Bad vibration 2002 Honda Accord 86,000 miles

My car vibrates really bad when stopped and in drive. It does not vibrate in park or neutral. I took the car into my local mechanic who replaced the spark plugs, idle air control valve, throttle body gasket, charged me $412.55 and it actually runs worse. The mechanic assigned to my car said he couldn’t feel it so just replaced what he thought might be causing this vibration. It took me a day to calm down and take the car back and speak to the manager of the department who was amazed at how bad the car vibrated. However, they have no idea what is wrong and didn’t offer me a refund. Any thoughts?

Pending more info, that “mechanic” should not be allowed to touch your car. He claims to not detect a problem and just randomly replaced parts on a whim? You might want to try a new shop.

Is the check engine light on? Do you know if the “mechanic” did any kind of diagnostic work?

How many miles are on the car? What do you typically do in terms of maintenance other than oil changes? Just oil changes? Or follow all of the recommendations in the manual?

Vibration at idle is very generic and can come from a lot of different things. Is there a tachometer on the car and, if so, what are the RPMs when it’s vibrating?

In addition to the good advice from cigroller, I want to add that the OP should have the motor mounts & transmission mounts checked.

In addition to the above, this car should have its valve lash checked and adjusted periodically. If the lash is too great, the engine will be smooth but make a clicking noise. If it is nonexistent, it will run rough but make no noise, and it will soon burn up the valves. Its a silent killer.

If this started after the timing belt was changed, then possibly the balance shaft belt wasn’t timed correctly.

Motor/transmission mounts came to my mind too. Since it happens only when the transmission is engaged.

Same symptoms on my '89 Civic LX. Ran a timing light down the spark plug wires and verified that all cylinders were firing (they were, no ignition problems). Pulled the plugs: #3 was wet. Did a compression check: 150psi on #1, #2 and #4; 30psi on #3. Haven’t taken it apart yet (no garage and its COLD outside!) but I’m going to find a burnt exhaust valve (no pulses coming back thru the intake or out the oil fill hole in the valve cover). As for your car: sure hope I’m wrong!

10 yr old car. Recent tuneup? Has miss in gear. Try plugs? Check. Vacuum leak? Check. Tech watches motor movement while shifting into gear? Maybe. Cylinder balance test? Compression check?

The first step is to verify the problem

If the guy couldn’t verify the problem, he should have at least hooked up the scanner. He could have looked at the fuel trims, misfire monitor, checked for stored fault codes, etc.