1998 Honda Civic Vibration at iddle

Hi dstaana,

Thank you for the donation.

Quite often when vibrations are felt at the steering wheels, it indicates bad or out of alignment engine mounts.

Have the engine mounts been checked? Seems the mount might require readjustment or replacement.

However you mentioned that with the A/C off, it is fine, you mean the hesitation and vibration?

What is the idling speed when A/C is on and off?
Do you have the Check Engine Light showing?

Engine mount had been replaced.

Yes. If the A/C is off the engine runs smoothly (no vibration) and it does not hesitate as it runs just fine.

In terms of Iddling speed unfortunately I don't have that meter in my car, its just the tachometer, fuel meter, and engine temparature.

Engine check light never shows on.

If the idling speed is too low, vibrations would occur. Without an in car tachometer, (I believe you only have the speedometer) you would need to get a clip-on gauge to check the idling speed. Try the local parts store, they might be able to assist you on this.

When A/c is turned on, the idling speed should be stable but if the Intake Air Control (IAC) valve air passage is partially clogged, it would restrict some air into the intake manifold and this would cause the idling speed to drop.

Cleaning the throttle body and IAC should help on this.

However low idlng speed would not affect the vehicle performance. Without the AC, engine load is lesser so hesitation might not show and with compressor, additional load would strain the engine.

It could be an intermittent misfiring spark, caused by loose connections, oil in plug hole or bad spark plugs and/or wires.