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Excessive vibration when idle


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plsmoothy
User

Aug 14, 2008, 12:25 PM

Post #1 of 5 (3448 views)
Excessive vibration when idle Sign In

Hi guys. I have a '98 Mazda 626, 4 cylinder 2.0 with 135,000 miles on it. The engine vibrates excessively when idle. It idles at about 650-750 rpm. It tends to vibrate more when the AC compressor kicks in. I took it into Pep Boys for a diagnostic and they said the car was fine...they didn't receive any codes. Aside from the vibration, the car runs great. Is there any way to fix this? Perhaps increasing the idle speed? Any help is appreciated. Thanks, Paul


way2old
Veteran / Moderator
way2old profile image

Aug 14, 2008, 3:56 PM

Post #2 of 5 (3438 views)
Re: Excessive vibration when idle Sign In

Have you checked the motor mounts?



Being way2old is why I need help from younger minds


plsmoothy
User

Aug 15, 2008, 11:40 AM

Post #3 of 5 (3426 views)
Re: Excessive vibration when idle Sign In

Funny you should mention that W2O. The mechanic who serviced my car said my front right motor mount was broken. I checked it out and it looked fine. How does one determine if a motor mount is broken? Also, there is another odd thing happening in regards to the rough idle problem. I've noticed that when I use my power windows the idle speed drops. Its as if the power necessary to use the windows is robbing the engine of power somehow. In fact sometimes I can feel the idle pulsing just from the turn signal being on. I guess I should tell you at this point that the car has an electrical issue. Whenever I use the hi beams it blows a fuse under the hood. Once the fuse blows, my exterior (headlights, tail lights) and interior (dash, dome) lights work but they are extremely dim. The electrical problem appeared after my sister had some work done on the car many years ago. I simply don't use the hi beams to avoid the issue. Again, any help is greatly appreciated. Thanks ... Paul


way2old
Veteran / Moderator
way2old profile image

Aug 15, 2008, 4:20 PM

Post #4 of 5 (3422 views)
Re: Excessive vibration when idle Sign In

You may want to have the charging system checked. But first you should clean all battery connections. Be sure to include the ground cable connection on the engine. If the alternator is not charging properly, it can cause the rpm fluctuation when a load is applied to the vehicle. Be sure the connections are clean and tight everywhere before you test the charging system. If you have someone in the car and place it in drive (while you stand to the side of the car) and look at the motor. Havr them shift from drive to reverse and see how much the engine rocks. Also have them accelerate a little while holding the brake with the parking brake engaged also. Be sure the car does not move, just torque the engine to flex the mounts.



Being way2old is why I need help from younger minds


plsmoothy
User

Aug 15, 2008, 8:04 PM

Post #5 of 5 (3414 views)
Re: Excessive vibration when idle Sign In

Copy that. I'll check it out. Thanks again Way2old.

Paul






 
 
 






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