Iac controller 496 ho & diacom test
 

My 2007 496 ho w/cmi’s is idling quite rough @ nearly 600 rpm
(factory recommended 650 rpms)

After starting at max 30 sec engine always will beep 1 time
Looks for a fraction of a second engine will stall but it doesn’t
Runs all day long without any beeps, you shut it down and restart it, it will beep 1 time

No fault codes with diacom, when beeps occurred you can see in a fraction of a second a screen same as “connection lost with ecm” !

Examined already all electrical connections , found nothing

With diacom test program you can test the iac controller by moving 10 steps up or 10 down
Engine is not reacting, no change in idling speed at all …

Is this normal?

no, idle rpm and whistle sound should change with engine running. engine not running should hear vibration/oscilation sound as you move it up/down.

Ok, thx for this info
I took iac out, was clean inside and not stuck (I can move internal parts slightly)
with ignition "on" I have 12V at wire
but when connecting nothing moves or vibrates
Restarted engine no changes
so I believe the iac is toasted :(
will replace iac and see if better ...