Hello, I recently just had to replace the short motor in my 02 STi, replace the gaskets and get the heads reconditioned. I ended up upgrading from the ej20 STi motor to the ej25 STI motor. Since I got the car back it's been using quite a bit more fuel and I figured I'd need a retune but will I need a new ecu to run the bigger motor properly? It currently has a Denso ecu, i'm not too sure what model, it has 4K at the top, then underneath 22611AH180, then under that is 112200-2581 12V (I'm guessing that may be a stock ecu?). Will that ecu run it properly or will I need a new ecu? If I need a new one, what would be a good one to get? Another question I have, slightly off-topic but what exactly is flashing an ecu? I'm failry new to this stuff, thanks in advance.

>.< whatever you do don't drive in the slightest bit hard. If you go over 3k rpm or get on boost you are very likely to pop your new motor until you get it tuned.

I think both verso and ecutek should be able to sort you out. Both are reflashes which use your original ECU and just adjust some parameters to suit your modifications. Run a search on both of the above for more info.

Another thing I'd be interested in is how your heads work with the ej257. I thought 2l heads weren't compatible with 2.5l heads. I'm no expert though but worth checking out.

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Twin scroll Pig Bi-Squeeling

Ecutek, or Verso, both of which are reflashes, will be able to retune for your mods.
You shouldn't be driving the car after increasing the capacity without tuning to suit. Or your new engine wont last very long at all. The ECU has no idea that the capacity is different and the Volumetric Efficiency is different. It will be a injecting a quantity of fuel for a 2L engine while your is a 2.5L.
Also, just bolting a 2.5 bottom end up to 2L heads increases the compression ratio.

Surely who ever built your engine should know this and should have told you.
My advice, dont drive the car until it has been tuned.
That is a factory ECU, it can handle it, after tuning.
Reflashing involves, downloading the ECU control data from the EEPROM, making changes to the table with commercial (Ecutek, Verso) or open source (Ecuflash, ROM raider), and then erasing the EEPROM and writing the changed tables to it.
Just like opening a program in your computer, changing it, then saving the changes.
EEPROM stands for Electronically Erasable Programmable Read Only Memory.

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F.B. Racing
01 WRX (STI badged)
2010 XR5 Focus
06 Impreza Hatch 2.0i

Ah ok, thanks guys, I'll do some research into Ecutek and Verso and get it reflashed asap. The people who put the motor in werent 100% sure about retuning it when I asked them :s Oh well, at least they fixed the car, thanks again.

Mr Burns should have given you better advice smithers

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Hahaha

I've tried googling Ecutek and Verso, being pretty new to this stuff I don't really understand the Ecutek site and can't really find all that much on Verso. What are the differences between the two?

Verso only has one dealer - All star garage in malaga. Seeing as you are from Albany, that might such.

Having said that it is unlikely there is a dealer down there for ecutek.

Ecutek will require you to go to a custom tune as their tunes are premade, and I doubt they have one for a 2.5 02 Sti. Will cost more.

Probably better off going a plug and play option like Autronic/Vipec/Etc

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Who is able to tune in the Albany area?

I'd go to them first and ask them what ECU they recommend.

Otherwise you can search on here for ECUTek (MMS and Racetorque) or Verso (Allstar).

Given that you are in Albany, if there isn't anyone wanting to tune it, it might be worthwhile contacting someone like Martin Donnon at Willall Racing and seeing if he can provide a suitable tune over email for you to upload and log on the car yourself.

First thing I'd be doing before I go driving around though is finding someone with a dyno locally and getting the AFR's checked. Last thing you want is the new motor to go pop due to the car being untuned for the motor.

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[COLOR="Gray"]550Nm off a 2L... Just wish it was in the dak dak...[/COLOR]

I think the car really needs to go on the dyno, beyond a 'web tune' I would say.

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Its just the internet dude, its not real.
F.B. Racing
01 WRX (STI badged)
2010 XR5 Focus
06 Impreza Hatch 2.0i

^^ Yup.

But if there is no one in town wanting to tune the car, be easier to hire the dyno and use a web tune to check what is going on. Record the logs, send back to tuner etc.

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[COLOR="Gray"]550Nm off a 2L... Just wish it was in the dak dak...[/COLOR]