ECM Swap (not a typical swap)

Hello everyone, long time lurker, first post.

Cutting to the chase here because I'm looking to make a purchase for said parts and looking to do this next spring once my neon gets to be road worthy.

I'm sporting a:

98 Legacy L

EJ22E/4EAT

I've been scowling over google, NASOIC, and various other forums to find particular information regarding an ECM Swap to a newer "open" ECM. I wish to go this route as I'm not fond of piggybacks, and as I do enjoy a good standalone(MS/RUSefi, etc) I wanna do something a little different and unorthodox I guess.

I believe the Legacy ECMs went open in 05 or 06(can source one easily) and I believe the STIs were open since 04?

 

I'm aware that the ECM and their wiring is different but where I was looking for aid was what issues would I encounter aside from wiring(which isn't a major problem) i.e. what sensors would be different or incompatible, vehicles communication bus etc. ECM/TCM problems etc.

Though there is a 5/6MT in this cars future, and maybe boost, I still want to see what I can accomplish with the ecm. Plus I enjoy oddball challenges as such. I don't know when exactly these went drive by wire but I'd imagine I could swap TBs or I got a link with a machine shop, also have an expert in harnesses and wiring ready to aid me in what Im seeking to accomplish

Any help will be greatly appreciated

 

 

The Wolf

 

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I'd start with the FSM for your car and the donor year. List all the sensors in each from the engine wiring section. Then look up each of those sensors and see what crosses. From there you can swap out the ones that don't cross. The hard part will be if the crank and cam sensor star wheels have different geometry, and if you can get the ECU to talk to the TCU at all. Then depending on how bad the chasis canbus stuff is you might have all kinds of trouble with A/C, windows, lights, etc. You might end up with a 98 chassis and all 05 parts.

My advice if you have future plans to include a 5MT/6MT swap and boost is to go with a standalone ECU. You can build an adapter to use your stock wiring harness so you're not cutting up your harness prematurely. There are numerous benefits to this because you can find a stock rom and tweak it how you want to, effectively creating your own tune. When you swap engines for that turbo motor, no worries, reflash the ECU and load the rom for the new engine and tune away.

 

I know you you were looking for a stock solution, but the skinny behind that is there are only two ECU's that will fit, 96-99 EJ25 and a 96-98 EJ22. The fuel maps are damn near identical and will not yield any benefit to swapping it.

 

When you start taking about 2000+ ECU's, you're in a world of hurt. The majority of the post-99 cars had extra sensors, extra pins on sensors, and sensors drastically relocated 06+ Legacy, Outback, WRX, Impreza, Forester, and the 05+ STI were CANBUS ECU's. Those vehicles share NOTHING in terms of electronics with previous models. These are sometimes referred to as Phase 3 or Phase 2.5 cars. Any NA car prior to that uses a different pinout configuration with very similar harnesses to the pre-2000 models. We call these Phase 2 cars. Everything prior to 1999, with the exception of the 99 Legacy Outback and Legacy GT was a Phase 1.

 

If you get a chance, search my Phase 1 to Phase 2 conversion thread. There is a lot of interesting information on the project that I abandoned regarding conversions between Phase 1 and Phase 2, which includes 4EAT transmissions.

 

TL;DR: In short, there is no single ECU or wiring harness that will provide enough flexibility that a standalone solution will. Your options are limited: either go standalone or pick an engine/tranny combo and get the matching ECU and harness and start the tedious process of doing a harness merge/replace. I'm going to be replacing my stock ECU with a standalone unit for my future swap.

Hmm good info.

I was unsure of how you guys did the"phasing" but from what I'm gathering from your post. It's not possible period, motors are too different to even attempt such.

And as far as mating goes I got a guy that can build adapter harnesses shame though, was hoping to do something different.

 

Stand alone option, I'm familiar with MS somewhat, but found it to be a pita to initially configure in the Neon world ended up selling to a friend's for his 350.

 

What other options are there as a formidable solution for a Subaru?

 

Also what about mode 23 on stock ecm?

Wouldn't mind picking a look at that either.

 

Also would there be any advantage to running phase2?(I think I've looked over ypur thread before)

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I too have found megasquirt to be a little bit cumbersome for our engines. They're built to be pretty universal, but with our ignition systems you have to really know how to configure them to work right.

 

I have been mulling over either a Greddy eManage ECU or piecing together a Haltech 550 ECU. AEM also makes a pretty solid solution too, but most guys I know use them for LS swaps. Greddy ECUs are no longer sold new, but you can find them super cheap on eBay for around $400-500. AEM is also in the same price range, though I can't find much on it. Haltech is the creme-de-la-creme when it comes to standalone units, and their price shows. New Haltech 550 units sell for around $1100 with harness, used maybe a couple hundred less.

 

Building a plug-n-play adapter harness isn't difficult. When I was actively in my project, I used a ECU header from a junkyard ECU that matched the car's existing harness and soldered connectors onto it to the corresponding pins for the ECU harness I wanted to use (in reference to my thread). It wasn't pretty, but it was a proof of concept that actually worked. I was actually able to use a Phase 2 ECU in my Phase 1 car. I lost interest in the project because I picked up a JDM H6 motor for my fiance's 3rd gen that I was swapping and then right after that picked up an 02 Fozzy project.

 

The NA ECU's don't have Mode 23 at all, IIRC, hence why they can't be accessed to reprogram them. Not to mention, they have a very small ROM chip size, they aren't ideal for anything. I've been monkeying around with the EZ30 ECU I have at the prospect of reprogramming it, but that is a whole different animal altogether. Mode 23 really applies to the turbo ECU's, which have completely different harnesses.

 

The real advantage over running Phase 2 over Phase 1 is the availability of the motors. Phase 1 lasted until 98 (99 on the LGT and OBW) and the prospect of finding a turnkey motor with low mileage is hard. Phase 2 motors are easy to find with lower mileage and even without lower mileage, they're easier to find in rebuildable condition. The blocks are mechanically similar to the Phase 1, with some differences internally, which is why some of us are taking EJ251s and putting our older EJ25D heads on them. Electronically, they're not. Not to mention around 01 or 02, Subaru switched to a MAP sensor instead of a MAF sensor.

If you get a chance, search my Phase 1 to Phase 2 conversion thread. There is a lot of interesting information on the project that I abandoned regarding conversions between Phase 1 and Phase 2, which includes 4EAT transmissions.

 

Hmm, I have been trying to find any info about doing a phase 1 to phase 2 transmission swap. I'll try to find your thread.

 

OP, if you want to swap ecus you are best of doing a complete harness merge, or better yet having iWire do it for you. If you want to boost your car buy a wrecked WRX or STI so you have everything you need otherwise you will spend the rest of your life sourcing stupid little bits and pieces.