My friend has a '93 dx hatch with a b18b swap from HMO that he bought off a guy locally, it has about 75,xxx miles on it right now. The ecu is the stock ecu for the motor and is chipped by pherable.com but we're not sure exactly what chip it has.
He got the swap in early November of 2010 and it ran fine. A few weeks later it started idling rough only when it was cold. He thought nothing of it and thought that it was just because the motor wasn't warmed up all the way.
Jump to about a month ago. Now it's doing it all the time whether its warmed up or not and whether its cold outside or not. It surges between 750-3800. When he's driving it drives fine when he's accelerating normally but when he goes to slow down, It starts bogging and tries to die and then when he goes to accelerate again it starts to 'hiccup' and sputter until the rpms get back up. There are no CEL's and he's been getting horrible gas mileage since this problem has been more frequent.
We replaced the IAC (used, but clean) and the PCV valve because when we searched, that's what most people recommended that you do. It hasn't helped at all.
Anyone have any suggestions on what we could try to troubleshoot?

 

I found this post ( https://honda-tech.com/forums/showpo...35&postcount=7 ) and tried that and it died when I put my hand over the TB. We let it warm up, then put my finger over the lower hole in the TB and the idle dropped to 750, right where it should be. So now I think we need to clean the fitv. Once we do that, I'll post the results back here and see what it does.

 

Turns out the fitv was the problem. Apparently the previous owner thought that the piece you take out to clean was in all the way, when actually it was half out. We still took it out and cleaned it though and it was actually really clean in there. We put it back in and it worked perfectly.