I am having a problem with my idleling. Car runs great when driving and I get sweet gas mileage but when I stop at a light or something the car will rev up to 1500rpm then drop down to 500rpm then jump back up to 1500 and repeat the cycle over and over again. Its not a fast jump it has a one second difference between changes. I check the fuel pressure guage when this happens and it does not move. What could cause something like this? My friends tell me that every civic they have ever owned did this and no one could tell them why. So I come to you guys. Thanks.

 

sounds like your throttle positioning sensor

 

IACV

 

my last civic idled like that to but it was the tps. and it sucked ***

 

try messing with the idling screw on the throttle body.

 

It could either be the TPS or IACV. Do you have any CELs?

 

Aight sounds logical to be the Throttle postition Sensor. I used to have a Nissan 240zx that did the same thing. But what is an IACV and a CELs? I am not familiar with those terms.

 

IACV = Idle Air Control Valve
CEL = Check Engine Light

You can try and adjust the Idle Adjusting Screw right above the air intake pipe where it connects to the the throttle body. See if that helps.

 

mine was a map sensor

 

sensors suck.
its amazing how shitty your whole car can run because 1 sensor is not running correctly.

welcome to the computer age.

 

I am not getting a check engine light or any codes on the ecu. Would either of these sensors throw a code if it had problems?

 

I believe it could be either the IACV or the FITV = Fast Idle Temp Valve(?)

Remove both and blast it with CARB cleaner. Leave the coolant holes alone.

 

What's truly amazing is that nobody has made the suggestion of a vaccuum leak That's the first thing you should look for when you get an idle like this. It's not your TPS...that's for sure. And don't touch the screw on the throttle body. Check all of your vaccuum lines for leaks. You have no codes so it's nothing electronic.

 

i appreciate all of the help guys i just kinda quit on it's own

 

check your throttle cable...i have had this problem before and it turned out my throttle cable was a bit too tight. So i losened it up a bit and now it idles like a dream :].

 

it turns out that this was the problem. thanx for the help