ECU tuning - donor car or megasquirt?

I want a tunable ECU, and I don't want to have to spend $1500 on a standalone unit and then still have to make heavy modifications to the engine.

If I buy a newer Subaru (say with EJ253 or something) would it be possible to transplant the motor, transmission, and ECU, with the wiring harness and everything, into my car? Someone in another thread said the place to start looking is at wiring diagrams to see if all the pins match, but if I have a whole donor car to work with how much of the wiring am I likely to be able to swap over?

And finally what would be a good candidate for a donor car to look for if this is the kind of thing I want to do? I just want an engine with an ECU that's tunable. The shop I talked to said they could only tune the factory ECU on something like 01 and newer Legacies.

Let's say my budget is a few thousand dollars, and the motor needs to be pulled anyway, is it better to swap in something newer (and maybe take the transmission from the donor car too), or rebuild the EJ25D and go through with a Megasquirt or Haltech and end up drilling a hole in the intake manifold to accommodate a MAP sensor?

It's not a race car, just a fun car to drive in the snow and dirt. And I like to go fast on the highway.

Thanks

well if you are already committed to a motor, trans, harness and ECU swap, just get a 02-05 wrx EJ20 transplant, and you can just do cobb AP tuning.

I'm not committed to anything, that's the whole point of this thread.

I don't want a Cobb AP or a smaller engine. I want to bring my car to a shop, have them put it on the dyno, tune the ecu themselves, and give the car back to me. I'm not an engineer, I wouldn't even know what to do with all the info and options on the screen trying to tune the ECU myself.

Or get one of the following engine/ecu combinations and go with a tuner who can work with the Carberry Rom from the romraider forums (which would mean features like launch control and ALS):

USDM 02-03 WRX

EDM 01-05 WRX

EDM 03 STI

ADM 01-02 WRX

JDM 02-04 WRX

JDM 02-04 STI

I'm not committed to anything, that's the whole point of this thread.

 

I don't want a Cobb AP or a smaller engine. I want to bring my car to a shop, have them put it on the dyno, tune the ecu themselves, and give the car back to me. I'm not an engineer, I wouldn't even know what to do with all the info and options on the screen trying to tune the ECU myself.

a smaller engine that would make 100hp more than what you have now. a donor car can be had for under $2k, and everything can be bolted in aside from some harness work to get it in to your car. And whats wrong with a Cobb AP?

Or get one of the following engine/ecu combinations and go with a tuner who can work with the Carberry Rom from the romraider forums (which would mean features like launch control and ALS):

 

USDM 02-03 WRX

EDM 01-05 WRX

EDM 03 STI

ADM 01-02 WRX

JDM 02-04 WRX

JDM 02-04 STI

Ok, thanks. I'll run that by the [one] shop [within 100 miles that does Subaru performance work] and see if that's something they can do.

a smaller engine that would make 100hp more than what you have now. a donor car can be had for under $2k, and everything can be bolted in aside from some harness work to get it in to your car. And whats wrong with a Cobb AP?

It makes that much more power with a turbo, I'm guessing? I don't want to turbo this car. The less that can go wrong the better.

And a Cobb AP is just overkill for this build. The Port would just take up space on my dash and never get Accessed. I'm not a mechanical engineer, I don't know what to do with gear charts and fuel maps or whatever the hell other info you get sitting in the driver's seat with a laptop next to you and tweaking all the readings. I'm a biochemist, give me a DNA sequence and I'll dissect it and recode it, but I don't have the time or energy to learn how to reprogram my car's ECU. I just want to take it to a shop one time and have them pop it on the dyno, and give it a tune. That's what my friend did with his 06 GT and it's fast as hell.

Ok, thanks. I'll run that by the [one] shop [within 100 miles that does Subaru performance work] and see if that's something they can do.

 

 

 

It makes that much more power with a turbo, I'm guessing? I don't want to turbo this car. The less that can go wrong the better.

 

huh? then why would you look at any of the suggestions moral hazzard gave you? they are all turbo.

That's what my friend did with his 06 GT and it's fast as hell.

The difference is, your friend's 06 GT already has the parts needed in order to go fast (turbo)

What you are talking about with you car is adapting an entire drive train and wiring to your car....which is a lot different than your friend's 06 GT.

