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 Post subject: DIY exhaust AVCS controller?
PostPosted: Tue Nov 18, 2014 1:07 am 
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Joined: Wed Nov 22, 2006 10:23 pm
Posts: 2428
Hi everybody, long time no see. :)

My oil consumption skyrocketed over the last coupe months, so it's time for me to do a motor build. My car currently has a single-AVCS motor (like every 05 Legacy GT) and I'm thinking about getting a dual-AVCS motor put in.

Of course that would require something to control the exhaust cam timing, so I'm wondering if it would be practical to build an exhaust-AVCS controller around an Arduino or Atmel AVR or similar small microcontroller. If I end up trying this, whatever I come up with will be totally open-source, GPL v2, same as the LC/FFS and SD stuff that I worked on earlier.

I have no worries about the software part of this project - if there's a roadblock here it would be in the hardware to interface the AVCS sensors and actuators with the microcontroller. For that, I could use some help.

Does anyone know where I can find some info about the signals from the exhaust cam angle sensors, and the signals to the oil control valves?

Thanks!

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2005 Legacy GT w/ ATP 3076, IWG, MBC, BCS, BC 272, LC, FFS, OMG
Please don't send me tuning questions via PM - use the forums instead. Thanks!


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 Post subject: Re: DIY exhaust AVCS controller?
PostPosted: Tue Nov 18, 2014 11:05 pm 
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Joined: Thu Jul 23, 2009 1:46 pm
Posts: 852
Hey! Good to see you back!

Definitely check the factory service manual for one of the newer motors. ECU pinout pages and mechanism/function pages may have some info about signal patterns. I don't have a DAVCS FSM but I suppose it wouldn't be very different from the intake setup.

This could get pretty complicated :mrgreen: Either all of the syncing and angle calculation needs to be duplicated in the microcontroller (are they fast enough?), or another sensor input to the ecu needs to be found, and intake avcs angle calculation algorithm needs to be duplicated in the ecu. From there all you need to do is emulate the exhaust avcs control loop.

Perhaps the effort would be better spent getting FreeEMS working?

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 Post subject: Re: DIY exhaust AVCS controller?
PostPosted: Wed Nov 19, 2014 3:41 am 
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Joined: Mon Jan 19, 2009 2:31 pm
Posts: 1372
Location: Saratov, Russia
I would recommend to use JDM LGT ecu MY03/05 or MY06/08, a version that fits your wiring.
Both of them have Dual AVCS from factory.

And spend your skill and effords for new usefull developments.
I personnaly can't wait a logger for Android...


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 Post subject: Re: DIY exhaust AVCS controller?
PostPosted: Wed Nov 19, 2014 12:38 pm 
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Joined: Wed May 20, 2009 9:49 pm
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Location: Canada eh!
Sasha_A80 wrote:
I personnaly can't wait a logger for Android...

Check out http://www.btssm.com/?page=info


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 Post subject: Re: DIY exhaust AVCS controller?
PostPosted: Wed Nov 19, 2014 4:24 pm 
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Joined: Mon Jan 19, 2009 2:31 pm
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Location: Saratov, Russia
dschultz wrote:
Sasha_A80 wrote:
I personnaly can't wait a logger for Android...

Check out http://www.btssm.com/?page=info


NSFW promises an open source or at least free software.
The first approach allows the code to be customized if needed.

As related to btssm I am currently looking for the logger applicable for Joe Sixpack and plain Jane.
They need diagnostics badly and are not going to analize the logs themselves.
BTSSM hardware plus software cost is currently looking overpriced for them.


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 Post subject: Re: DIY exhaust AVCS controller?
PostPosted: Wed Nov 19, 2014 5:05 pm 
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Joined: Wed May 20, 2009 9:49 pm
Posts: 5659
Location: Canada eh!
Sasha_A80 wrote:
NSFW promises an open source or at least free software.
The first approach allows the code to be customized if needed.

As related to btssm I am currently looking for the logger applicable for Joe Sixpack and plain Jane.
They need diagnostics badly and are not going to analize the logs themselves.
BTSSM hardware plus software cost is currently looking overpriced for them.
Of course open source would be the most desirable. I was just pointing out that a solution is available since no open source option exists yet.


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 Post subject: Re: DIY exhaust AVCS controller?
PostPosted: Fri Nov 21, 2014 4:49 am 
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Joined: Wed Nov 22, 2006 10:23 pm
Posts: 2428
I had not thought of the factory service manual but that's a good idea, I'll try that.

Anything Android-related would have to wait for me to get my car back on the road first.

_________________
2005 Legacy GT w/ ATP 3076, IWG, MBC, BCS, BC 272, LC, FFS, OMG
Please don't send me tuning questions via PM - use the forums instead. Thanks!


