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Choosing ECU for GC8 Subaru


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Hi! Asking for advice which ECU to get.

I'm choosing between Xtreme, Fury and PNP for v1-2 or v3-4 Subaru, are there major differences in terms of hardware?

Long story is that I'm considering getting myself Link ECU for my GC8 Subaru.

Car is used mostly for trackdays and local time attack competition in street class. I like to log different stuff and tired of doing it in three separate loggers including using PC to log my current ECU. And then going through stitching all the logs together to see the full picture. Car now has fuel, oil and brake pressure sensors, external DCCD controller, oil temp, EGT, WBO2 and none of these signals is currently used or logged by ECU (except log for wideband wired in place of stock narrowband signal). I wanted to add clutch switch, wheel speeds, suspension level sensors, some extra pressure and temp sensors. So basically I want to get new ECU for more inputs, possibility for further expansion via CAN and getting all data in one log. Wiring is modified and while the car was originally V1-V2 (with 4-channel COP ignition), now it's running on V4 ECU (2 channel batch-fire ignition) using patch harness adapter I made. intake manifold is also V3-4 including IAC, throttle, TPS etc. Originally I was thinking about Fury or Xtreme, but reading more now I'm  also looking at PnP versions for V1-V2 or v3-4. I can install wire-in ECU by modifying same patch harness I use now, which is fairly easy, or make completely new harness (original is 20+ years now..) which is interesting but may stall the whole project :)

Plug for V1-V2 physically has more pins(does it matter?), 4 separate ign channels and one less adaptor harness is a good thing as well. But I can't understand if there is any difference in hardware of wire-in and PNP versions. 

I see that Fury has on-board wideband controller but otherwise PNP versions seem to have more inputs/outputs and easier to install.

Also, regarding logging capabilities… It seems that 4Mb in g4+ is quite limiting. Am I supposed to use external loggers via CAN to log longer race sessions, or should I wait for more powerful versions of G4X?

Thank you!

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The plugin ecus are very similar to an xtreme in terms of functionality so they offer pretty good bang for buck.  The disadvantage however is you can be limited by the amount of useful/spare I/O available due to the fixed factory pinout and pin functions.

The V3/4 is very similar to the v1/2 in terms of I/o available but both are a bit limiting.  Neither has DBW auxes available and only 4 extra analog inputs on the expansion connector.

One option is through your dealer you can ask Link to modify a plug-in by manually adding some wires to make the DBW aux 9/10 and a few extra analog inputs available for a small extra charge.  Otherwise the Xtreme or Fury are good options but consider wiring a wire-in ecu will typically add at least the cost of the ecu on top. 

I suggest you download the manuals for the wrx plugins and have a look at the pin function list and the expansion connector pinouts, then make a list of what you need and whether there is enough I/O available 

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  • 1 month later...

It seems that my choice will be v3-4..

So, I checked pinouts and these plug-in ECUs are indeed a bit limiting...

I counted 2 inj and 2 ign outputs,  3 volt inputs and 4 Aux outputs inluding two DBW ones being not available... and one knock sensor input. Xtreme or Fury sound really good but I found great deal on PnP..

I figured out that I can re-purpose some of the IO. like i'll probaly will be fine with 2 ign channels, currently I use IAT on MAF wire with external pullup, aux taken by ac clutch I can  use for something more useful in hot weather like intercooler spray or 0-5v signal for AEM WMI kit waiting for installation...

so there goes another question, are there any in/out extenders that I can use to at least log all data on ECU?

basically I want to keep all engine related sensors on ECU and extra sensors related to chassis or suspension - on CAN extension. Can I use something like TinyIOx for this? it uses megasquirt CAN stream: http://jbperf.com/io_extender/tinyIOx.html#

Also, reading trough manual for v3-4 I noticed some errors like pin 13 is listed twice in pinout table and igniton 1 and 2 channels are assigned not only to pins 4 and 5 respectively as they should be as per subaru pinout, but also to pins 17 and 18 which, I believe, are empty. Is this for some purpose? 

I  also couldn't confirm IAT on  pin 38, it's not listed in diagrams that I have and from what I heard GC8 does not have usable IAT sensor..  I had to install separate GM IAT followng manual for my ECU. My car has PS switch signal there, but it's Frankenstein. 

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6 hours ago, HomebuiltRacing said:

Also, reading trough manual for v3-4 I noticed some errors like pin 13 is listed twice in pinout table and igniton 1 and 2 channels are assigned not only to pins 4 and 5 respectively as they should be as per subaru pinout, but also to pins 17 and 18 which, I believe, are empty. Is this for some purpose? 

Pin 17 & 18 are for the 3rd and 4th coils on some models that had factory direct spark such as the GTB legacy.  So they are paired up with ign 1 & 2 to run in wasted spark.

 

7 hours ago, HomebuiltRacing said:

I  also couldn't confirm IAT on  pin 38, it's not listed in diagrams that I have and from what I heard GC8 does not have usable IAT sensor..  I had to install separate GM IAT followng manual for my ECU. My car has PS switch signal there, but it's Frankenstein. 

The vast majority dont have a factory IAT, some specific models do.  Maybe an "RA" or similar special.

