legacy ecu interchangable ?

[BDS13driver]

are all ecu of the same year and of the same engine interchangeable with one another ? meaning ? sedan vs wagon ? auto vs manual ? or sedan have to use a sedan ecu ? and auto have to use auto ecu?

[chuckthefuk]

Sedan and Wagon's use the same ECU's

Certain years can not be mixed.

There is no definitive compatibility chart that shows you which ecu will work unfortunately.

Manual (5MT) ecu's will run Auto (4EAT) cars.. However codes will be thrown when the 4EAT tries to communicate with the ECU..
Not sure about the other way around.. I've never tried that.

I've run 96' EJ22E (L) ecu's in 97' EJ25D (GT) and the other way around with great success.
I've tried a 98' EJ25D (GT) ecu in a 97' EJ25D (GT) and it did not fire up .. Not sure what wiring revisions happened in the wiring harness. But that combo did not work.

Interchangeability seems fine up until 98 where evap systems started to change.

A few things to consider.

1) Running a larger engine with a ecu designed for a smaller engine will yield poor fuel maps and different red lines to name a few.
2) Emission controls are different throughout the years.. Some have a charcoal canister front/rear some only front. These issues must be resolved to clear up any P**** codes related to emissions.
3) Running a smaller engine with a ecu designed for a larger engine will yield poor fuel mileage and feel bogged down.

-Chuck

[tnrknght]

Now this has me thinking, because I pulled the phase2 motor from the junkyard, would a 99 legacy ecu work in a early 98 where I originally have a phase1 motor?

[chuckthefuk]

oh hybrid builds.. The 99 and 98 ecu are somewhat the same.. however I can not factually confirm this :-(

Phase II motors need the Phase II intake manifold.. So that being said your ecu still wont fire that motor..

But to add some info to this thread. You can use DOHC wiring for a SOHC swap.. EJ-series motors only have 1 cam sensor so as long as timing is set it should fire up.

-Chuck

[Wiscon_Mark]

Manual (5MT) ecu's will run Auto (4EAT) cars.. However codes will be thrown when the 4EAT tries to communicate with the ECU..
Not sure about the other way around.. I've never tried that.

I've read that an auto ECU won't throw codes if you just plug the TCU back into the harness and leave it be, even though it isn't actually doing anything. Don't know how true that is for all years though.

[tnrknght]

Phase II motors need the Phase II intake manifold.. So that being said your ecu still wont fire that motor..
That being said, Im currently planning to swap the phase1 harness to the phase2 motor with some slight modifications. I know Ill get a cel for the egr since the phase2 manifold doesnt have the egr setup my phase1 has

[chuckthefuk]

I have never swapped over Phase I electronics to a Phase II IM.. TPS/IACV/etc... no idea how that will mount.

[tnrknght]

the iacv connector matches I just have to extend the wires to the other side of the tb, the tps is the same and the only connector I have to modify is the fuel injector plugs. The phase2 coilpack has a 4pin connector, Ill be "using" the phase 1 however its eventually gonna get repinned to the neon connector for the neon msd coil pack upgrade. Other than those the harness wont be an issue.

[r3v_v3ng3]

I have never swapped over Phase I electronics to a Phase II IM.. TPS/IACV/etc... no idea how that will mount.


I did it to my friends legacy. We used his 96 harness on an 01 2.5 rs engine. He was lucky that his car don't have egr so he doesn't have that code but he does have the iacv code since the 01 used a 6 pin iacv. He needs to find a phase 2 throttle body just like tnrknght have that has a 3 pic iacv. I've only seen them on a 99 impreza and sounds like on 2000 legacy too according to tnrknght. After that they all had 6 pin iacv. Also if you have the older shorter coil, you have to modify the plug wires that plugs to the coil. I think 95-97 uses this coil.

[tnrknght]

He needs to find a phase 2 throttle body just like tnrknght have that has a 3 pic iacvI can take a look at local salvage yards and see if I can locate another throttle body otherwise maybe on ebay? (http://www.ebay.com/itm/00-03-Subaru-Legacy-Throttle-Body-Sensor-Idle-Air-Control-Valve-Map-Sensor-OEM-/271089284647?pt=Motors_Car_Truck_Parts_Accessories&fits=Year%3A2000%7CModel%3ALegacy&hash=item3f1e2e3627&vxp=mtr)

[r3v_v3ng3]

It ok, thanks. I don't know if he has the money to pay for it but we will keep checking picknpull inventory for it