Problems adjusting idle speed by dealer

[whyaskwhyyxy]

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.

[blazinmiller]

Ask them if they are adjusting the idle when in gear and when not in gear.

When I breifly looked over my manual when I was goingto adjust mine, I could have sworn that in gear and in park are two different adjustments.

I also think they was an adjustment when the AC was on as well.

[accordztech]

i bet the throttle cable is out of wack as well...tell them to check the deflection on it, and if it doesnt look like..adjust it anyways.

dealers dont know shit.

[Hondaman56]

The dealer cannot just up the idle speed. Its a complex process where the computer must be re-programmed. If one just tweeks the throttle adjustment screw the computer will just compensate for it, and place your idle back to where it belongs as per the program which is 500 rpm. The idle is controlled by the IAC which has no adjustment as far as I recall. If you have an excessivley rough idle, they should have at least checked to see if your engine diagnostics is producing an error code and work from there. This diagnostic will cover most of your sensors, emissions, engine controls etc. When my 94 started doing the rough idle thing it was the AC compressor going slowly seizing causing drag on the engine. At 84/K miles you should have had the AC service performed twice to ensure that a failure does not happen. If you have a stick, it could be a flywheel balance problem.