at idle will some times drop the rpms coming close to stalling and then raises the rpms to about 1500. so what could it be.

 

maybe the ecu. Cause my friends hatch did that

 

is it expensive to fix or do u have an idea of what else that could it be

 

My car did that a while back it was the idle control sensor... its behind the intake manifold its two bolts and two coolant hoses so let the car cool down before you take it out.. then check the screen on the sensor they usually get dirty and ashy....if its like that just clean it off and put it back on....my car has been running fine ever since then...oh by the way did it throw a check engine light?

 

no it has no engine light

 

check your Idler Air Control Valve(IACV)

 

alright thanks guys I'll try that tomorrow see if i can get it fixed.

 

i was looking for the idle speed control valve sensor, but the only thing i found was a black box on the throttle body next to the firewall. i couldn't took it off because of the screws it had. i took the throttle body off and cleaned it with carb cleaner,but that didn't help. if i take off that clip that goes to that black box the car idles like it should but i get the check engine code throttle position sensor/circuit A low voltage

 

could some1 help me please! what could it be happening to my civic

 

if the code your getting is TPS most likely your going to need a whole new sensor im not completely sure but thats wut happened to a couple buddies of mine...its hard to take off the tps because i think its riveted on to the intake manifold so yea i dunno wut else to tell you bro hope that helps a lil

 

is your idle at 1500 then it drops then raises back to 1500, if so you need to adjust the idle screw until your idle is at 750, shouldnt take 5 min, thats what was wrong with my old Del Sol.

 

Mine did the same thing when the primary o2 sensor went out. Of course, I also got a CEL at the same time so it was easy to diagnose and fix.

 

Mine does that also were the idles jumps around and i was wondering if somebody could show me were the idle screw is at and how to check if you O2 sensor is bad. I am throwing a CEL PO420 which means: "The PCM has determined that the catalyst system efficiency for bank 1 is below threshold for the current engine operating conditions. (Bank 1 identifies the location of cylinder #1, while bank 2 identifies the cylinder on the opposite bank.)"

P.S. Sorry i don't mean to jack your thread

 

its not the o2 sensor cuz i would get a check engine light. i don't know about the tps but i will check the idle adjusting screw..