91 CRX Si swapped in a SOHC ZC now it won’t idle once it’s warmed up

[EricTheCarGuy]

The charcoal canister has nothing to do with it I’m sure so you can tick that off the list. As for the fan motor you need to make sure you don’t have any air in the cooling system, in fact with a Honda idle problem the first thing to check is for air in the cooling system as this will offset just about everything including the cooling fan operation. I was just going to post a link to the video I did on bleeding a cooling system but perhaps the ‘idle speech’ might be more appropriate.
By suggestion I’m going to post my idle speech along with a couple of video links that I hope will help if your having problems with your Honda’s idle. First I’ll give you the link to the Solving Honda Idle Problems video, please remember that adjusting the FITV is the LAST step in the process and you need to back it off at least 1/2 turn after it bottoms out or it will not start properly when cold.http://www.youtube.com/watch?v=L788jKEVblYThe Bleeding a Cooling System Videohttp://www.youtube.com/watch?v=zUp … =relmfuThe video response to the Honda Idle videohttp://www.youtube.com/watch?v=AMj … onseLastly here is the “Idle Speech”There are a lot of things that can contribute to an idle issue, in fact in the end it may still be there to some degree because of the nature of a 4 cylinder engine however here are some things to start with.First start with a good tune up, use NGK or Nippon Denso plugs, don’t change the wires if they are OE, if they aren’t OE you might consider NGK wires as they are very good and less expensive then OE. A quality cap and rotor should be good. A new air filter also helps.Don’t change the PCV valve, if you see an aftermarket PCV valve in there put a Honda in, believe it or not I’ve seen idle issues caused by aftermarket PCV valves, the OE’s last just about forever so you can easily justify the expense.Next a good valve adjustment, this goes a long way to smooth out the idle if done correctly, mess it up and things can get a lot worse though.While you have the valve cover off check the timing belt tension, if you feel a lot of slack this can cause the cam to ‘chunk’ as it spins causing a rough idle. If you think the belt has been on there for some time then you might consider changing it and resetting the tension properly, if it’s not ready for replacement you can reset the tension to take up the slack.DO NOT adjust the idle screw under any circumstances, it is set at the factory and that is the reason it was sealed in the first place. If you find that the seal has been broken and you have a low idle and you have done all of the above then you might turn the screw out a little to see if that helps the idle but only enough to try and bring it back to where it was before it was adjusted in the first place.Last clean the screen in the Idle Air Control valve, this can get clogged up with carbon over time and cause the flow through it to be restricted which can cause idle issues.If you still have a ‘rough’ idle after all of this THEN look to the engine mounts as you want to be sure the engine is running correctly before you go for those as the one in the back is a real pain to replace.I hope this info is helpful as I get a TON of questions about Honda idle problems, thanks for reading.