So I have a 2000 Integra GSR (B18C1) motor in my EF civic.

The engine runs fine and Idles great, However, when I try to hold the RPM at around 2000, the RPM repeatedly drops and comes back up.

Again, other then this minor annoyance, the engine idles and runs excellent.

Here is a link to a video of my car doing this while I'm trying to hold the RPM at 2k.


I'm SURE someone knows what causes this, thanks for looking!

 

vac leak bro.


Take off your intake and cover the throttle body if the engine doesn't die you should be able to hear the leak

 

Awesome, thanks so much for the feedback, I will try to find the leak when I get some free time.

Thanks again!

 

Very common issue with Hondas, and here are the most common causes for idle surging/hunting - vacuum leak, air pocket in coolant system, dirty or malfunctioning IACV or FITV...

How To Clean IACV

How TO Clean FITV

 

My first guess would be a partially clogged cat. Pull the oxygen sensor and see if it still does it.

 

I know it LOOKS like a surging idle, but the idle is fine, never fluctuates. This only happens when I am trying to hold the RPM around 2000. Perhaps the cat could be the culprit, it's been installed for about 8 years now.