what should it act like with the idle air control valve wiring harness un hooked?

i've been having an over heating problem, and a crazy idle that rev's to 2200 and back down to 1000... and back and forth...

last night i changed the thermostat... and bled the air out of the system...

it still idled crazy.... i removed the air filter intake, and when i plug off the side hole in the TB with my finger, it idles fine....


i unplugged the harness to the idle speed control valve... and the idle got a lot lower and it stopped rev'ing up and down... but it still idles at 1300....and lopes to 1400>back to 1300>1400>1300

what should it act like with this wiring harness un hooked?

 

That's exactly how it should be acting, I've been through two of them, and each time they went out or became unhooked rpm's were crazy.

 

if you unplug the IACV then your idle will drop way low and you should get a CEL in the car.

 

it could also be something simple as an intake hose leak or somewhere where air gets sucked in but the hole or opening closes and then reopens and back and forth like you were saying

 

Man... when it idles back and forth like that, it's getting the wrong signal. It sounds to me like you swapped your IAT sensor harness and your IACV harness. They have the same plugs. It causes exactly that, but usually you get a check engine light with a code 14.

Something tells me you've done more maintenance to this car than you're telling us. But if it just started doing all this by itself, I've heard of stranger things happening. I know someone that did the thing I listed above to someone else as a practical joke. Wasn't very funny.

 

well i just realized last night... that my engine light does not come on when i first start the car to let me know it is working... so i very well could be throwing a cel...

is there a way to pull the cel codes with out having the dash light operating?

 

a diagnostic reader.

 

What year car do you have? There's a thread somewhere here about how to check the CEL on 92-95 Civics

 

If this part was bad, would this be a cause of the car not starting?

I have a problem with my 93 coupe and if my car is left for a certain amount of time without having the car started (say for a couple of days) then my car won't start. My friend (I think he flipped a switch) on the valve (which turns on the CEL) but gets the car started. Could this be the problem or something else.

 

Nope. Not on a 92-95. Those cars are OBD-I and rely solely on that light.

Fortunately, changing the light bulb on that car is really easy. Pop the hazzard switch out carefully with a tiny screwdriver, pull the screw out that's behind the switch, pull the 2 screws out of the bezel that are above the gauge cluster, pry gently around the sides of the bezel and it will pop out. 4 screws hold the gauge cluster in, pull those. Disconnect the electrical connections carefully, and you've got it in your hands.

The bulbs are in tiny little plastic holsters on the back of the cluster, and they just screw out with a 1/4 turn. Match it up with a bulb at your local auto parts store and you're good.

The other part is checking the code. Others may have reference to on-line sources, and this topic has been discussed at length many times for OBD-I cars. There's a web page with the codes on it, but I didn't save it. I have a 92 service manual with them in it. But I'll summarize the process.

1. Find the green and red wired test connector on the far passenger side of the car under the dash. You don't need to pull your carpet up to get to it.
2. Cram a paper clip in both sides of the electrical connector so that it terminates that circuit.
3. Turn the key to the on position but don't start the car.
4. Watch the check engine light. It blinks long blinks for 10's followed by short blinks for 1's. It can blink multiple codes, so watch it repeat several times.

example: if it blinks quickly once, pauses, blinks a big blink and then four small blinks, it's telling you a code 1 AND 14. 1 would be a bad o2 sensor, and 14 means your AICV or its electrical circuit is bad. Big blinks are always first.

Sounds to me like you've got plenty to do for now. Ask when you have a question. And have fun. If it scares you, the average shop will bill you about $65/hr to figure it out for you. So have fun.