I have a 98 accord 4 cyl vtec with 114k miles. Starts fine, idles fine untill engine warms up and idle drops to around 700rpm, and I start getting a pretty good vibration. Engine runs good at all other rpm ranges, no power loss, and once I get just off idle, the vibration goes away. Problem only occurs at idle at operating temp.

I've changed spark plugs, wires, cap & rotor, and ran some fuel treatment through. Not sure where to go now.

Dirty injectors? Motor mounts? Fuel filter? O2 sensor? Throttle body service??

Any ideas will be greatly appreciated.

 

Air idle control valve probably need some cleaning. Motor mounts possibility. Doesn't hurt to clean the throttle body. Fuel filter replace doesn't hurt either.
Most likely the AICV and mounts, front and rear. Check vacuum leaks.

 

Thanks for th help, I'll check it out

 

I have the same problem with my car honda accord 95 with f23 vtec engine I tried every thing new spark plugs, clean egr, clean throtle body and the AICV. the intake is the original from the car non vtec I even change the distributor, im using a external coil by the way I have checked for leaks I vant find any I dont know what else to do im going crazy pleeass help..

 

Have you try to pull the spark plugs one by one to see if the idle would change? Or pull the injector connectors one by one?

 

Your car idling at 700 isn't a problem. That's completely normal. It should go up ever so slightly as you turn accessories on. For the vibration, that could be the motor mounts.

A cold started car will idle high usually around 1500 or so and get down to 700 or so as the car warms up completely.