 

7 hours ago, HomebuiltRacing said:

basically I want to keep all engine related sensors on ECU and extra sensors related to chassis or suspension - on CAN extension. Can I use something like TinyIOx for this? it uses megasquirt CAN stream: http://jbperf.com/io_extender/tinyIOx.html#

There are some common things such as EGT, Lambda, oil & fuel press & wheel speeds & steering angle can come in over CAN and be used just like a native wired input.  There are also 8 general purpose "CAN analog volt inputs" but these are not all that useful in a lot of cases as you cant rename them or give them meaningful units (you can still scale it to give some relevant number).  An example to make it clearer might be say brake pressure for instance - you could bring this in over CAN and assign it to "CAN AN Volt 1" but instead of having it displayed/logged as "Front brake press = 600psi", it would be displayed/logged as "CAN AN V1 = 600.0V".  I will attach the current list of CAN inputs that are available below.   I've never looked at the tinyIO (megasquirt CAN is a bit odd), but another common one to look at is the analogX from autosport labs.

TYN1rP7.png

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Wow, this list is significantly extended compared to one I found from earlier messages on this forum!

Looks great! If it works out I will be able to get lambda signal from CAN because that board can receive Innovate serial WBO stream and send it over can. So that way I can have one more analog input  in ECU and have digital signal from WBO controller to ECU without offsets... Unfortunately not the case for my inovate MTX EGT gauge since only WBO stream gets transmitted to CAN.. 

Thank you! ordered my ECU and hope to test it soon! )

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You will need to do a bit more research on the TinyIO CAN format, it may or maynot be useable.  I havent seen much documentation for it.  Much of the Megasquirt CAN is a very odd old school request/respond CAN system similar to serial where the receiving device must send a data request to the device it wants data from.  So for instance the ECU has to say to the lambda device "please send me current lambda", the lambda device then sends just one lambda sample back.  A few milliseconds later the ECU then needs to again say "please send me current lambda" and so on... 

 

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Yes, we discussed this with author of the board and it is working the way you said:

"If you can send CAN messages to then receive the needed data, you would be able to get all the data you want. The speed data would require one message and you'd get back 4 speed values (assuming you use the 16-bit values which should be fine). For analog data, you can get up to 4 values per message and the same for AFR data (assuming you can use CAN data for it)."

 From what I've understood, sending CAN requests is possible with 4g+, is it? Or request-reply will introduce more lag and not optimal for lambda, for example?

As I said, I plan to keep on IO extender all chassis and suspension channels that I want to analyse after track sessions... I just tired of stitching several logs together after each sesdion. It's time consuming and not practical. so I wanted to upgrade electronics and use benefits of can bus. At the same time I can't justify price of dash/logger to tie this all together. I was considering Race Capture and have some experience configuring it (my first experience with CAN in fact) and it's nice, AnalogX only provides 4 analog channels. And if you start on old analog car like GC8 getting all information to the bus can be expensive... That's when I started looking at DIY Autotune, where I poentially can get quite affordable Microsquirt, for example, and use it as IO extender. 

 

Currently on my car I use ESL ECU (daughterboard for original ECU), RaceDAC logger which has 8 analog and 2 digital channels + g-sensor and streams data via Bluetooth, Bluetooth GPS and RaceChrono app on my phone that receives data from all Bluetooth devices and saves it in one log. So, if I want to log engine data, I need to do it from PC connected to the ECU and then somehow stich two logs with different formats and data rates together.

I really like RaceChrono and in their latest build they added CAN communication, need to check that out, have big hopes on that :)

Basically what I believe is possibe is Diy logger which will have gps, accelerometer/gyro, some analog/digital inputs and CAN functionality to get all data from ECU and send it via Bluetooth to RaceChrono. I've seen similar projects done before, but I need to learn a lot to be able to put something like that together and make it all work...

Again, this may sound like something that is available on the market, but I can't justify paying 4-digit price for hobby track car project and I sort of like the DIY process :)

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Got car started on new ECU yesterday! Everything went pretty smooth and car started from the first try!

Have couple of thoughts on how to re-arrange some of the inputs like. My MAF wire is currently IAT with external pull up and PS signal goes to temp 2 IAT channel.. So, I'll probably move MAF wire to Temp 2 and remove pullup to clean the wiring a bit and use some of the spare DI for PS switch...

One thing I couldn't figure out is if there any output for pressure exchange solenoid? I had that whole setup disconnected a while ago, but now before the start I assembled it all together thinking that it would be one less thing to mess things up.

Later I checked and as I understood there is no MAP sensor on board on this version of ECU, and I can't see any outputs assigned to pressure exchange solenoid that Subaru uses to get reference to barometric pressure... So how ECU gets BAP reference? From  my digrams I can see that solenoid should be on pin 8 as per Link diagram, but its not listed in pinout and I can't see shuch function assigned in base map anywhere...

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Oh, got it. I just read somewhere in the manual that only some plugin ECUs have the sensor. Maybe I confused it with onboard MAP... Anyway.. good to know! So, this solenoid can be removed.. that's potentially one more pin in OEM header that could have been used...

Thank you!

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