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Good day. I have a few questions.

I am tuning my car. It’s a 2002 Subaru impreza WRX STI JDM. I am using rom raider and ecuflash. Here is where I am at

1. I have a bad front (bank 1 sensor 1) oxygen sensor.

2. With my stock MAF my car idling at about 15 to 23 on my AEM infinity wide band gage

3. I own a 1999 toyota altezza 6speed 4 cylinder and I used that MAF sensor in my Subaru. ( looks and plug up exactly the same) that makes my car idle rich at about 12.5 to 13.8 (it idles up and down.

4. My car shows some knock at idle when I tap the throttle. Does not show any knock under full load and boost about 18PSI. I have removed about 10 degree of timing in the area where knock is showing and it did nothing. So I am assuming its not really knock. I use ecuedit

So the questions are.

Can my bad O2 sensor be causing this, or is it because my O2 and MAF sensor bad?

What do I need to log in ecuedit to tune my car effectively

Does anybody know if I can connect my AEM infinity wide band sensor to the factory ECU and disregard the stock O2 sensors?

Please let me know if I need to send a copy of my rom and also if you need me to do a 3rd gear ramp run (on the road) log and send for your to better assist me. Thanks


Hi Gregory, you'll be pleased to know that we are intending to add a worked example to our reflash course using EcuEdit on a V11 JDM STi in the next couple of months. In the mean time here's some pointers:

First up before you try making tuning changes I'd suggest you get the engine running correctly in stock trim. This means making sure everything is operating correctly such as your MAF and O2 sensors. MAF sensors in particular have a habit of being problematic in Subarus and can cause you to chase your tail withe the tuning. The )2 sensor isn't strictly necessary but the ability to use closed loop control makes everything a lot nicer and provides the ability to correct for any small errors in AFR during normal operation.

Swapping in a different MAF sensor will almost certainly result in a different calibration which you'll need to correct in order to get the AFR to match your targets.

Knock when you tap the throttle at idle is almost certainly not going to be real and I wouldn't get too concerned about it.

Unfortunately you can't connect a wideband up to your factory ECU as it is not designed for this type of O2 sensor.

For the mean time, check out the Toyota 86/Subaru BRZ Ecutek worked example in the reflash course as this ECU is very similar to the operation of a Subaru STi with the exception of the direct injection element.

ok. thanks for the advice.

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