It happens often in my 93 accord EX. If I start the car, the rpm fluctuates. If I put the car to drive or reverse, the fluctuation stops.

Another question: When to change spark plug and distributor wires? is there any signs that these should be replaced?

 

anyone with some suggestions please?

 

the most likely cause for the rpm fluctuation is the IAC valve " idle air control valve" located on the back of your throttle body.... also Honda reccomends replaceing spark plugs at 105,000 miles.... as for wires that wouldnt be a bad idea as well.... reason for the iac valve to go bad is a few things.... #1 there is trash .... just debries in the valve... or its getting stuck closed or open.

 

Your car takes standard spark plugs. Change them every 30 thousand miles.

Try pinching the vacuum hose going to the PCV valve when the symptom is present. Putting the car in drive loads the engine due to the torque converter and reduces the symptoms of a vacuum leak.

 

So, I should be changing the idle air control valve and spark plugs. So it has nothing to do with distributor wires, right?
How much is the cost for parts and labor roughly? Are non-honda parts ok? Like getting for advance auto or Napa ?

 

Try cleaning your throttle body/IAC valve. You can get TB/carb cleaner at any auto parts store.

For plugs and wires, I run NGK plugs and NGK wires, but MSD or Taylor wires are good for high performance and racing applications.

 

I read in other online sites that cleaning IAC is a temporary solution and problem comes back. I looked up the price of it in NAPA, AdvanceAUTO and Autozone. it shows around $250. But Autozone showed $78 !!! Why so much variation? is that remanufcatured or something like that?
I could not imagine this thing would so expensive!!

 

if it smooths out after the car is warm it is the fast idle air control valve. take off the throttle body, the FIACV is attached below it (at least i believe so it is on 94+ accords). take off the copper colored cover. screw down the white/tan flux nut. assemble and fixed

 

I have not checked that in details. It starts fluctuating violently at start (exaggeration may be) and I immediately shift to drive in the fear of engine damage or something.
So one more thing to check: IAC or FIAC ??
Is PCV has anything to do with it? I read somewhere else that that can be a factor and in worst can the distributor.

I just named all the parts I guess!!

 

Here is a how-to... https://honda-tech.com/forums/showth...highlight=iacv
I've done it on many cars & it alwas fixxes the loping rpm.