In short, you will not be handing this car over to someone as you describe and receive the car back to your liking.

Where in New England or what shop are you speaking with?

why not just do a hybrid engine build (2.2heads/2.5block or whatever) ? if you're not going boost why are you going to bother with tuning?

Couple reasons, primarily the speed limiter at 113 mph. Would be nice if I could even just swap in the ECU from a 97 GT because I'm pretty sure those didn't get the speed limiter. Second, I thought it was important to adjust the fuel map if you make modifications to the intake and exhaust, which I plan to do.

I've read some stuff here about hybrid motors, haven't looked too deep into it because what I read seemed like people do it for added compression and I don't fully understand what kind of benefits that would provide.

huh? then why would you look at any of the suggestions moral hazzard gave you? they are all turbo.

Oh. I hadn't actually looked further into any of those options, was saying thanks for the list. But yeah I don't want to turbo this car.

The difference is, your friend's 06 GT already has the parts needed in order to go fast (turbo)

 

What you are talking about with you car is adapting an entire drive train and wiring to your car....which is a lot different than your friend's 06 GT.

 

In short, you will not be handing this car over to someone as you describe and receive the car back to your liking.

 

Where in New England or what shop are you speaking with?

Even without a turbo, this car can still go fast... eventually. The highways up here are so straight and long and empty that if it weren't for the speed limiter I'd be able to push 150, albeit not as quickly as my friend's GT.

I'm in northern Maine, the shop is called Baxley's.

Couple reasons, primarily the speed limiter at 113 mph. Would be nice if I could even just swap in the ECU from a 97 GT because I'm pretty sure those didn't get the speed limiter. Second, I thought it was important to adjust the fuel map if you make modifications to the intake and exhaust, which I plan to do.

 

I've read some stuff here about hybrid motors, haven't looked too deep into it because what I read seemed like people do it for added compression and I don't fully understand what kind of benefits that would provide.

IDK about speed limiter, but the computer can adjust for modifications up to a certain degree. NA-T guys run the stock ECU with 6-7 psi and no issues... so your non turbo bolt ons will be fine.

Higher compression = more power. plus you can have your cams reground by deltacam to get even more oomph.

On mobile so I can't quote.

That's good to know about the fuel map, but the speed limiter is still my biggest concern.

If I go through with the EGR delete, what do you think about using a JDM ECU and wiring harness?

With added compression are you also risking premature failure of gaskets?

Do you know about how long Delta cams takes to get the parts back to you? I'm gonna have to buy a $400 beater to drive around if the Legacy is gonna be off the road for a while.

Have to do more research on limiter, I'm sure there's an easy way around it.

If you do a JDM ECU and wiring your car is gonna be down for a long ass time. I think you're over thinking this .

Leave EGR on, it doesn't rob power and its built into the head. Not much weight loss either.

Nah. You'll have new gaskets anyway. Reseal the whole engine obviously, be stupid not to.

Deltacams took about 2 weeks for me. Not too long. If this is your daily I'd buy a 2nd car cause it'll be down for a bit lol

To be fair, in some circumstances a malfunctioning EGR can rob power. But step 0 of making power is to be sure that nothing is malfunctioning.

A correctly functioning EGR loses NO power when you are making power, and slightly reduces pumping losses when you are cruising which is the same as increasing power compared to gas burned.

The only vehicles that had a tuneable ECU were the 02+ WRX, the 05+ Impreza 2.5RS, the Legacy/Outbacks starting in 2005, the 04+ STI, and the 01-14 H6 Outbacks. These are known as 16-bit ECUs, or 32-bit starting with the 05 STI. All of these ECUs are Phase 2 electronics which are not compatible with earlier generations, especially if you are looking at an 05+, which is all CANBUS.

