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Help with Evo X re-flashing

Practical Reflash Tuning

Discussion and questions related to the course Reflashing


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Hey Guys,

I am re-flashing a 2009 JDM evo x. At first my short term trim was sitting more or less at 0 while the long term idle and cruise trims were around -10% combined.

I removed 10% from my entire MAF scaling and after lots of driving around (it takes forever to update) my long term trims went to less than 1% while the short term trims were +/- 2% fluctuating. At idle though, the long term trims are still less than 1% but the short term trims are constantly positive around 3-6%.

I then set the entire WOT area of my high octane and low octane fuel maps to 11.0 AFR and also switched off lean spool. When I run the car at WOT now the AFR is 1-1.5 AFR points leaner than 11.0 and only tapers to 11.0 near redline.

Can someone point me in a direction on what to do next please? Should I attempt re-scaling the WOT parts of the MAF scaling to bring it closer to the 11.0 whilst leaving the closed loop area with the -10% I took out initially? I have a feeling though that this would lead to me having a choppy MAF curve.

Any HELP would be appreciated.

What Software are you using to reflash

ECU edit

Andre/Chris you guy's feedback on this would be appreciated thanks!

Do you have the Calibration Fuel Map all set to 100%?

Hey yes it's all set to 100%

Apologies chris, I actually replied to this a few days ago but it looks like I took too long and I didn't notice that the forum timed out my reply and didn't post. Let's try this again - I'll combine this reply with what you posted in the other thread too to avoid double ups.

The way you've gone about the tuning isn't necessarily wrong. The EVO X is unique in so much as it uses both a MAF input and MAP input to calculate the instantaneous load value. Then to further complicate matters there is the Calibration Fuel Map table too. This gives you the option to easily make a very large mess of your tuning if you're not careful. What you're going to need to do will depend on the mechanical modifications on the engine as well as the intake system as this will impact the MAF scaling.

Generally if the combined STFTs and LTFTs are within the range of approximately +/- 4-5% I would recommend leaving the MAF scaling alone and correcting any open loop fuelling errors directly in the AFR target maps. If you're seeing errors in closed loop of 10% or more then I'd definitely correct this in the MAF scaling. I'd recommend however making an across the board change to the MAF scaling until your cruise and idle trims are within the range of +/- 4-5% (closer is better but don't beat yourself up too hard) and then make further open loop corrections in the AFR target tables as above. If you start chasing every minute error in the MAF scaling, you're likely to end up with an irregular shape to the MAF calibration which can cause erratic fuelling/ignition and driveability issues.

As Andre say, dont chase small errors, that ECU is capable to correct! 4; 5; 6% (that is in closed loop) Make MAF adjustments smooth.

In open loop fueling, make percentage adjustments, till You are happy with results.

My approach to good fueling is -> set both hi/low octane fuel maps equal. Than make percentage changes in full throttle (each row from 150% to max with good shape). Than If i get full load good fueling as I wish for example 0.8lambda, than i set low octane fueling map a bit richer.

One another thing I have found on evo x - at high rpm's ecu is closing throttle, it is possible to correct that by electric throttle map!