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 Post subject: Re: DIY exhaust AVCS controller?
PostPosted: Sun Dec 27, 2015 7:03 am 
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I made a down payment last week on a built motor with dual-AVCS heads. :) If all goes well I should be driving it (with "full retard" exhaust cams) before the end of January.

Nitros, have you learned anything new about the cam position signals since the last time we talked?

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 Post subject: Re: DIY exhaust AVCS controller?
PostPosted: Sun Dec 27, 2015 11:58 am 
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never go full retard.


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 Post subject: Re: DIY exhaust AVCS controller?
PostPosted: Sun Dec 27, 2015 3:21 pm 
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 Post subject: Re: DIY exhaust AVCS controller?
PostPosted: Wed Jan 13, 2016 11:36 pm 
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NSFW wrote:
I made a down payment last week on a built motor with dual-AVCS heads. :) If all goes well I should be driving it (with "full retard" exhaust cams) before the end of January.

Nitros, have you learned anything new about the cam position signals since the last time we talked?



not much. i haven't looked into it since august. i decided to build another stroker engine engine. The electronics piece is where I'm lacking. I hope to start looking into it again, I should have my new engine done early feb or late jan.

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 Post subject: Re: DIY exhaust AVCS controller?
PostPosted: Sat Feb 20, 2016 2:11 am 
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It turns out that the cams actually go full advance with no power to the solenoids. Which is a shame because "full retard" had so many possibilities. Oh well.

I bought an Arduino Due because I think the higher resolution timers will be useful. And I found some sample code:

http://forum.arduino.cc/index.php?topic=158361.0

That's all I have to report, though.

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 Post subject: Re: DIY exhaust AVCS controller?
PostPosted: Fri Feb 26, 2016 2:42 am 
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Got my car back, with the dual-AVCS motor and pigtails for the exhaust AVCS sensors and one actuator - will pick up the 2nd actuator pigtail later. The motor has also got a hose running straight from the compressor nipple to the wastegate actuator, which will stay that way until the exhaust cams are under control. I also got an old/dead exhaust AVCS cam pulley to play with, which is kind of neat. Pics later, after I take it apart. :D

Some random thoughts about what I have in mind for the cam controller... I'm basically just thinking out loud here, if anyone has feedback I'm listening:

Take power from the battery, and switch it on and off with the presence/absence of the +5v power at the TGV sensor connectors. Fewer wires through the firewall that way.

Use one TGV sensor input to show the exhaust cam angle, for logging, e.g. 0v = full retard, 5v = full advance.

Use the other TGV sensor input for system status, e.g. 5v = all good, 4v = problem A, 3v = problem B, etc.

Might use a VR sensor board ( http://jbperf.com/dual_VR/v2_1.html ) to get a crank signal, might add my own sensor somewhere instead. This is the biggest open issue right now. Piggybacking off the stock sensor has a lot of advantages, so I bought one of those boards... but I'm kidna nervous about two things - first, I could fry the ECU if I screw up. Second, I could inadvertently degrade the signal to the ECU and maybe cause it to lose sync, and either go into a limp more or worse, like maybe screwing up the ignition timing. Part of me thinks it should be safe to wire that board in parallel as that's basically what piggyback ECUs do. Part of me wants to connect to the ECU in as few ways as possible. Not sure which way to go here.

Either way, I'm expecting to have a fairly small and simple circuit board that contains everything that interfaces with the ECU, and gets power and ground from the TGV sensor connectors. That board will have opto-isolated connections to the rest of the system (Arduino + sensors + actuators + etc). So everything that interfaces with the ECU will be running on power from the ECU, and the only connections between that stuff and the Arduino will be optical.

Some basic tasks to work on:

  • Power the Arduino, as described above.
  • Interface an Arduino DAC output to a TGV input, prove I can get information from the Arduino into data logs that way.
  • Attach an LCD screen to the Arduino, write random stuff to it.
  • Interface the cam sensors to Arduino inputs, and get pulse-timing info onto the LCD.
  • Get a crank signal of one sort or another. Show RPM on the LCD.
  • Hook up a potentiometer, show 0-100 on the LCD.
  • Connect to my boost sensor, show PSI on the LCD.

And the more interesting tasks:

  • Combine the crank signal with the cam sensor signal and (magic happens here) and then show something proportional to the cam angle on the LCD.
  • Use the pot to control an AVCS solenoid and vary the duty cycle a bit and hopefully watch the cam angle value change.
  • Vary the angle from min to max, use the resulting timing information to get cam angle shown in degrees.
  • Write code to produce a cam angle based on the pot signal.
  • Write code to get the target cam angle from an RPM-vs-MAP table.

I'll do some experimenting with tuning at wastegate boost, just to see how different AVCS settings affect spool and power, but I'm going to take the car back to the shop for tuning up to full power. I spent too much on this motor to blow it up, and I don't really want to tune it again. Plus I actually went stage-2 on my wife's car a couple years ago, and still haven't finished tuning it.

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 Post subject: Re: DIY exhaust AVCS controller?
PostPosted: Fri May 13, 2016 1:20 am 
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I have a little bit of progress to report...

Today I got an Arduino Due to listen to the signal from a cam position sensor. It's just bench testing, but with help from some co-workers it worked nicely. Surprisingly simple too. The sensor needs 12 volts, which was a bit of a surprise, but the output is normally floating and gets pulled to ground when you wave a piece of metal past it... so we just wired it directly to an input pin, and configured the pin with a pull-up resistor, and no other parts were required. Calling digitalRead() returns a 0 or 1 depending on whether there's metal in front of the sensor. Ta-da! :)

One of my co-workers suggested using a Zener diode and a couple resistors to protect the Arduino from high-voltage surprises from the sensor, so I'll add that, and post a wiring diagram and some pictures.

