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2015 WRX DI injection Timing table Question

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Hi Andre can you give me some guidance how to modify Injection timing table on the WRX,

it has SOI Main table and SOI Alternate table (Aggressive Start) not sure which one i have to change.

These tables not are real time so i don't think i can tune each cell and check torque reading on the dyno shown on your webinar,

i am mainly curious if changing them can increase the knock threshold on 93 pump gas.

Attached Files

Joy of OEM software reverse engineering, you don't know exactly what you are changing...

I don't know Subaru DIG strategy but it seems SOI Main table is for "stable/steady" conditions and the alternate for high transient phase.

As written, these table are SOI Before TDC compression , so you can directly change and tune with dyno torque.

Concerning results, do you own tests, but from my experience :

-By changing injection timing you can find torque improvement but it is fine tuning because it is very limited and there are risks of oil dilution and super knock on low rev and also smoke.

-For knock threshold, the DIG itself from PFI permit to retard knock events thanks to cooling effect, but only small timing change will not affect it. And finally you often have to do compromise, for eg retard SOI can improve torque, but if you go too late knock can happen and you will loose the injection timing torque gain by retarding the advance...

Injection timing on DIG is a touchy topic, be careful ;)

Hi Leo thanks for the reply, I just want to make sure I understand you correctly before I go try it out.

Retarding the SOI timing tables will gain torque but more likely to knock and advancing SOI timing tables loose torque but less likely to knock? How should i increase or decrease the tables for example do I increase or decrease entire table by 10 20 to see any effect or i need to increase/decrease entire table 50 100 ?

I didn't give you trend, only example, because depending on your engine design and current calibration you can find different behavior.

Study how DIG works before changing value : Injection can be done from "beginning" of intake phase to "end" of compression phase.

So by 100°CA from BTDC compression you will be quickly over this range...

I recommend 10°CA from you current setting even if this will affect lightly the results. You can try 20°CA to clearly draw some trends.

But my last recommend is to don't play too much with this parameter only if you are really doing "engine development", I think it is not needed to achieve a higher power level.

Got it thanks

That table looks quite similar to what they use in the FA20 FRS engine (probably no huge surprise). I just had a quick look at the table I'm using in our car and the stock DI timing for the FRS is a lot more advanced, particularly at low rpm. I'm around 300-320 deg at low rpm and 375 deg at high rpm/load.

I would simply approach this map by making a small change and testing the result. I'd suggest a change of 20 degrees at a time as this should be enough to guide you in the right direction.

Can I make both SOI Main table and SOI Alternate table the same?

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