i have a JDM B16A swap I did into my honda del sol. And i'm having the same problem i'm having with the old D15 motor. when the engine gets to a normal operating temprature the RPM start fluctuating between 700 and 2000. I did some reading and found out it was possible my IACV needed to be cleaned. So i cleaned it with no help to the problem. so i'm trying to find some more ideas on what i can look for. the motor currently doesn't have the vtec pressure switch and oil pressure sensor hooked up. but again i don't think that has anythig to do with an idle issue. could it be a possible vacuum line leak?

 

I have the same prob and was told it could be the 02 sensor, if it fouls out it could send the wrong codes to the computer and screw with the idle.

 

well i put a brand new O2 sensor in with the engine swap and i know i wired it up right, or there would have been a CEL if it was wrong. and i believe if ur O2 sensor isn't working properly, it would make the car run ruff but not make the RPMs fluctuate only at operating temps.

 

IAC could be toast. TPS could also be misadjusted. Does the TPS look like it's been removed?

My LS/Vtec was doing the same thing. I cleaned the IAC to no avail. However, I cleaned it thoroughly a second time when it was dead cold and that did it.

 

the throttle body is aftermarket, but i adjusted it myself setting it at .49v at closed throttle and got 4.94 at wide open throttle.

 

Iacv.

 

a vacuum leak could do it - also, look for a temperature sensor problem in the water jacket or reversed water hoses.

 

if it was a vacuum leak though, wouldn't it be a constant high idle, and not one that fluctuaded? i'll check the water temp sensor tomorrow, hopefully that's it, because it would be a lot cheaper then reaplacing the IACV.

 

so i started to dig deeper only to find myself more confused. with a stock throttle body, my car had a FITV but the aftermarket does not have this setup. could this be a cause of problem? the only purpose of an FITV is to keep the idle up while the car is warming up, but the IACV takes over after the FITV closes once the car reaches it's normal operating temp?

 

There is a solenoid operated vacuum valve from the throttle body to the canister - I am not sure what you call if or its exact purpose. It could be faulty. Hope this helps

 

yeah, i think u're talking about the purge valve solenoid. i had the old one break off on the old motor, and i didn't connect it to the new engine. so u may be right. although my new intake manifold doesn't have a place to mount it up. i guess i can jerry rig it up to work and see if it that's the problem. so i guess that coule be something both engines had in common. both have the same fluctuating idle and both don't have the purge valve solenoid connected. i think if that doesn't work, i'll just end up buying a new IACV. : /

 

I keep hearing this same problem from various people locally. I am putting a B16B type R into my 93 Civic ex. The D16Z throttle body has a place to mount the valve. The B16B don't - it must have been on the fire wall or something. I don't even have the valve from the B16B. I hope the old valve works from the D16Z. Was your problem resolved?

 

well i attempted to clean my IACV twice now, and still no luck, but today my new IACV came in, so i'm gonna go pick it up, throw it on and go from there. i'll phone in the verdict when im' done, lol.

 

Figured out mine. Cleaned the IACV twice didn't work, bought a new one at $177 still same prob. Found where my leak was when I leaned onto the intake manifold for support to check a vac line and the manifold sucked me in. The moron before me used silicone to plug a universal hole instead of putting a bolt in there to block it off. The silicone started to peel off and that is where my leak is coming from. CHECK CHECK CHECK all of your lines!!!!!