Volvo: idle too high, volvo 940, speed motor

Question
tickover / idle is too high.
handbook states ecu controlled.
easy to adjust ?

my car is volvo 940 se 2.0 turbo estate
1986cc year is 1991.  

Answer
Alan,
Your car has an Constant Idle speed motor(CIS) and that is the part that controls the idle with signals it gets from the LH control unit. A 91 Y/M car you can have the engine codes read. Check for any codes, if clear clean the throttle housing and adjust as needed. If the idle is still not right tap on the CIS motor while it's running and see if that allows the idle to come back down. If it does the CIS motor is sticky and due for a replacment.