2004 Acura TL with Navi, AT. 218000 miles. Upon acceleration there is a vibration or shuddering which seems to have gotten worse as the car has gotten older. It seems to be in the drive train. Most noticable if going up a slight incline, in 3rd gear and maintaining about 1800-2000 rpm. Not noticed on hard acceleration or highway speeds. Not the tires which have been replaced twice. Noticed this when the car was new, but wasn’t as prominent nor as consitantly duplicated.
My first suggestion is to check engine and transmission mounts.
Has anyone checked the wheels for possible out of round?
Believe it or not, that’s common for that year TL. They fixed it in later years of that generation, but in many cases there is no complete fix for the '04. Some steps to take to reduce the vibrations:
First, when’s the last time you had the tranny fluid flushed? While you’re at it, replace the 3rd and 4th gear pressure switches as they have a tendency to fail in that transmission, which then kills the transmission in short order.
Second, this TSB might apply to you, even though it’s for a 5th gear vibration. The TSB refers to the same general RPM range as you, and going up hill:
Also note that these cars are extraordinarily sensitive to flat-spotting and wheel balance, so if you’re not getting top-of-the-line tires or not having them balanced on a Hunter road force machine, you can get vibrations which will be more noticeable at certain rpms/speeds than others.
Since you noticed it when it was new, I suspect installing that damper might help.
I was not allowed to see the TSB at http://tec…05-017.PDF and would love to know more about “that damper.” I have had this exact same problem on this model and year as well, starting 120,000 miles.
From the TSB:
""5th Gear Vibration or Drone"
Applies to : 2004 TL with A/T
“Symptom: A vibration is felt or a drone is heard when driving in 5th gear between 50 and 60 mph at about 1500 rpm. The vibration may be more pronounced while accelerating up a slight incline”
The Service Bulletin Corrective Action is to install a dynamic damper onto the bottom of the front subframe near the rear engine mount."
Now again, this is a 3rd gear vibration we’re talking about and so it may not be that - it could be that the tranny was starting to die. The '04-06 automatic transmissions were notorious for having bad pressure switches which caused the premature failure of the entire transmission.