97 volvo 850 GLT. I replaced all my I/C hoses with new silicone ones I had sitting around, Replaced the O ring in the vacuum tree since it was leaking and checked around the engine bay for leaks with carb cleaner. Can't find anything, car runs fine. Cleaned IAC as well as the terminals and connector with electric parts cleaner. The IAC moves freely. When unplugged, the idle goes up a few hundred rpm. Idle sits at about 950 in drive and park. I plan to check resistance on the connector as well as the IAC tomorrow. Seems very strange! Any help? This happened right after my PCV could it be a bad IACV even though it moves freely buy still idles somewhat high

 

IAC still might be bad it it is too loose there has to be some resistance. Id check that first by replacing it with another one

Have you checked the the t-body to make sure the butterfly is closing properly?

Check the t-body linkage and see if your throttle cable moves freely and doesnt have any tight spots

 

The cable and throttle moves freely as well as the plate snapping back well and closes well since I had it off when I did my pcv and checked it. I did notice when shaking the iac the inner piece moves very freely and makes noise. Ill check harness resistance tomorrow along with the resistance on the IACV. I'm going to replace all the vacuum hoses as well tomorrow for good measure. It runs great until the light comes on, then it runs funny. I will try to get ahold of a junkyard one just to test it. Thanks for the help my friend!

 

Today i replaced the one line off of the intake pipe that goes to the evap solenoid i believe and then onto the intake manifold with a bunch of check valves placed in it, as well as the crappy fuel return line and the line from the intake pipe onto the TCV (blue). i reset the codes and also noticed something funny. There was large amounts of green colored corrosion on the MAF and IACV harness connectors. These were two that i kept unplugged for a couple weeks with the car outside (Hood closed of course) while i was doing my PCV since i could not do it in one day and i have another car. Anyway, I cleaned the corrosion off of the terminals and the connectors. Next move is to finish replacing lines and then getting a used IACV to see if that is the problem. I will let you know what happens.. No cel yet, knock on wood. But on drove the car 30 miles or so.