I have a 93 honda civic dx and when my car is first started (cold) the idle is steady but a little high. Once the car warms up it is no longer high but it bounces up and down all the time non stop. It's not the iacv or the fitv nor is it a vaccum leak. I checked with break cleaner for leaks and put on a brand new iacv and cleaned te fitv really good. Could it be a bad wiring harness? Any advice? Thanks

 

Any CEL?

 

No cel ever.

 

Okay you say steady but a little high...it's obvious you think that is not supposed to happen, but it is completely normal. The job of the FITV is to raise the idle so that the car warms up faster. Once the car warms up the idle should be 700-800. If it's not you either have a bad FITV, an FITV that needs to be screwed down, or you have a vacuum leak...which could be the IACV being bad.

You should just go pull an FITV from the junkyard to see if it's bad. If it does the same thing then odds are it's not the FITV. Also, brake cleaner is not exactly designed to be combustible so you shouldn't be using that to check for a vacuum leak, just use carb cleaner or even a fine mist of water from a spray bottle.

 

Yes I know that when the car is cold the ecu is telling it to idle higher and full more gas on it to warm up but it's not like that. The idle is too high. I don't have a tach on that car to give an exact number. That would be nice. Once that car warms up your right it is at a fine idle. I took the fitv out and cleaned it real good and screwed it back in and have tried a bunch of different spots screwing it in to see if I can get the right spot. I still get the bouncing in the idle and depending on where the fitv is the bouncing is either a low idle good idle or high idle. The bouncing never goes away. And I also meant to say carb cleaner not break cleaner haha. The iacv is brand new also and I noticed no changes once I replaced that. That's why I know it's something electrical and not any of those things. I've messed around with all those things a lot because either one of those is usually what the problem is but not on this case I guess. When I unplug the iacv then the car idle still bounces but it bounces really fast and also throws a code so that narrows the iacv out. The fitv is extremely clean now and screwed back into the right spot. I'm lost now haha.

 

Have you tried playing around with the TPS ? unplug it and see if idle steadies out. I had the same problem with my EG. Got it from someone who had rewired it wrong, cause the idle to be pretty sporadic. Sometimes the TPS will cause a CEL but not always.

 

i tried unplugging it and didnt notice a change in the idle at all

 

i also picked up another tps from a junkyard and tried that and still have the same exact problem. I had another ecu for back up and that didnt change anything either when i put that one on. im thinking that its probably the engine wiring harness.