I have a '95 accord ex 4 cycl. It has 82k. It runs fine except for the "1800 rpm buzz" and a fair amount of vibration in the steering wheel when idling. Most of the time the idle speed is at 500 rpm, and that's when the vibration is most severe. Intermittently the idle speed would stay at 700 rpm and vibration is not so bad. I went to a Honda dealer to have them check the engine mount and bump up the idle speed a bit. They told me that the engine mount was fine and they bumped the ilde speed up to 750. After that, when I stopped at red lights, the speed would drop to 750 for a sec then slowly slip back to 500. I brought the car back to the dealer, they bumped the speed a little more, but then the speed would often oscillate between 1200 and 1500 in "park". However, the speed does stay at 800 when the car is stopped in "D'. The dealer then adjusted the speed down a bit, and now the speed is back to 500 again. Could someone tell me what might be the cause of the difficulty in setting idle speed and what could be done to fix it? Would changing timing belt help? The dealer told me there might be something wrong with some type of internal temperature sensor.
thanks.