Okay everyone, I'm lost when it comes to this. My 85 camaro is running crappy (similar symptoms everyone else is experiencing lately). I replaced the rotted Vacuum lines from the charcoal canister (and inspected the others), plugs, cap, rotor, and wires. A friend replaced the IAC Valve earlier today and said it was really crudded up. My question is: If your vehicle is not spitting any codes out through the SES Light, and you change the oil and do tune ups regularly, AND add a occasional shot of Fuel injector cleaner how often should the IAC Valve be checked and what else would be the rough idle cause -- O2 sensor???

 

bad o-rings @ the fuel ijectors, or any air leaks behind the intake butterfly.

 

Here's how ya cheat on the vacuum hoses.
GO TO THE GM DEALER.
You want a print out of the PVC system on your 1985 car.
IT WILL SHOW YA where all the hoses go.
ALL plastic lines CAN be PATCHED by using 5/16" windshield wiper hose. ALL THOSE PLASTIC THIN LINES.
NEXT remove the upper intake and have fun inserting a new 1/2" heater hose sized hose at the distributor base, driver side. That is a b!tch to replace, but I had to on my 1985 stuff.
Now, this is after I did the 3.4 swap, I did this recent fix of the hoses, especially the back distributor PCV one.
During my 3.4 swap, I spent a WHOLE DAY patching replacing any suspicious rubber hoses & patching plastic hard lines.
Recently looked at my IAC valve. It was kinda dirty/clean, but, I cleaned it as Tom suggested (carb cleaner, spray down, not into the item, wipe).
You still have a few weak hoses, I'll bet.
FYI, 1985 is a one year, stand alone emission engine hose set up.
AND no parts are available.
Use motor oil, to lube the plastic hoses as you patch onto the hard lines.
AFter I did my final patch (had to remove the upper manifold part for access to back motor hose area), MY IDLE VACUUM WENT FROM 14-15 BACK UP TO 17-18 INCHES OF VACUUM.

 

He replaced the IAC valve? Oops... you just lost $40. You could've cleaned the old one for $3. The cleaner is by the carb/choke cleaners, and it's called "Throttle Body and Intake Cleaner for Fuel Injected Engines" (or something like that). Use it to also clean out your throttle body (instructions on the can).

Car off, unplug the IAC motor. Remove the IAC motor. Remove the hose going to the throttle body. "Head-on" inside the hole where the IAC motor screws into is a small hole. This leads to the front passenger side of the throttle body, and is how air gets "around" the butterfly valve to let your motor idle. Spray the cleaner from the IAC motor hole into the TB. Black crud will ooze out of the passenger side of the throttle body. Spray till the crud stops coming out. Screw the IAC motor back in, put the TB hose back on, plug the connector back in, and see how it goes.

Do your tune-ups include checking the timing?

I've heard a bad CTS (coolant temp sensor, on top of intake manifold, at front of engine, on driver's side) can cause a car to idle funny.

You could change your Oxy sensor, but, you get the bad idle when the car's cold, right? The computer will not look at the oxy sensor until a few things happen, which include the engine running for more than a minute, coolant temp should be above 77 degrees, AND the oxy sensor is above 600 degrees. This puts your computer into "closed loop mode", and it reads the oxy sensor. SO, if you have this idle problem when the car's cold, the oxy sensor isn't being used. However, the CTS is being read. The CTS is one of the things that influences the computer to activate it's cold start injector.

Also, I wonder if your EGR valve is sticking open a little bit.

 

Thanks for the tips. Just to let everyone know, I'll be advancing the timing to about 12 or 13 degrees BTDC tonight. The Vacuum gauge I used (old school style) said I was pulling down 15 instead of the normal 17. I also sprayed down all the vacuum connections to check for a leak. None found. I only lost $25 on the IAC Valve . Hell, at 137K and it being original I figured changing it wouldn't hurt. I am changing the O2 sensor tonight as well (it's probably original too). If all of that doesn't help, I'll get a CTS

 

One other thing I thought of- check your TPS (throttle position sensor) voltage at idle. For our cars, it's 0.55volts +/- 0.05 volts at idle. Other than that little spec, you can use the tech article at thirdgen.org for setting the voltage. You'll need a digital voltmeter for it.