So I’ve been dealing with a bouncing idle (about 700-1000 rpms) on my 1994 integra LS. To be more specific my cold starts are amazing, they start at about 1500 rpms and drop like normal. Once my rpms drop to 1000 rpms that’s when my idle starts actually bouncing. So Im assuming this is an issue that only happens when the car is warm or at operating temp.

I did a quick test after taking it on a 15 minute drive (the cooling fans came on) by taking off the intake pipe from the throttle body. This was to give me access to the two holes for the IACV and the FITV

I started by covering the FITV or the bottom hole to find absolutely zero change in my bouncing idle. Correct me if I’m wrong but I’m pretty sure that means the valve is working properly since it’s only supposed to be active when the car is cold. To further back it up, my cold starts are perfect so I think my FITV for the most part is good.

Then I decided to cover the IACV hole or the top hole and the engine immediately sounded quieter but I also heard the bouncing stop. Just to be super sure I turned the car off, unplugged the IACV, then turned the car on and yeah the car was at a chill 650ish rpm and not bouncing. I know idle is supposed to be at 750 (+_50) but it wasn’t too far off.

The IACV in there is brand like I literally bought it 2 days ago but to be fair it’s an autozone duralast part. Really what I’m wondering is if what I’m experiencing is just a faulty IACV since my idle smooths out without it ?


Some other things I checked was my TPS and that was the normal .45-.5 range, adjusted my throttle cable, cleaned the throttle body, and checked my PCV valve.

 

You have learned a lesson: DO NOT buy ANY electrical component for your Honda/Acura from a local/National Chain Auto Parts store... they ALL suck. Buy from your local Honda or Acura Parts Department. You have an ACURA Integra... not an AutoZone Integra.

 

Likely bad IACV based on what you are describing. Get OEM replacement.

 

Most likely it's a vacuum leak, unplug the IACV while engine runs, if the idle continues to surge or goes up you have a vacuum leak, if it drops to about 800 or so then IACV might be bad and stuck open.