apparent at idle speeds or at a stop - since your foot is off the accelerator - the throttle plate is closed.  Might just need a good throttlebody cleaning.

Don\'t know if you got this fixed, but this is my two cents.

My 04 Corolla seemed to have a mild rough idle.  I\'ve had it since new, and it had gradually developed it (probably around 35-40k miles.)  While I felt like it wasn\'t hurting anything it just seemed a little irritating.  Like the previous posters mentioned idling with A/C on helped because the rpm\'s where higher.  

On my 04 it still has a throttle cable and an adjustment screw for idle speed.  I simply bumped that up a tad (idles now around 700-800 rpms.)  That helped smooth out most of the issues...  I don\'t know if the 06\'s are drive by wire or still have a throttle cable (or if there is an adjustment screw for the drive by wire), but it\'s something to look into (assuming a little higher rpm would help.)

I certainly see how the IAC could effect idle thought, and it is/was a good place to start.
Another idea might be a vacuum test to see if there is a leak.  That would give you a lean mixture at idle and easily create a rough condition.

If you never notice the vibration at other engine speed (especially while driving) then I wouldn\'t be as worried about the soundness of the engine.