I used a 3D printer to make a little box to hold the Arduino and two PLX sensor modules, for oil pressure and oil temperature. The Arduino is going to listen to the serial data from the temperature sensor, and use that to enable AVCS when the oil pressure reaches 140F or so, since the car already does this sort of thing based on water temperature. It will also inject a couple other bits of data into the PLX serial stream, for logging purposes (probably RPM, cam angle, and a status/error code). Seems more elegant than using the TGV sensor inputs.

Also found a solid-state relay that I can use to trigger boost cut if the Arduino has trouble reading any of its sensors. That will set off a CEL at the same time, and I kinda like this idea.

Instead of tapping into the ECU's crank position sensor, I am going to try using an optical sensor to track a dot of white paint on a cam pulley. That will minimize the chances of me killing my ECU or just interfering with it.

Next steps:
* Make some changes to the 3D model of the box, print another one, mount it in the car
* Make a wiring harness for the cam sensors, hook them up, get the Arduino to display RPM from both of them
* Mount the optical sensor, hook that up, get the Arduino to display RPM from that as well.
* calculate cam angles from all three sets of signals
* spend an unknown amount of time chasing down signal-quality issues from one more sensors.
* add PLX serial data
* add boost cut
* add outputs for the AVCS solenoids
* make AVCS happen, just at a fixed angle initially
* spend an unknown amount of time tuning the feedback loops
* add boost sensor, and a boost-vs-RPM table

At the rate things are going, that's about one week per bullet-point, plus who-knows-how-much time for surprises. It's tempting to just clock the cam gears a couple teeth so I can actually enjoy the car this summer while I work on this stuff. Then put them back to factory timing specs for the last three bullet points. (Right now, at wastegate boost, my big-turbo/build-motor hot rod it is actually less fun to drive than my bone-stock Outback XT... Decisions, decisions.)

I'll put what I have on Github with source code wiring diagrams, etc, when I get to the "calculate cam angles" step, if not sooner.

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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: Wed Jul 13, 2016 5:22 am 
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Progress is glacially slow, but progress is happening.

Off to the left is a little board I used to test an AVCS sensor and an optical sensor that I hope to use for a crank position reference (it'll be pointed at a cam pulley actually, just because they're easier to reach). PLX oil temp and pressure stuff is baked into the same case, partly because the factory tune doesn't enable AVCS until the engine warms up (they use coolant temp as a reference, I'll use oil temp) and partly because, well, I wanted them and I had to put them somewhere.

This hasn't been tested with the car yet but I'm working on the wiring harness now. The software is mostly written but I'm sure it will need work when it meets the real world.


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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: Fri Jan 27, 2017 1:46 pm 
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Joined: Thu Apr 30, 2009 2:05 am
Posts: 38
Any more progress?
Ive always thought work like this would be great for those that have swapped an avcs motor into a bugeye.


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 Post subject: Re: DIY exhaust AVCS controller?
PostPosted: Mon Feb 20, 2017 12:24 am 
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Not much progress. I got it reading the exhaust cam sensor signals and showing RPM from them. Also got the optical sensor installed in the fan belt cover, but I still need to paint the cam pulley so the sensor will have something to trigger on. I will be getting back to this in a couple/few weeks though, starting with the painting.

It should work fine for intake AVCS, but the pulses from intake cam sensors are different so whoever tries that first might end up doing some beta-testing before it really works. But, I wrote the software to interpret those signals already (by mistake - I misread a diagram) so it shouldn't take too much effort to make it work.

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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: Thu Mar 02, 2017 9:19 pm 
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Joined: Mon Oct 10, 2016 1:19 pm
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hi guys i do the swap alot at my shop and we send the car and a jdm ecu to the russian guys :P and he take only the chip for the key in the north american ecu to put in the jdm ecu that work perfectly and i can read and sometime i can open it !!! i work in a Jdm shop mecanic









sorry for my english im from mtl


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 Post subject: Re: DIY exhaust AVCS controller?
PostPosted: Tue May 09, 2017 12:11 pm 
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Joined: Mon Feb 16, 2009 5:17 pm
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I'm not much help but I have a running EJ20X in an 04 FXT using the FXT ECU. I'm knocking my head on how to get the exhaust AVCS working. I've tried 04 JDM Legacy GT ECU which looks for the immobilizer and my car doesn't give the signal at all so it's a paper weight. I've tried bench reflashing using unbrick technique and I keep getting an error about ECU being 0.18um etc and I can't find anything about it so will assume it's immobilizer related. I'm willing to test some ideas or assemble some things for testing. I'm not interested into going with a full stand alone ECU.
Thanks,
Randy


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 Post subject: Re: DIY exhaust AVCS controller?
PostPosted: Thu May 11, 2017 12:20 pm 
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Joined: Sat Sep 17, 2011 11:20 pm
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So you guys transfer some electronics form US ecu into the JDM ecu and it works?

Cbast wrote:
hi guys i do the swap alot at my shop and we send the car and a jdm ecu to the russian guys :P and he take only the chip for the key in the north american ecu to put in the jdm ecu that work perfectly and i can read and sometime i can open it !!! i work in a Jdm shop mecanic









sorry for my english im from mtl

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