Mechanics

VIBRATION

2002 Mitsubishi Galant

Shakes or Wobbles problem
2002 Mitsubishi Galant 4 cyl Front Wheel Drive Automatic 240000 miles

I have a strong engine vibration at idle with brake applied(such as at stop light) Have fresh tuneup car runs fine. Have replaced all 4 mounts (2 were bad) Have any idea what is causing the vibration only at stop with brake applied? Thanks in advance. ---Clayton
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Claytonq
November 6, 2010.




Hi claytonq,

What is the idling speed when stopped?

KHLow2008
Nov 7, 2010.
About 800 rpm
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Tiny
Claytonq
Nov 7, 2010.
Recheck the engine mounts, especially the front and rear. The lower support beam tends to get distorted due to impact and this would result in the mounts being compressed and not absorbing vibrations from the engine.

KHLow2008
Nov 7, 2010.
Checked cross member and see no damage have at least 1/2" clearance between it and engine. What about silent shaft? Wouldn't it vibrate at all times if it was out of time?

Tiny
Claytonq
Nov 7, 2010.
The balancer shaft would cause vibrations only at high engine rpm if they are out of time.

Vibrations at idling are usually due to engine mounts of hoses. Use a floor jack to support the oil sump slightly to test if the vibrations lessens or goes away. If engine mounts are non OEM, I would not discount the possibility of them being the cause.

KHLow2008
Nov 7, 2010.
Ok about to pull out what little hair I have left. Have rechecked all mounts, ok as far as can tell, raised engine a little while in gear with brakes set, seemed to get a little worse. Let pressure off. Set idle up 200 rpm. A little better. How about this, before changing mounts and now too have check engine lite. Reading says O2 sensor bad. When in neutral I rev engine and for split second have slight hesitation then all is fine. Would sensor cause poor idle at dead stop? Then be fine as soon as I touch gas. If that isn't it will just live with it. Oh yeah all mounts are supposed to be oem.

Tiny
Claytonq
Nov 7, 2010.
If the O2 sensor is bad, it can affect the idling speed and induce vibrations.

You mentioned that by supporting the oil sump the vibrations increases. That could mean the engine mounts are not synchronised.

Loosen the front and rear engine mount cross bolts and test if it has any effect on the vibrations.

KHLow2008
Nov 8, 2010.

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