High surging idle please help

[bmw525iguy]

I am a newbie and have just recently bought my 1992 525i. the car sat unused for almost a year until I bought it. It had ran fine before except would not hold a charge (I replaced the alternator and battery) but now it starts and idles at about 900 rpm then as it warms up the idle rises to about 1300 and then will surge from 1300 to 1600 consistently. The surging will stop if the car is in gear but still at a high idle.
I have read all the idle problem threads and have found and fixed a lot of problems. Like the throttle body boot (large cracks in the folds), large vacuum line from boot to the idle speed control valve (both looked like they had been cracked for a long time), throttle position sensor (coded bad with stomp test, tested good with ohm meter), o2 sensor (tested bad with multimeter, voltage never fluctuated) I took out tested and cleaned the ICV. I can't find any other vac leaks. Please help.

[towball56]

hey man, i've had a terrible time with the idle on my 520i, surging and carrying on to the point where i can't drive it around, i've replaced the air flow meter etc however i have found that it is the idle control valve which is hidden under the manifold, i managed to manually (finger and thumb squeezing pipe)regulate the air from the intake to the valve which immediately began to run properly, so i let go of the pipe and got a long screwdriver and began tapping the valve and suddenly it idled properly on its own, i deduced that it must be the valve sticking inside somewhere, it looks like a real fiddly job to get it out with plenty of kerosene language involved (swearing, cursing etc) and as i have a long weekend coming up i shall devote some time to extracting it out and seeing if it can be fixed or replacing it. the manual says to remove the intake manifold but that will be the last resort as i can reach it and maneuver it around a bit as it is, check that out on yours, good luck- dave

[saab87]

My 1992 525it was surging between 1200 and 1400 rpm. My wife was getting sea sick. I changed alot of sensors with no change. Finally changed the idle control valve. Idle is 700 rpm, and runs smooth as silk.

[saab87]

Figure about two hours to take the manifold off and put back on. If its never been off, get new gaskets.