Why does my RPM jump up and down?
 

Hi. So I recently got my first car and noticed as I'm in neutral going down hill the RPM would jump up and down and seems to stop as I'm braking and stop. What should I do? Oh I forgot to mention I have a 93 Civic HB VX D15Z1.

Thanks.

Re: Why does my RPM jump up and down?
 

it sounds like an IACV issue are there any check engine lights??

Re: Why does my RPM jump up and down?
 

yes I had this same problem when at idle on a d16 - it turned out to be the idle air control valve.

Re: Why does my RPM jump up and down?
 

No engine check light.

I'm very new to this so will this be an easy quick fix? What do I need to do to fix my IACV?

Thanks for the quick response.

Re: Why does my RPM jump up and down?
 

If it is the IACV, you can try cleaning it before replacing. Just follow this guide: https://honda-tech.com/forums/showth...+control+valve
Had to do this for my eg.

Re: Why does my RPM jump up and down?
 

IACV most likely, and on rare occasions it could also be the TPS but most likely your IACV needs to be cleaned.

Re: Why does my RPM jump up and down?
 

Does the CEL work?

Re: Why does my RPM jump up and down?
 

This happened to me too. But it was the speed sensor.

Re: Why does my RPM jump up and down?
 

bingo....:thumbup:

Re: Why does my RPM jump up and down?
 

I'll give this a shot today and let you know how it goes. Once I clean the IACV and doesn't seem to do the job, does that mean I need to replace it?

I'm very new to all this, so what is a TPS?

Yea. My wording was a little off to make it sound like the light wasn't working, but would the CEL turn on with my RPM problem?

How'd you know it was your speed sensor?

Re: Why does my RPM jump up and down?
 

Re: Why does my RPM jump up and down?
 

dam same thing is happening to mine.

Re: Why does my RPM jump up and down?
 

Holy balls to the walls it's happening to my 2025 honda gizmo