So I encountered the dreaded high idle problem on my Z. I went after the IACV and the AAC. A little tedious but logical. Both checked fine, cleaned them and reinstalled. No change. This was high idle when WARM so when I unplugged the IACV idle would return to normal, plug it in and 1800RPM. After spending half the day doing this based on the FSM and forum fixes, I went to troubleshooting mode. Checked TPS: slightly out at .328V and 3.82V. Reset to factorytolerence of .45V and 4.5V respectively. No Change.
So what powers the IAC? The coolant temp sensor! Unplugged it and saw nothing but green corrosion. Cleaned contacts and plugged it in....instant fix!

I remember from the Bosch L-Jet school: If it's a Bosch component, go back and check something else. Check the coolant sensor first.....DUH!

Often the obvious gets overlooked....

 

hi ,I just fixed my high idle problem 84 ae, the iacv had bad gaskets two replaced both