so i have a 94 civic and i just recently swapped a d15b but used a skunk 2 manifold. so i keep having this problem wit the IAC ive cleaned it got a new one and still keeps idling up and down.
but when i take off the switch to the sensor(IAC) it idles good..
i was wondering if i can run the car like this or will something get messed up.?

 

Try bleeding the cooling system and also check the resistance of the 2-wire ECT sensor under the distributor. Any CEL codes?

 

it will idle lower i would imagine if you left it unplugged. and of course you'd have a cel for the iacv. have you replaced iacv the seal shaped like an 8? if its old and not sealing it can cause idle fluctuation. i've not personally seen huge jumps attributed to that but if the idle is bouncing about 250rpm or so up and down then it might be that seal. and even if it the seal isn't the whole problem it can't hurt to get a new one.

 

yea code 14 the iac

i check seals are good

 

The fact that unplugging the IACV eliminates the surging idle strongly suggests that the problem is not caused by a vacuum or intake air leak. Opening and closing of the IACV is controlled by signals from the ECU, which in turn uses input signals from other sensors, such as the TPS and ECT sensor. If there is air trapped in the cooling system or the ECT is malfunctioning, then the IACV will behave abnormally, similar to the problem described by the OP.

 

Try what I suggested. If that does not work, then try adjusting the screw on the throttle body:

 

there also could be the fact that you need to set the ecu for the IAC. which requires you to remove the main fuse and the back up fuse to set the ecu correctly. i had the same issue with my 92 and after cleaning the iac i needed to set the ecu for the difference in the intake mani

 

thanks guys, i will check tom when i get a chance and will let you guys knoe how it goes, thanks