My car hunts quite severely around idle (500-1500 rpm) after stopping for a while and then restarting the car when its still warm. It only happens in this condition.

No issues on cold starts or even hot restarts... I've cleaned out the IACV (pretty damn blacked out!) but it didnt help at all. Checked all the vac lines. I'm going to check out the TPS next.

I'm stumped.. Anyone had this issue?

 

What are you using for engine management?

 

Sounds like a tuning issue. I had a hunting idle with my first crappy tune (not from Automotion, someone else).

 

My guess is that your idle speed is set too low. When the minimum idle threshold is too low the AEM will respond by picking rev's up dramatically to keep from stalling. That causes the hunting cycle. Raise the lower threshold from 500 rpm to 800 rpm and that should help smooth out your idle.

 

I'm using AEM EMS. I don't think its the tune as it was fine when it was tuned. Only started to happen a few weeks later..

When its running ok, it usually idles around 1000rpm.

and one other thing, I have a serial gauge with O2 readout and it shows full lean (18+), when the hunting happens.

 

I think it is the tune. It only happens when the car heats up quite a bit, right? Like after a hard drive or in the summer? It's the tune. There's a temp compensation map that adjusts the tune for such conditions. Simply up the lower idle threshold and you'll smooth out the idle.

I have trouble shot this before on the S2000 and on a Supra. It's likely the tune or something like a bad PCV...less likely.

 

It's the tune.

 

OK I'm a little hesitant when it comes to making changes to the map. Where can I find this option in the EMS and which parameter do I change?

 

Open AEM Pro, at the top you'll see a bunch of menus for things like setup, ignition, fuel, etc... Go to the on that say 'Idle.' In there you should see a place to go to Idle Parameters...I cannot remember off the top of my head but I think it's in the advanced options sub menu. Go there and change the lower idle threshold value to something around 800 or 1000rpm. Voila!

 

Hmm I checked all the available parameters and there isn't one that says Lower Idle Threshold.

The only nearest thing I can see is:

Under Options - Idle
Idle FB Above rpm = 400 rpm
Idle FB Below rpm = 1700 rpm

Is this the setting?