2G FIAV question

[98’gst]

I installed a “new” throttle body (oem) on my 2G and since then it’s been better. Except for cold starts. The starting idle is around 2k-2.5k rpms until it eventually settles to around 800 rpms. Other times it’ll start and idle at 800rpm then choke/ die on its own then start up fine the second time. I have checked and already fixed my boost leaks, maf sensor, ect. Is this a symptom of a bad FIAV? I still have my old throttle body and was thinking of swapping the FIAV from that one onto my current one. Just wanted some advice if anyone else had a symptom like that. In case my user doesn’t help, this is on a 98 GST

 

[dwb]

The FIAV can only increase the idle. Sometimes they get stuck open and it's impossible to get it to idle down.
I completely blocked off my FIAV. I live in a cold weather climate and park outside. I have no cold start issues. The ISC is more than enough compensation to keep it running.
You might want to double check that you your TPS is working and adjusted properly, so the ECU knows when it is supposed to idle and let the ISC take control. Also double check that your throttle cable is not too tight and holding the throttle open slightly.

Did you ever get your ISC fixed? https://www.dsmtuners.com/threads/iac-isc-question.549488/ If so, did you set the idle by the book? This is important to make sure the ISC is properly positioned and not over/under extended.

 

[98’gst]

The FIAV can only increase the idle. Sometimes they get stuck open and it's impossible to get it to idle down.
I completely blocked off my FIAV. I live in a cold weather climate and park outside. I have no cold start issues. The ISC is more than enough compensation to keep it running.
You might want to double check that you your TPS is working and adjusted properly, so the ECU knows when it is supposed to idle and let the ISC take control. Also double check that your throttle cable is not too tight and holding the throttle open slightly.

Did you ever get your ISC fixed? https://www.dsmtuners.com/threads/iac-isc-question.549488/ If so, did you set the idle by the book? This is important to make sure the ISC is properly positioned and not over/under extended.

I appreciate the reply. I did get the ISC replaced/ fixed. I just did the usual idle relearn procedure and nothing more. Didn’t ground any pins to relearn the ECU or hook up a laptop. I’ll double check the TPS. The throttle cable isn’t tight and throttle plate looked great when I reinstalled it.

 

[ThunderChild]

If all else is working well, but you have a bad FIAV (stuck open/too far etc) it will idle high but surge. They are technically adjustable, but it's easier to buy a new one, at least it was a couple years ago.