Hey guys, I'm new on the Forum. I've got a 1997 Accord EX (2 door coupe) that I've owned for almost ten years now. Thus far it has been a pretty loyal dependable car. Any trouble I've had has been becuase of something I caused through neglegence etc (long story there). About two years ago I began noticing that my engine would rev up and down occasionally on its own particulary in cold weather and let me go ahead and mention that I know a little more than the average person about modern auto engines but I am not an experienced tech by far.
Anyway...the problem began getting worse and worse as time wore on until it got to the point that if the car was idling, it would rev way up then down, on its own, as if the computer was seeking the right airflow point for the current conditions. For anyone who has experienced this knows it's loud, frustrating, and embarrasing and attracts unwanted attention (especially from Cops when your sitting at a redlight). I've been asked if my car is possesed. OK all that being said now let me mention that I pulled an identical idle air control valve at a junk yard recently off of a '95 non V-TEC engine. It seemed to solve the problem for about two months but I began getting absolutley awful gas mileage as a result and just this week the original symptoms have come back with a vengence, so im back at square one with a possesed car LOL.

I've checked my check engine trouble codes but they all seem to be in line with the main problem gas mixture too rich, EGR valve etc...Another clue here: When I replaced the idle flow component I noticed my temperature gauge stopped working (the needle just jumps up and down) I think I know whats causing this. While I did bolt down the part properly I did NOT replace the rubber o-rings that were on it, so I suspect the temp gauge was a result of that because the waterflow was being interupted due to lack of pressure etc. So have any of you had any similar dealings??? I feel like I've been kinda on my own with this one. I know alot of you are going to chide me for using old parts and for driving it while the temp gauge is acting up, which I'll admit hasn't been wise. Needless to say I want to solve this for the last time ASAP, but I wanna make sure I'm focusing on the right area. And I'd like to avoid having to buy a new part. The same junk yard now has a few newer wrecked cars closer to my exact year (96-97 repectivley) I'm thinking of trying again with a used part and I already bought some new rubber o-rings designed for that specific idle air control part. Any thoughts???

 

With the idle going up and down + the temp gauge, it sounds like you have air trapped in your cooling system. Did you change the FITV that is under the throttle body (3 bolts) or the IACV that is on the back of the upper intake manifold very close to the firewall and has 2 bolts?

You could have definitely introduced it when you changed the FITV, or you have a leak. So look for a coolant leak under the throttle body where you replaced the FITV.

To remove the air from the system:

With the engine cold, drain all the coolant from the radiator. Replace rubber o-rings on the FITV at this point just to be thorough. Open bleeder valve on the thermostat housing (you will need a 12mm deep socket), start filling the radiator with coolant (use new coolant if due). Air will spit out of that valve as you fill. Keep filling until a steady stream of coolant comes out of the valve. When that happens, close the valve, then top off the radiator. Pull the 7.5 amp backup/radio fuse in the engine bay fuse box. Start your car and allow it to reach operating temp without touching the gas pedal (idle relearn) and see what happens.

At worse, all you really did was replace the coolant.