I am having a problem with my Civic idiling eratic then set off the P0505 code. When the car is cold it idles steady around 1100 rpms, but once I hit the accelerator the engine starts the eratic idle then soon after sets the code off. I have noticed that also the engine is at operating temp and I hit the throttle the IAC Valve is still continuing to suck in air, is this normal? I have replaced everything I know that could have been the problem, new IAC valve, ICM, ECU, PCV, Distributor cap & button, Map sensor. I have also check every where around the intake and throttle body for air leaks and found nothing. When the P0505 code is set off the car is very difficult to drive. It sounds like the engine is missing timing at the point, it kicks and bucks till you get past 2500 rpms the the car drives fine.

Please help me figure this one out.

 

Try checking your FITV valve.

Take off your intake so you can see in your throttle body. Start your car and let it get up to operating temp. There is a hole inside of the throttle body. Once the car is at operating temp, put your finger on the hole. There shouldn't be any suction. If there is, you need to fix your FITV.

To fix the FITV, you need to take it apart and screw the plunger back in (really easy).

You should also check for vacuum leaks in your intake system.

 

I have a 1.6 SOHC in my lx model which I understand does'nt have a FITV? I have checked all vacuum lines around the intake with no indication of a leak. A couple of thoughts:

Maybe a leak at the intake manifold?, but it should'nt idle steady when cold.

Maybe a engine coolant temp switch?, but the radiator fan will come on when hot.

Any other suggestions?


Thanks

 

i had the same problem in my civic it ended up being the idle air control valve. it is located on the underside of your throttle body.

 

an addition to my last, ky car was idleing from 1000 rpm to 2000rpm back and forth. and it was the problem i listed before. easy fix. it took 30 min. part is kind of pricy though. the way you can check it is to unplug the sensor that goes into your iacv and the car should idle the same. when you plug it back in if noting changes then its bad. the part was 170.00 at advance auto.