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

I would also check the coolant temp. sensor and clean the air temp sensor, also check for any breaks in the vacuum lines. Last but always overlooked is the warm air intake thermostat. The part is less than 12.00 and I seldom see one working after 120,000 miles.

Try pulling off the throttle body and cleaning the area where throttle plate sets and the two very small holes (journals), one on each side of plate seating position. The PVC dumps oil fumes into air stream just before throttle plate, and film it creates is impressive and a idle killer.

I have the same problem. Please post your findings. Thanks