Howdy Ladies And Gents,

I got a 2001 Honda Civic LX with about 45k on the motor. It hasnt been drivin in about a year and a half and has just been sitting in the garage due to personal reasons. But now to the point, when I start the car the engine runs nice and smooth till it warms up once its warmed up it begins to rev itself to about 2,000 rpm then drop back down to normal idle then rev itself back up. what could be the cause of this? some have told me its an o2 sensor but I need to know for sure. Is there anythinh else it could be? and if so can someone please tell me where the sensors are located ?? any pics or anything that can be helpful lemme know thanks a bunch !

 

make sure its full of coolant. sounds like a problem with the FITV. its the thing on the bottom of the Throttle body with a small coolant hose on either end. if the coolant system is not bled properly it will act like that.

 

vaccum??

 

Check out 7thgencivic.com and see if anybody has had a similar issue. I've got a 7thgen and haven't heard of that yet. Only problem I've had is that sometimes with my remote start the car will crank and won't turn over.

 

bump

 

IACV....could be dirty?

 

FITV, maybe coolant temp sensor. The FITV should close at a certain temp, and if it isn't then the IACV is trying to compensate for too much air going into the engine at idle. The IACV can only compensate for a certain amount, so it can make the idle hunt around like that. The fact that it is doing that once it gets warmed up narrows down the possibilities quite a bit. I agree that it could be air in the coolant lines, but the FITV itself can also go bad. Have you taken it out for a drive to see if it has any other problems?

 

i have taken it out for a drive and nuthing else seem to go bad.... i disconected the FITV sensors all together and it seems to run totally fine... al though it wont let me rev past 3500rpm i also put coolant in bc it had absolutly nuthing in it.... so i belive its just 2 bad sensors that need to be replaced if anyone else has any other ideas lemme know!

 

The FITV isn't a sensor, it's a valve (fast idle thermo valve). What did you disconnect, the coolant lines from it? Give it a little bit to purge itself of air in the coolant system if it was low on coolant, this may clear up on it's own.. What other thing did you disconnect?

 

The iacv goes bad on newer civics quite often u should try replacing it should fix the problem.