2004 Mercury Marquis Car Shakes

  • V8
  • 2WD
  • 87,000 MILES
My car started shaking and I have tires that are about 1 year old. I had the tires checked for balance and they did find one tire out of round which they replaced under warranty. The tires are Dunlop Signatures. The car still wobbled after the tires would check so I had a front end alignment done. I still have the wobble at 40-55 mph speeds.

The rotors and brakes were also all replaced, and still wobbles what is wrong who do I beleive or what should I have done to fix?
Do you
have the same problem?
Thursday, October 16th, 2008 AT 9:51 AM

1 Reply

Did you get this resolved? I have two identical 2004 Gran Marquis'. They both have vibrations at about 45-50 MPH. One is worse then the other.

The worse one is a steady shaking feeling at this speed, but it is not a wobble. It feels like the engine is running rough.

My technician has found several cylinders mis-firing. He suspected the individual ignition coils were defective on these cylinders (they showed mis-firing on the scanner tool). He then moved these original coils to other cylinders to make sure the problems followed, and they did. He then replaced these coils with new one. 4 new coils. No further mis-firing observed.

However, the vibration is still there and twice it almost stalled out while stopped at a traffic light. Had to put in in neutral and rev the engine to prevent stalling. My technician then replaced all 8 spark plugs and did a fuel injection cleaning service as a long shot. The vibration still remains but no further stalling has been observed. Too soon to tell however.

The roughness /vibration is a subtle feeling, not extremely pronounced, but still noticable.

I do not believe this issue is resolved.

Any other owners with a 2004 out there who have experienced rough running or a vibration feeling at 45-50 mph? The tires are only 3 months old on both cars.
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Sunday, August 23rd, 2009 AT 11:24 PM

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