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Discussion Starter #1
I have an 07 Impreza 2.5i, I put in an EJ20X, and I'm using an 07 USDM STI ECU. It cranks, and I can hear the fuel pump running, I haven't been able to get a spark. It's throwing a P0345 code, Camshaft Position Sensor “A” Circuit (Bank 2). I replaced the sensor and the wires from sensor to the ECU. I'm assuming this code alone is enough to cause a no start, but if someone knows better let me know. Any guesses?
 

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Hey, that's a neat swap. I was looking at EJ20X/Y stuff before I settled on my EJ204 (read: cheaped out). Do some searching around on Legacy GT forums. I think some 2005-2009 Legacy GT owners have been playing around with swapping their (blown up) EJ255s for EJ20X/Ys for a bit with some successes running them off the stock USDM Legacy GT ECU. IIRC, around that time period there were a couple different possible cam sensors on the EJ engines. Some had VR (should generally be 2 wires from the sensor). Some had Hall-effect (usually 3 wires from the sensor). In addition, there were a couple different cam tooth patterns as well. Find yourself an FSM for a 2007 STI and check out the wiring diagrams. There will also be diagnostics procedures for different codes and pinouts for the cam sensors. You should be able to use the info there to verify that the ECU you're using is actually made to work with the cam sensors you have. If everything should be compatible, and your wiring checks out, it might be a noise issue: Check that the wires carrying your cam trigger signal are shielded and that the shields are grounded the same way Subaru did. If you're still getting no luck, post back here and I'll see if I can shake loose any other ideas from the back of my head.
 

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Discussion Starter #4
Are you certain the STi ecu can run the ej20 engine? Also, is it tuned for your specific engine application?
No? Dumb question here, I'm new to ECU flashing. Can I flash a map made for an EJ20X on this ECU, or will that not work? I may at some point switch to a JDM ECU, so I can run the exhaust AVCS, but I don't want to re-pin everything right now if I don't have to.

Hey, that's a neat swap. I was looking at EJ20X/Y stuff before I settled on my EJ204 (read: cheaped out). Do some searching around on Legacy GT forums. I think some 2005-2009 Legacy GT owners have been playing around with swapping their (blown up) EJ255s for EJ20X/Ys for a bit with some successes running them off the stock USDM Legacy GT ECU. IIRC, around that time period there were a couple different possible cam sensors on the EJ engines. Some had VR (should generally be 2 wires from the sensor). Some had Hall-effect (usually 3 wires from the sensor). In addition, there were a couple different cam tooth patterns as well. Find yourself an FSM for a 2007 STI and check out the wiring diagrams. There will also be diagnostics procedures for different codes and pinouts for the cam sensors. You should be able to use the info there to verify that the ECU you're using is actually made to work with the cam sensors you have. If everything should be compatible, and your wiring checks out, it might be a noise issue: Check that the wires carrying your cam trigger signal are shielded and that the shields are grounded the same way Subaru did. If you're still getting no luck, post back here and I'll see if I can shake loose any other ideas from the back of my head.
As near as I can tell, the EJ20X and 07 STI sensors are exactly the same part, both 3 wire. I didn't realize there were different tooth patterns with the same sensor, I'll look into that. Would both sides throw a code if the pattern was wrong? I have the FSM for the 05 JDM Legacy (I'm 90% sure that's where the engine came from), and the 07 Impreza/WRX/STI. I double checked the wiring, ran new cam sensor signal and ground wires, and ran through the diagnostic procedures in the manual. The FSM didn't show shielding on those wires but...a bunch of other stuff did. So maybe I'm missing shielding somewhere else and that's causing the problem? Or maybe I should shield the cam sensor wires just in case? I'll do both, nothing to loose I guess. Might be a few days before I get to it, I'll post when it's done either way.
 

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No? Dumb question here, I'm new to ECU flashing. Can I flash a map made for an EJ20X on this ECU, or will that not work? I may at some point switch to a JDM ECU, so I can run the exhaust AVCS, but I don't want to re-pin everything right now if I don't have to.
I don't know much about OEM ECU stuff (I went straight to an aftermarket ECU with my swap), but I'd take a look at what the ROMRaider guys are doing with extracting and flashing maps. If both the ECUs are actually using the same chip, then maybe that's possible?

As near as I can tell, the EJ20X and 07 STI sensors are exactly the same part, both 3 wire. I didn't realize there were different tooth patterns with the same sensor, I'll look into that. Would both sides throw a code if the pattern was wrong? I have the FSM for the 05 JDM Legacy (I'm 90% sure that's where the engine came from), and the 07 Impreza/WRX/STI. I double checked the wiring, ran new cam sensor signal and ground wires, and ran through the diagnostic procedures in the manual. The FSM didn't show shielding on those wires but...a bunch of other stuff did. So maybe I'm missing shielding somewhere else and that's causing the problem? Or maybe I should shield the cam sensor wires just in case? I'll do both, nothing to loose I guess. Might be a few days before I get to it, I'll post when it's done either way.
Yeah, I would expect it to trigger for both cam sensors, so that's kinda weird. I also wouldn't expect a code related to "circuit" to be triggered for the wrong number of teeth, but again I skipped all the OEM ECU stuff entirely. Shielding "shouldn't" be as important on Hall-effect sensors as it is on VR sensors. Did you already look at the diagnostics procedure for that code in the FSM?

