IAC Valve Or ECM?

[bradvette]

My idle drops and recovers about 10 or so times until it finally achieves a steady idle, after coming to a stop. It doesn't wander, its not high; it simply drops and recovers as I mentioned. Idle is set at 850rpms on the chip.

No vacuum leaks; its steady at 15".
TPS is steady at .53v.
IAC bore is very clean.

IAC was previously replaced, as the counts evidenced by TTS datamaster scan were all over the board, from low teens to over 100 counts when at idle, once warmed up.

The idle condition was perfect for about a month after IAC valve replacement. I went with an Airtex unit and not junk ACDelco.

Now my IAC counts are in the 50's, 60, and low 70's.

Is this new Airtex unit going on the fritz, and that's what's causing the return of the idle drop & recover syndrome? Where should my IAC counts be at idle, in closed loop? Or is my ECM unit (Borg Warner reman unit, installed for 2 years now) bungling up the feedback signal?

 

[bradfordsvettes]

10 to 20 is the standard for iac counts, was a min air rate set on this car ,not sure if this can be done on this car but i think it will apply if not it will hunt also an iac with a pintle that walks out of position will give you problems . if you take the iac out and force the pintle back in , then tap it on a solid surface several times with moderate force the pintle should stay put if it walks out it is bad just my 2 cents Steve