Happy New Year Folks,

I have a '93 NA 940 with Regina and I've had a hunting idle ever since I bought the car in May. It drives fine, just these idling problems.

I popped off the lid of the VDO TPS and there was a good amount of oil in it. Cleaned it up with contact cleaner and reset the TPS. I put a meter on it and got 0 and infinite ohms between the center ground and each outer connector. So far, so good. I have the Mitchell repair CD and it says to apply light pedal pressure (open the switch) and resistance should go to 2000 - 3000 ohms from 0. My reading went from 0 to infinite. The other test Mitchell said to do was to check the WOT contact by depressing pedal to the floor, wide-open contact should close and resistance should go to 0 from infinite. This checked out.

Put the TPS back on the cold car and started. Maybe it was just a quirk but the hunt was gone at the moment. I revved a few times and there seemed to a bump at 1500 rpm when coming down from 3000 rpm. It was hesitating for a split second at 1500 and then dropping to about 800 rpm. As the car was warming up, I revved a few more times and eventually the idle stuck at 1500 rpm and cycled between 1500 and 2000. The only way to bring the car to a 800 RPM idle was to put it in gear.

I checked the error codes and I got a 2-3-3, IACV closed. Now I'm thinking the IACV is the problem. I pulled the plug from the IACV and idled, revved and the 1500 rpm bump was gone. The idle smoothed down nicely from about 3000 rpm. When I put the car in gear, I though it would stall once in awhile but the idle recovered.

All this for one question....Can the idle valve be taken apart? I cleaned it several times with carb cleaner, the piston moves freely and I get 4 ohms between the connections. I plugged it in and it always reverts to the closed position. Am I right in assuming the the computer varies the voltage telling it when to open and close?

Thanks!
Bob