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Running rb25de ECU on rb25det neo?!?!

Fezzifezz
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Fezzifezz Rookie

Fezzifezz

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Posted

Hello guys 

Bough my self an rb25det neo wgnc34 to install on my a31. 

The engine came with an ecu and everything that is needed to get the car running. The engine is bone stock, i only have modified the exhaust, i have a 3 inch pipe all the way to the back with a magna flow muffler at the end. 

When the engine was installed the car ran great for 1 week then i started to notice some problems. Bad idle, loss of power, and sometimes the car will surge and would not let me pass 2.5-3 rpm. 

I changed the maf sensor and added new plugs, that got ride of the surging and the car is now running well, only problem is that its running super rich.

The interesting part starts now. I though my car would need a tune and it should run fine. So i started to look at the ecu and the engine and doing research so i can get my self a compatible aftermarket ECU. 

While doing research i realized the ecu that is currently have on the car belongs to an NA stagea, is that possible?

During the first week the car was getting into boost and i was feeling the turbo and hearing it spool and i can feel the car get into boost, is that possible with an NA ecu?

Could my car be running rich because it has an ECU that is incorrect?

The ecu number is 23713-0v711

 

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https://www.sau.com.au/forums/topic/482403-running-rb25de-ecu-on-rb25det-neo/
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GTSBoy Grand Master

GTSBoy

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11 hours ago, Fezzifezz said:

i can feel the car get into boost, is that possible with an NA ecu?

Why would it not be possible? The ECU does not control whether or not you make boost. The ECU just has maps in it to say how long to open the injectors for each combination of rpm point and airflow meter measured load, and similarly, maps to say when to fire the ignition.

Will those maps be correct for a turbo engine? f**k no. The fuel tables will likely be wrong all over the place. Could well be too rich down low. Almost certainly too lean in the boost regions. The ignition map will have too much advance and you will be at risk of destroying the engine.

All this because the maps in the NA ECU are set up to work with a particular capacity airflow meter and particular size injectors. Your turbo AFM and injectors will both be different to what the ECU assumes and the result (fundamentally rich or lean) will depend on which of the thing (AFM, injectors) is further away from the assumption. Possibly/probably unning lean on boost is a simple effect of NA engines not needing anywhere near as much enrichment near peak torque as turbo engines do, because turbos will ping themselves to death if given lean** mixtures on boost.

**where lean means "not actually lean, just too lean". Truly lean is anything >14.7:1, but in a turbo on boost, lean is anything >12:1, ie still pig rich by NA terms.

Fezzifezz Rookie

Fezzifezz

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@GTSBoy okay makes sense what your saying, but rb25det neo engines have alot of sensors that NA rb25 ECU cant comprehend, like boost pressure sensor, and all the timing sensors, like crank angle ext.. can an NA ECU still make a turbo rb25 run even though im sure these sensor readings are essential for idle let alone high performance. 

Dont forget the car was running amazing for the first week maybe 2. I had no problems what so ever and i was burning tire all the way through 3rd gear.

 

GTSBoy Grand Master

GTSBoy

Posted
Posted

The engine has a boost sensor, but if the NA ECU is not connected to it and can't see any input from it.....what does it matter? The NA ECU will keep just running the engine as if it thinks it is connected to an NA engine.

The CAS is the same.

The AFM has a different calibration, but it's electrically compatible.

As to why it ran well and now it doesn't? See my original reply. You've probably damaged it by doing the wrong thing. Te wrong thing is using the wrong ECU. Too rich. Too lean. They're both bad. You've probably cooked something.

Fezzifezz Rookie

Fezzifezz

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@GTSBoy i see, well i hope the damage is not serious, sine i noticed the symptoms i havent been driving it, only turning it on after messing with it just to see if maybe i solved anything. 

Hope someone can let me know more about the ECU number i shared in my OP tho

Thanks anyway G

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