Hey guys long time reader 1st time activley posting. pver the past couple of years I have not worked on my own vehicles, but I do have expirence with motorcycles, dirt bikes etc. I have a 91 crxsi with a jdm b20b running all OBD-0 90 ls teg components. Before this swap I had a d16y8 running all 5th gen components and it would vary idle from 300-900 rpms, well a couple drives from AZ to MI I blew it up and installed a JDM b20 and it still does the same thing. The only common component left is the B&M fuel pressure regulator, however the gauge( on the brand new fuel filter ) holds steady pressure. The car drives very well but at idle is extremely annoying. What should I check next , there is no CEL?? I can swap parts, but my diag has something to be desired. Thanks

 

is ur idle high? if it is it might be ur fast idle valve it makes a vacuum leak in order to warm up the car quicker it easy to check first u have the car up to operatin' temp. then remove the intake tube from throttle body next check the the little hole inside throttle body right before ur butterfly flap if u feel suction then its the fast idle valve remember ur car need to be warmed up...

 

Cool I will check that tonight, it seems that the idle may be a little high, however it dips low as well. Its just strange because it has been a common problem with both of the last 2 setups, yet I am using completly diffrent parts , thanks for the reply, if this is the problem I will be soo happy to fix it, the b20 with hasport mounts and a motor with no balance shaft make for a vibrating expirence. While girls may like it I do not .

 

I got the same problem in my EG, and I felt a little suction on the inner hole closest to the butterfly flap after a second or so. Not at first, but when I held my finger over it, it started to create a vacuum. So it is my fast idle valve that's going bad huh?