So what to do if you don't want to spend $1500+ on a standalone? Go on eBay and get yourself a Greddy e-Manage Ultimate Blue universal piggyback ECU. They routinely sell for around $250 or less and they splice into your existing harness. Why so cheap? Because everybody who has one grows into a standalone solution when they get crazy with engine swaps. Since these cars' wiring are well documented, it would take someone about an hour and half or so to splice into the factory ECU wiring by matching feature for feature. Just about any tuner that is familiar with Cobb, MS, AEM, and Haltech will be able to put on a base tune and then tweak it to your liking. The Greddy is open source, so the tools are freely available to program it. Stock Subaru ECU maps are freely available on the interwebs, so you can essentially load a stock map to the standalone and tweak it yourself if you like.

All told, for about $300 and weekend of work, you have an ECU you can tune and can easily be reverted back to stock in about an hour, be able to install whatever engine in the car you want without changing your ECU.

Have to do more research on limiter, I'm sure there's an easy way around it.

 

If you do a JDM ECU and wiring your car is gonna be down for a long ass time. I think you're over thinking this .

 

Leave EGR on, it doesn't rob power and its built into the head. Not much weight loss either.

 

Nah. You'll have new gaskets anyway. Reseal the whole engine obviously, be stupid not to.

 

Deltacams took about 2 weeks for me. Not too long. If this is your daily I'd buy a 2nd car cause it'll be down for a bit lol

Thanks for all the input. I just sold my Baja, so I'm down a 2nd car but up in my budget lol. If it's just 2 weeks I think I can get my old lady to drive me around, or just ride a bike if it's nice out

To be fair, in some circumstances a malfunctioning EGR can rob power. But step 0 of making power is to be sure that nothing is malfunctioning.

 

A correctly functioning EGR loses NO power when you are making power, and slightly reduces pumping losses when you are cruising which is the same as increasing power compared to gas burned.

For sure. I've already inspected the EGR and it seems fine, but it's another one of those things where the less things that can go wrong the better. Like sure it's working now but it will eventually start to die and rob power.

The only vehicles that had a tuneable ECU were the 02+ WRX, the 05+ Impreza 2.5RS, the Legacy/Outbacks starting in 2005, the 04+ STI, and the 01-14 H6 Outbacks. These are known as 16-bit ECUs, or 32-bit starting with the 05 STI. All of these ECUs are Phase 2 electronics which are not compatible with earlier generations, especially if you are looking at an 05+, which is all CANBUS.

 

So what to do if you don't want to spend $1500+ on a standalone? Go on eBay and get yourself a Greddy e-Manage Ultimate Blue universal piggyback ECU. They routinely sell for around $250 or less and they splice into your existing harness. Why so cheap? Because everybody who has one grows into a standalone solution when they get crazy with engine swaps. Since these cars' wiring are well documented, it would take someone about an hour and half or so to splice into the factory ECU wiring by matching feature for feature. Just about any tuner that is familiar with Cobb, MS, AEM, and Haltech will be able to put on a base tune and then tweak it to your liking. The Greddy is open source, so the tools are freely available to program it. Stock Subaru ECU maps are freely available on the interwebs, so you can essentially load a stock map to the standalone and tweak it yourself if you like.

 

All told, for about $300 and weekend of work, you have an ECU you can tune and can easily be reverted back to stock in about an hour, be able to install whatever engine in the car you want without changing your ECU.

This is great info, thank you. Do you know of any links to in-depth guides (forum posts, videos, etc) where they talk about doing this kind of thing to a 2nd gen Legacy? If not I'm sure I can find something relevant. Don't want to just dive into it blindly.

My 96 GT has no speed limiter using either the stock 96 GT or 99 Outback SUS ECU. I have un it up to 130 on both. That being said cruise won't set over 110, you have to set it lower and increase the speed using the cruise controls to use cruise at that speed.

Sent from my SAMSUNG-SM-N910A using Tapatalk

My 96 GT has no speed limiter using either the stock 96 GT or 99 Outback SUS ECU. I have un it up to 130 on both. That being said cruise won't set over 110, you have to set it lower and increase the speed using the cruise controls to use cruise at that speed.

 

Sent from my SAMSUNG-SM-N910A using Tapatalk

Yeah it seems like the GTs didn't get the speed limiter, so if all else fails I'll try to look into getting a GT donor car and using that ECU / wiring harness? But I want to look more into that Greddy set up.

