Evo 8 crazy idle

Hi guys, I’m having some issues with my evo 8. The idle is very very inconsistent, I’ve done the setup just as the manual tells me how, and it works fine one day and the next is crappy. I’ve changed the iacv and nothing same problem and when I’m coming to a stop the car goes crazy to 2500-3000rpms. I did check the idle ignition setup and I think I have it right but I’m no expert. Any tips would be greatly appreciated!

The 4G63 idle stepper is notorious for giving trouble so you need to confirm that the stepper is actually working properly. You also need to let the stepper reset so the ECU knows how open it is. This can be done at key on or key off depending on your settings - By default it should be set to key off but this requires an ECU Power Hold function which you may not have if the ECU is a wire-in. If you set it to reset at key on then you need to turn the car on and wait for a couple of seconds before starting the engine otherwise the stepper may not be reset properly.

You can tell a lot about what's happening with your idle by watching the idle speed data in the run time values screen (press R of F12 to get to this) and then cycling to the Aux Functions tab. In particular the idle status will tell you what the system is doing so you can diagnose your issues and you'll also be able to monitor the idle step position.

Yeah I have ecu hold power, and key off reset, idling now is a bit better but now when I’m coming to a stop Rpms are going up between 1800-2000rpms for a few seconds then they go back down to normal idle

It sounds like your base stepper position table is set incorrectly. Try optimising that before you go much further. You may also benefit from introducing idle ignition control if you're not already using it.

Yes I’m using idle ignition control. I bought the tuning package from you guys so let’s see if I can get it better lol.