I got this car in June of last year. The very first day I drove it home from the shop, there was a brief vibration as I was coasting down the road. It was so brief that I didn't have time to check any gauges to see what the conditions of it were. It stopped and didn't happen again for a long time, so I didn't give it much thought.

Within the past 8 months, this issue has been recurring much more intermittently and has been getting worse. I have now determined that it only happens when the engine is hovering at 2500rpms and driving at around 30-35 mph. It only happens when speed is constant and there is no accelleration or deceleration. If I let go of the gas pedal or press it to accellerate, the vibration stops.

When I say "vibration," I suppose the definition differs. When it first started, it felt like running over those grooves on the side of the highway (that are meant to tell you that you're driving over the white lines) at a low speed. Now, whenever it happens, the entire car shakes like I threw two rods or something (with no loss of power).

I've heard a heat shield vibration before. My old 92 EX had a really loose shield that I never felt like tightening, so I would recognize the sound. This is something much different, and much stronger. You can feel the shaking through the steering wheel.

Any guesses?

 

First thing that comes to mind is that one or more of your wheels have gone out of balance. Also carefully inspect each tire for obvious defects (bulges, puncture with foreign object, etc.).

 

The tires are brand new, only 800 miles on them, full set. I had everything aligned and balanced when I got the tires. It was doing this before, and it's still doing it after.

 

i had a bad ball joint and it only vibrated at certain speeds. I think civicexracer told me that the frequency at which the wheels were rotating was just right as certain speed so that the vibration couldn't be felt at certain speeds, and at other speed it was REALLY bad. Hard to explain, btu that might be what it was....either that or a bent rim possibly? That seems to do the same thing. And a ball joint would get worse over time, such as our 8 months

 

I had a somewhat similar problem - vibration at ~60-65 mph before and after tires replaced and wheels balanced. Returned car to NTB TWICE for wheel re-balancing but problem persisted. Subsequently brought car to local trusted mechanic who fixed vibration problem by PROPERLY balancing my wheels. NTB eventually refunded their charges for wheel balancing and also those from my local mechanic.