alright i have a 99 jdm gsr in my 99 ex. i just got a valve job done on it and new cam gears. i put everything back together and started it up and it ran fine for a second but then the idle started jumping from like 2600 down to 1000 rpms constantly and after it got warm it was still doing it. i dunno whats wrong with it. posibilities in my head are that its either something to do with the vacum hoses from the fuel pressure regulator or there is a sensor that isnt pluged ing on the right side of my intake manifold and i think it should be plugged in under there somewhere but i cant find it...... if you have any other ideas i would appreciate it im ready to get this lil hot rod back on the streets!

 

iacv? Mine did the same thing and that's what was wrong with mine. The plunger inside was stuck.

 

Since we're talking hybrid powertrains, there is a chance that this is wiring related.

Moved to Engine Tech & Tuning.

 

im pretty sure that the iacv was replaced recently and the switch on the inside is moving fine but ill prolly try a new one see if that helps thanks

 

Which ecu are u using? The civic pin outs may not be in the same locations check the wiring with the ecu you are using.

 

check you vacuum system... My buddy had a smiliar problem, he had a slight vacuum leak around the brake booster (the big circular thing on the driver side of the firewall), although his car was built from a junkyard rolling chassis...

However, did you do the swap yourself? Or if someone else did it, maybe they "bumped" the brake booster and it lost it's vacuum seal...

Check it out...