86 420 sel idle issue
 

I have an idle issue: begin idling around 650 rpm, then over a 10 sec period slowly ramps up to 1000 rpm then instantly drops to 650 and repeats the cycle. Any thoughts on this problem.

Hello franksi welcome to the forum.

It sounds like the idle is set too low. Have a quick check in the owner's hand book - I don't know what it is meant to be. Most engines don't idle that low => 750 - 800 - 850 is more common.

CA Emissions label says 12 degrees btdc @ idle 650 rpm -50 +100, ie 600-750rpm. Any ideas why the loping idle? What causes the cyclic idle speed issue?. Checked and cleaned the idle control valve and it helped slow the idle, as it was sticking, however the cyclic idling remained.

Sorry I can't "help" you any further. I would be checking the condition of tubing though... but wait a few more hours and more people will start to join in. The east coast (USA) breakfast club will be out of bed soon!