87 911 wont hold idle

[douglasgoetz]

new to the forum, have an early 87 ( 3 wire iac) and can not get an idle under 1K. customer is wanting the factory 880 rpm. i have verified no air leaks, proper throttle plate setting, good idle switch, throttle not sticking, proper o2 sensor voltage sweep,new iac,

after setting base idle to 880 rpm returns to 1100!!

help!

[908/930]

I think that fuel system is similar to older BMW's where the idle speed is controlled by an electric idle control valve. Make sure the crank speed sensor plugged in and is working properly. Check that the idle control valve is clean and moves freely.