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 Post subject: Re: DIY exhaust AVCS controller?
PostPosted: Fri Nov 21, 2014 10:09 am 
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Joined: Mon Jan 19, 2009 2:31 pm
Posts: 1372
Location: Saratov, Russia
NSFW wrote:
Anything Android-related would have to wait for me to get my car back on the road first.

Is it high time to help you with JDM ecu conversion ?


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 Post subject: Re: DIY exhaust AVCS controller?
PostPosted: Tue Nov 25, 2014 4:38 am 
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Joined: Wed Nov 22, 2006 10:23 pm
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The most likely thing is just getting another single-AVCS motor, but I haven't ruled out a JDM ECU or a custom AVCS controller.

Apparently the exhaust cams use reluctance sensors, and the actuators are PWM at 300hz, so a custom controller might not be too hard to build.

My biggest worry about the JDM ECU approach is that I'd need to do a lot of connector wiring to make it work - do you know if the connectors are compatible, other than added or removed features like the exhaust AVCS?

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2005 Legacy GT w/ ATP 3076, IWG, MBC, BCS, BC 272, LC, FFS, OMG
Please don't send me tuning questions via PM - use the forums instead. Thanks!


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 Post subject: Re: DIY exhaust AVCS controller?
PostPosted: Tue Nov 25, 2014 6:57 am 
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Joined: Mon Jan 19, 2009 2:31 pm
Posts: 1372
Location: Saratov, Russia
What ecu version are you running?
Do you have an applicable wiring diagram?
I have those for JDM ecu 512kB ( sti04 ) and 1024 kB ( sti05 ).


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 Post subject: Re: DIY exhaust AVCS controller?
PostPosted: Tue Mar 24, 2015 11:15 pm 
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Joined: Tue Dec 13, 2011 9:05 pm
Posts: 31
Location: Terrebonne, Qc
Hi, so as stated here: http://www.romraider.com/forum/viewtopic.php?f=15&t=11570
My 05 OBXT now has a dual avcs engine.
I do beleive I'm having issues because exhaust avcs is always fully retarded...
Could a tgv output be used to control the exhaust avcs???

Thanks

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 Post subject: Re: DIY exhaust AVCS controller?
PostPosted: Fri Mar 27, 2015 2:20 pm 
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Joined: Mon Jul 21, 2014 10:44 am
Posts: 103
Here's another guy coming out of the woodwork too :p Just a good few months late though!

Any progress on this so far? In any event, you should be able to use the TGV outputs to drive the AVCS mov's instead of the micro option. The standard 'duino isn't going to have a high enough clock speed to get you where you want I'm afraid. Plus (as already stated) you'll have to re-sync the whole bugger and that compounds the issue. Back to the TGV option though. Depending on the driver type that's used on that ouput, you could either directly use the TGV driver in the ECU OR wire it into a MOSFET switch to modulate the AVCS mov. I don't *think* you'll need a half-bridge driver...and just a single 'fet should work, but I haven't looked into anything yet.

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 Post subject: Re: DIY exhaust AVCS controller?
PostPosted: Tue Jun 09, 2015 4:51 am 
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Joined: Wed Nov 22, 2006 10:23 pm
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Sorry for the slow response on this. I haven't done anything with this idea, but I haven't replaced my motor yet either.

Using the TGV inputs for this would be challenging because they're intended to measure a voltage and we'd really need the to measure the elapsed time between the crank position sensor and the cam position sensor (if I understand the way the sensors work...). There might be a way to use a simple circuit to turn that timing information into a voltage that the ECU could easily measure, but I don't know enough about electronics to design that circuit.

And then the TGV output would need to be reconfigured to generate a PWM signal instead of (I think) a stepper motor control signals.

I think it would be less work to create a standalone device that measures the pulse timing and generates the PWM signal, perhaps coupled with a boost pressure sensor. Designing that from scratch around a simple microcontroller (Atmel, maybe Arduino) seems like less work than interfacing with the ECU and changing the way the ECU uses those sensors and actuators.

_________________
2005 Legacy GT w/ ATP 3076, IWG, MBC, BCS, BC 272, LC, FFS, OMG
Please don't send me tuning questions via PM - use the forums instead. Thanks!


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 Post subject: Re: DIY exhaust AVCS controller?
PostPosted: Sat Jun 27, 2015 12:24 am 
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Joined: Wed Apr 16, 2008 1:43 pm
Posts: 7
At least for the Legacys, using the JDM ECU is the easiest option. All you need to add is the wiring for the exhaust cam sensors and the solenoids.

FWIW, this is what I'm running in my '06 Legacy GT. The swap was a piece of cake.


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 Post subject: Re: DIY exhaust AVCS controller?
PostPosted: Mon Jul 13, 2015 12:38 am 
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Joined: Sat Sep 17, 2011 11:20 pm
Posts: 41
As NSFW knows already, I'm looking into developing this using a arduino. It should be entirely doable. I'll keep this thread updated as i make progress.

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