Hi everyone!

It’s my first time writing in this forum, and im really hoping for some help!

I can’t seem to figure out why my idle on my 1991 Acura Integra RS is bouncing up and down. The car originally came with a B18A1 motor. After that blew I swapped in a B18B1 from a 95 Integra. I didn’t notice the issue immediately, but over the past few months, my idle will fly up to 3000 RPMs and drop back down to 900 over and over again. Bouncing fairly quickly.

The issue seems to chill out after I’ve been driving for about 20 minutes. I’ve cleaned out the IAC valve so I don’t think it’s that. I have done multiple ECU/idle resets.

Just wondering if anyone has ever experienced the same issue. Could it be coolant system related? Possibly a vacuum leak somewhere?

thank you for helping!

 

Have you checked your FITV (Fast Idle Thermo Valve) ???

 

Not yet, just finally found a name for it and it’s idle surge. Found a good YouTube video saying to check that thermo valve. Will try, and report back thank you!