idling problem

[tdawg]

have a 1987 bmw 325e idles about 1400 rpm when cold but once it warms up it starts jumping from 700 rpm to 1500 rpm and will not stop doing it if i unplug the temp time switch it quits jumping idle

[Manolito]

You probably have a vacuum leak. If the intake manifold has never been off, it's gasket is likely due. If that is not it, you will likely find the vacuum leak while pulling all the hoses off to get to the intake manifold. The probable reason that it smooths out when you unplug the temperature switch is that the computer goes open loop (rich mixture ) when the you pull that plug.