Btw here is a video of me hitting the 113 mph speed limiter, idk if you can really tell from the video, but it's like you hit a brick wall while you're accelerating. *link removed, message me if you want to see*

Is yours an auto? My 95 Legacy L standard will hit 130.

nope. stock 5mt.

Buy a '97-'98 GT or '98 Impreza RS ECU on ebay - just ensure it's from a 'Federal' and not a 'California' spec - as they are different due to the Cali emissions. Doesn't need to be from a 5-speed as the ECU's are interchangeable. But as noted you can't tune this ECU.

And if you do need to drive that fast, your tires, brakes and suspension should be up-to-date, too.

Thanks, I'll keep that in mind and post results if that's the route I take.

Current tires are ironically rated to 112 mph, but when I do what I'm talking about I'm also going to get lightweight wheels and put higher-rated tires on them, then keep this A/T set for winter. KYB shocks with less than 20k miles on them, strut bars in front and back... Alignment so straight I can leave my hands off the wheel on a giant straightaway and close my eyes if I wanted... I take good care of that stuff. Eventually doing bigger sway bars and stiffer endlinks, but I haven't had a problem with it the way it is. I had a little bit of understeer after the front sway bar went in but I'm managing it by adjusting my tire pressures based on the weather. There are some days that it's really windy, and I mean really windy, like I've never lived in a place that gets this windy, and sometimes I can really feel it slamming on my car, but that sketches me out and I don't drive fast on those days.

This thread wasn't about suspension, just wanted to assuage your concerns about me driving recklessly. I just want to drive fast. The roads are really straight and empty out here. I might just buy another 92 (or so) Integra because those things are fun as hell. But I don't want to build a track car, I want a touring style car that will go 140+ for hours and handle like a go-kart. But I don't want to just get a newer car because they're too much like computers rather than machines.

I also want to go as fast as possible for as long as possible because according to Einstein, time slows down the closer you get to the speed of light. If you think about it, that means you actually have a longer window of opportunity to react when driving... We're talking fractions of a fraction of a second but sometimes that's all you need. Sadly, I never learned how to fly a plane, and there are no bullet trains near here, so I just have to make my car as fast as possible.

 

....I want a touring style car that will go 140+ for hours and handle like a go-kart. But I don't want to just get a newer car because they're too much like computers rather than machines.

 

I also want to go as fast as possible for as long as possible because according to Einstein, time slows down the closer you get to the speed of light. If you think about it, that means you actually have a longer window of opportunity to react when driving... We're talking fractions of a fraction of a second but sometimes that's all you need. Sadly, I never learned how to fly a plane, and there are no bullet trains near here, so I just have to make my car as fast as possible.

1. Don't you have cops/state patrol? Or you have a really good radar detector? And your Sig states "New England", but sounds like Wyoming. :-)

2. And unless you have advanced physics training (I most certainly do not, so take this w/a grain of space dust) etc, I'm not sure 'time dilation' is relevant @ highway speeds. "Fractions of a second" might show up once you get to near 'c' but @ less than 200MPH? And apparently it's more noticeable the farther you are from the Earth's surface. :-)

1. Don't you have cops/state patrol? Or you have a really good radar detector? And your Sig states "New England", but sounds like Wyoming. :-)

 

2. And unless you have advanced physics training (I most certainly do not, so take this w/a grain of space dust) etc, I'm not sure 'time dilation' is relevant @ highway speeds. "Fractions of a second" might show up once you get to near 'c' but @ less than 200MPH? And apparently it's more noticeable the farther you are from the Earth's surface. :-)

1: Not really. I'm in northern Maine. They patrol hard between Portland and Augusta (with airplanes even, fyi) but once you go north of Bangor there's nothing. I'm talking you miss your exit and it's 10+ miles to the next one. It's not always flat but it is mostly straight.

2: You're on the money. We talked about that example you linked in one of my calculus classes. The people who live in penthouses experience more time than the people who live on the ground floor. This is because they are further away from the center of rotation, which means they cover more distance during one rotation of the earth around its axis. Anyway. Yeah it's more noticeable with people who *live* in penthouses, because you spend so much time where you live. But I want to emulate that in my driving. High speeds for long durations. Oh and I like getting the car sideways from time to time but man do Subarus have good grip.