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2018 WRX STI emtron plug & play ECU

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Hi I own 2018 WRX STI and I purchased emtron plug and play ECU for my car. I'm learning how to tune stand alone ECU for my own project car (the STI). the car has a built motor but every thing else is stock. The ECU works fine the car starts perfect and warms up fine but once the coolant temps reach 60 and above the engine always idle higher than target idle rpm even on closed loop idle control and fully warmed up. The ECU configured to DBW1 without TMF since I don't have pre throttle pressure sensor. The throttle size is set to 60mm and 0%scaling, I mapped the initial position table, did the DBW calibration, PPS calibration, I kept the throttle area table the same because I tried changing it but not much happened the idle still high I am sure the car is perfect mechanicaly because when I switch to the factory ECU it runs perfect. I'm really lost I hope you could help.


If it's idling high and the closed loop won't bring it down to the target. Then most likely the Initial Position is too high, and you're hitting the Min/Max Deviation clamp.

Are you using both the Idle Speed Control and the Idle Ignition Control? That adds extra variables that makes issues harder to troubleshoot.

I'd say try this:

1. Turn off the closed-loop idle and the turn off the closed-loop ignition idle, so they are both running open loop.

2. Lock idle ignition to your desired ignition advance, probably 15-18degrees (simple way to do this is go to Idle Ignition Control Setup and set 15* to both the Hi and Lo Clamp)

3. Get the engine up to full operating temp

4. Adjust the Initial Position table until the engine is exactly at your target

Repeat 1-3 at various engine temps to build out the Initial Position table so that it works well during warm-up. You can also repeat 1-3 at various target rpm's so that it works even when there's offsets on the idle target.

5. Re-enable closed loop idle controls and remove the Idle Ignition clamps

Yes Im using idle speed and ignition control. I will try these steps thanks.

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