erratic idle on 2000 SL1?

[codwall]

I have a 2000 Saturn sedan with a 5 speed and 1.9 liter 8v. The idle revs and drops repeatedly whenever it decides to. Things I have done so far are:
Replaced iac
Replaced tps
Replaced Map
Replaced crank sensor
Replaced ignition control module
Replaced engine
Replaced temp sensor
Replaced fuel injectors and fuel pump
Replaced intake gasket and all vaccum lines
Replaced purge valve solenoid
The idle still revs and you can hear the iac open and close pulling air thru the tiny hole inside the bottom of the throttle body...oh i cleaned the throttle body as well. stil the same idle problem. If i unhook the iac it idles at around 500 rpms but drives great. Im losing my mind on this idle problem. So any ideas? the only code it showed was iac voltage circuit low and purge valve solenoid ..

 

[2abuela2]

I had same problem , so I bought ignition control module 2 Times the second time it works perfectly .!!

 

[Derf]

2ab,

That makes no sense. I doubt the source of the problem reported above is the same as the source of the problem you had.

 

[Derf]

That indeed sounds like a purge valve issue where the solenoid was not operating the valve properly and it would allow the vapor to enter the engine at will as opposed to building up to a certain pressure and then releasing in a controlled manner. The rest of the fuel system will try to compensate for the additional fuel being added to the mixture by countering it with additional air. If the purge vapors are entering the engine in a sine wave type manner, the air through the IAT will do the same in response.

Did either of those codes ever go away?

The purge valve itself can go bad internally but you stated you replaced that part. Are you positive that the upper and lower ports are connected to the right lines that lead to other things? It only works properly when connected properly.

The IAC code was likely in response to system requesting huge amounts of air that are Way beyond what should ever be necessary.

Please take a picture of the purge valve. It should be physically attached to the back of the engine ( the side actually, closest to the firewall) and will have two vacuum lines running to / from it. One comes from purge canister, the other leads to the intake manifold. I can never remember which is which but if you provide pictures of which is going where, I will go out and pop the hood on my 95 to confirm or deny.