IAC Count? What to do?
It wants to be somewhere in the middle of the range (0 - 310
on an F-body, so maybe 100ish). Seen different numbers from
different people but the really important thing is, it needs to
be far enough from the stops that it has "authority" to drive
the airflow up and down.
There are things that will demand more airflow and more
counts (like a big cam or crappy idle mixture) and there are
things that will make the motor want less air (vacuum leak,
throttle propped open) and there are things that just mess
up the programmed relation between idle airflow and IAC
position as the PCM expects it (epoxy filled IAC port with
too small a remaining air bore).
You are probably somewhat interested in the warmed up idle
but need to also look at the abnormal cases that define the
range; cold start (needs big air and high counts had better
give it) and minimum-load, fully-hot idle (minimum counts,
can you hold down the RPM entirely?).
With a scan tool you want to look at three things - the IAC
count itself, the actual (dynamic) airflow and the desired
airflow. Where the disagreement appears in this "chain" can
lead you to whatever you're chasing.
on an F-body, so maybe 100ish). Seen different numbers from
different people but the really important thing is, it needs to
be far enough from the stops that it has "authority" to drive
the airflow up and down.
There are things that will demand more airflow and more
counts (like a big cam or crappy idle mixture) and there are
things that will make the motor want less air (vacuum leak,
throttle propped open) and there are things that just mess
up the programmed relation between idle airflow and IAC
position as the PCM expects it (epoxy filled IAC port with
too small a remaining air bore).
You are probably somewhat interested in the warmed up idle
but need to also look at the abnormal cases that define the
range; cold start (needs big air and high counts had better
give it) and minimum-load, fully-hot idle (minimum counts,
can you hold down the RPM entirely?).
With a scan tool you want to look at three things - the IAC
count itself, the actual (dynamic) airflow and the desired
airflow. Where the disagreement appears in this "chain" can
lead you to whatever you're chasing.
Log the IAC, if its say 130, open the blade until they drop to your target (I target 40-60). Make sure to reset the TPS everytime you adjust the blade. If you have to open the blade a bunch, check your TPS voltage, if its over .68 volts with the blade closed, then you'll need to enlarge the hole in the blade a bit.