If you've got an oscilloscope (even a cheap one) I'd definitely check out the waveform for the left and right cam trigger sensor and just visually compare what you're getting

If you don't have an oscope, you could try something like unplugging the fuel pump and coils and then swapping the inputs for the left and right cam trigger into the ECU to see if the error moves or changes.
 

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Likely the EJ20x ECU and STI ECU you have are slightly different and the tune cant be directly loaded. However, you should be able to find the OEM EJ20x somewhere online and modify the currently STI tune to match as closely as possible. The issue is some tables are larger than others or there are more of them.

Dont know what to tell you on the code. I would shield the wire anyway. Even if it is a hall sensor there is still alot of noise in the engine bay and the sensors are close to the coils and fuel injectors. Both put off lots of noise when in close proximity.

If you did the timing belt I would verify your timing. I know on old Subaru's that can cause issues as well.
 

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Discussion Starter #7
Ok here's the update. It was throwing codes for both sides, I just wasn't cranking long enough for the second code to show up. I ran the shielded wires for both sides, signal and ground, and both codes are gone. I can crank forever, no codes.

Still... no spark as far as I can tell. I may just break down and buy a JDM ECU that was built for this engine anyway, but at least I got the cam sensors working (I think).
 

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When I had an aftermarket immobilizer the car would just crank and crank forever when it was engaged (it killed ignition/ecu power). I would safely guess that the ecu isn't talking to the engine harness since the same thing is happening in your case.

A lot of Subaru parts are interchangeable, but if you just grab an ECU without tuning it for your specific engine application it may not work correctly, or at all.
 

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Also, Subaru started adding immobilizers directly to their ECUs at some point. I'm really reaching to a dusty corner of my memory here, but I seem to recall something about some immobilizer equipped ECUs needing to talk to a gauge cluster with a matching "code" before they'd actually run the car. I wouldn't grab a JDM ECU unless you can verify that it's not actually equipped with an immobilizer as well. Also, take all this with a grain of salt, just something I vageuly remember reading like 1 or 2 years ago. Anyways, this is part of the reason I just went aftermarket. :)
 

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I forgot about the factory immobilizer, that started in 2005 I believe. I remember reading that you needed key+ecu+immobilizer to match. We don't know for sure the state of OP's ECU since it was likely used. I also don't know if a tuner can disable the immobilizer. I always used '04 stuff because of this.
 

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I bet the immobilizer is the issue, just like the others have said. I used to have JDM STI heads from a GR (people call them version 10, but that's not an official designation), those were also quad avcs. I'm interested in whether the 2007 STI ecu can control this engine (or the "version 10") though.
 

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Discussion Starter #13
Yeah, I think you guys are right, probably an immobilizer issue. I got the key/immobilizer/ECU set all together, but I'm guessing they don't really match. So, looking for a new (used) ECU now. I would like an ECU that can at least run the intake AVCS. Looking at JDM, the Legacy/STI ECUs would all be immobilized, and I'm struggling to find someone selling the whole set. The 01-05 JDM WRX uses VR cam sensors I believe, I've seen converters from VR to hall signals, but not the other way around. The 04 USDM STI and Forester XT did not have immobilizers, but I haven't found one yet. I would love a stand alone aftermarket ECU, but $1500+ is right out for this swap, haha. If I could find one for ~$400 or less I'd jump on it. Heck for simplicity's sake I'd swap another 07 STI set in there, but I can't find one of those either.

I don't even care about the immobilizer working, I'm not worried about someone stealing a base model 14 year old Impreza around here. I'd just as soon bypass the thing if I could, oh well.
 

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Is it possible to flash an 07 STI ecu with an 04's immobilizer-less code?
 

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So, here's where I'm at on standalones: I ran a Speeduino on my EJ204 swap for the first ... year or so. It's a good system and was very reliable (except when the heater core leaked on it), but it's going to be missing some features you probably want: DBW throttle, built-in knock sensor support and I don't think they have Subaru AVCS support yet. When I got into it I was optimistically thinking I'd adapt the existing VVT code to control Subaru AVCS, but I never really got motivated.

Last December (and into January) I actually rewired things (god I'm so tired of wiring) and put in an ECUMaster EMU Black. That has been very nice to work with from both a tuning and hardware perspective. I snagged mine for ~$1100 (with a free oil pressure sensor as part of a Black Friday deal). At that price it's a really good deal. I still haven't gotten the AVCS going, but that's mainly because I wanted to put together a base tune first and because i have one more round of rewiring (switch to DBW throttle, wire in AVCS, buy aftermarket knock sensor since it won't work right with the Subaru OEM one). All a long way of saying: I can recommend the EMU Black, but I haven't tested all the features you'd want yet.

I'm 100% out of my depth on the immobilizer stuff so I have no idea if it makes more sense to try and defeat it (which should be possible given how old the tech is now) or just try for another matched set. It might be worth trying to absolutely confirm that the symptoms you see from your ECU match what Subaru describes in the FSM for the immobilizer (if they even document it). It'd be a shame if it's actually some other silly wiring thing (and god knows I've created really similar no-start scenarios in my swap without having an immobilizer involved).
 
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