I have a 2003 CL and have been experiencing this problem for more than a year now. During this time, I have tried a few things and performed fixes of other problems (thanks to the wonderful guides in this forum!) which I will list below. When I'm driving between 50 and 55mpg (some times between 50 and 60), the car shakes dramatically, usually during acceleration. I can overcome this by giving the engine more gas. This happens regularly every day and I'm worried I might have a transmission problem. The car now has about 165K miles on it and when it was < 100K, the dealer replaced the transmission under the recall. The transmission fluid is only slightly dark, almost appearing as it did when it was new, and there is no "burnt smell."

I haven't found anyone else on these forums who describe this problem quite the way I am experiencing it so any advice would be greatly appreciated. Thanks!

-Replaced ignition coils
-Replaced fuel pump
-Replaced fuel pump relay (car wouldn't start in the hottest weather)
-Regular oil changes and 93 octane fuel every time

 

Check your motor mounts. Expecially the right one. And buy oem not aftermarket. I was looking into replacing my mounts with some from IP but I read on here that there is a design flaw for the side mount and that a lot of ppl use just the front and rear and still keep oem for the side. Also theres some talk about the IP ones donuting after a while. Hope this helps.

 

I recently had a somewhat similar experience but at lower speeds.

The car would sound like the gears were grinding and/or about to stall if i didn't slam the clutch or give more gas

It turned out my cold air intake had come loose from the throttle body thus not having a tight seal.

straightened it out and it fixed the problem.

 

I will check the vacuum hose. My car has no unusual noises, though.

Concerning the engine mount, I have replaced the right mount to correct a heavy knocking problem. I used an aftermarket product and have noticed that the rubber which provides cushioning has cracked since it was installed about a year ago. I expect to have to replace it again.

During the bucking and shaking, the feeling is definitely caused by interruption of the vehicle's propulsion. Think of the space shuttle on take-off, but not as bad.

Thanks again all!

 

That sounds exactly like the problem I was having with my '01 TL Type S. it was a shudder from 55 to 60. It would immediately stop if I let off the gas or floored it. Before I sold it i did the 3X trans flush and changed all motor and trans mounts. It significantly improved the problem. After that it was only barely detectable. I could not tell the mounts were bad by the visual inspection, but when I pulled them out, they were all in bad shape. I wish i had done it sooner. Hope this helps.

 

Axles are another thought. With those high miles they are past their lifespan.

 

There's also 'Engine Mount Control System' to check. Procedure starts on p.4-47 in the Helms service manual.

 

Did u figure it out?

 

What is the life expectancy for axles??? cause I have yet to change mine and I get a vibration only when WOT, so I am assuming the axles are shot.