WHEN MAKING A COMPLETE STOP, MY RPM GO LOW AND THE CAR VIBRATES LIKE ITS GOING TO TURN OF BUT THEN THE RPM RISES BACK TO NORMAL,AND WEN I HAVE IT IN REVERSE THE RPMS ARE LOW.i also have a noticesable vibration at the steering wheel issue at idle. any ideas? Its a 1994 accord lx AUTO.[X(]

 

the vibration is considered normal for the most part on older cars. i'd inspect the motor mounts though if it feels excessive to you - especially the rear mount.

as far as the low idle goes - start out with a throttle cleaning. just pick up a can of throttle cleaner from autozone and then start up you car. spray the throttle cleaner into the black induction tubing while feathering the throttle to keep the car running. when the can is empty hold the rpm at 2000 rpm for about 15 seconds and go on a road test. how is it?

 

Please, don't shout, we can hear you!

The steering wheel vibration is almost definitely associated with the engine vibrating excessively due to the too low idle speed, as is the general vibration of the whole car. I'm not sure why it wouldidle lower in reverse than in a forward gear(?).

Isthis problem worse if you turn on the air-con, or lights, or wipers, or as you raise / lower the windows? If it is then I bet the IACV is not working properly. The IACV (idle air control valve) is a slave of the ECU and regulates the idle speed whenany auxilliary load is placed on the engine, i.e. it permits an additional controlled amount of air to bypass the throttle body butterfly valve to keep idle rpm at the correct spec. If it malfunctions it may not do this, or it may do it but not fast enough (may explain why it 'goes low but then returns to normal'). The IACV may be faulty, or may just be dirty inside, causing it to stick (or be sticky in it's operation). The IACV itself may be fine, but might have a faulty electrical connection.

The IACV is a rectangularish metal block bolted to the plenum chamber. It's usually fairly easy to find and get at,has at least two small diameter rubber cooling system hoses attached to it, as well as an electrcal connetion with two wires (which may be bundled into one lead). First make sure the electrical connector is properly attached. If that doesn't work then take the IACV off (two bolts, fairly quick and easy) and spray its guts with copious quantities of carburettor cleaner. If that doesn't work then you need to have it checked proffessionally, or just replace it on spec, or its not the problem!

 

I agree with the above posts, however I think some simple stuff should be done prior to adjustment of the idle setpoint of the IACV.

First I'd run the car down to almost no gas. Empty on the gauge meaning about 4 gallons left will be fine. Pour in 2 bottles of fuel injector cleaner and run the car until it cuts off or is as close to empty as you feel comfortable letting it get to (have a full gas can handy). Next, go get gas for the tank. Then, run a half can of Seafoam through the brake booster hose and clean the throttle body well with throttle body cleaner (not carberator cleaner, IDK the differance, but I've heard there is one). Next, after the seafoam has cleared out and any CEL that it may have caused has gone away .... may be 2 days, do a 20 minute engine flush and then an oil change. With the new oil, replace 1 quart with Marvel Mystery Oil. If the problem hasn't improved in 2 weeks, then it's time to start messing with the IACV and idle setpoint.