Welcome to the North American Subaru Impreza Owners Club Friday April 29, 2016
Home Forums WikiNASIOC Products Store Modifications Upgrade Garage
NASIOC
Go Back   NASIOC > NASIOC Technical > Factory 2.0L Turbo Powertrain (EJ Series Factory 2.0L Turbo)

Welcome to NASIOC - The world's largest online community for Subaru enthusiasts!
Welcome to the NASIOC.com Subaru forum.

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, free of charge, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, so please join our community today!

If you have any problems with the registration process or your account login, please contact us.
* Registered users of the site do not see these ads. 
Reply
 
Thread Tools Display Modes
Old 12-31-2001, 06:08 PM   #1
john banks
Scooby Specialist
 
Member#: 11669
Join Date: Oct 2001
Location: UK
Vehicle:
Evo IX 345 WHP

Default EBC using PIC 16F84, factory solenoid and duty cycle map with correction

There have been numerous threads on creating an EBC with many interesting ideas. I thought I would update you on where I am at.

The factory solenoid can be used successfully by aftermarket ECUs anywhere from 14 Hz (OEM) 15Hz (Unichip) 45 Hz (GEMS) and apparently tolerates up to 100% duty cycle and can give excellent control.

Using a PIC 16F84 (I already have a programmer) I propose to find RPM and use a duty cycle to the factory solenoid of 100% up to 2300rpm and 100% over 5000rpm therefore giving the flow limit of the turbo. Between these engine speeds I would shoot for 18PSI held. This is what I currently run safely within compressor efficiency maps with good fuelling and ignition advance and no knock with a MBC/bleed. I would implement a 19-20PSI over 0.5 second reduction in solenoid duty cycle which is like the original ECU but higher up by a few PSI. I would use a suitable resistor across the ECU solenoid outputs. I am still working on what sort of modulation to use with TPS voltage. I will probably transform the duty cycle with this.

The solenoid would be driven using a PIC output, a power transistor and a diode.

Once the duty cycles are about right, I will then enable an error correction algorithm to change the duty cycle map in the EEPROM (which can be done by the PIC).

My fuel cut on my Prodrive ECU is already about 1.3 bar sustained for 2 seconds, but for those with original ECUs they could add a MAP sensor transformation map to compress the area from 16-19 PSI into the top end to avoid fuel cut. This is apparently what the Prodrive ECU does, and the ECUs use the MAF sensor to control fuelling. The ignition advance at least on MY00 and before ECUs has very little input from MAP data and is thought to be mainly MAF and knock sensor controlled.

The scheme I have outlined has some similarities to some aftermarket ECUs - certainly the Unichip's boost control module works with a static map based on RPM for solenoid duty cycle and good results can be achieved.

Any comments/further criticisms/coding ideas welcome.

I think it is worth implementing this with a PIC rather than analogue circuits. They are cheap (<$10), 8,18 or 40 pin DILs which can be programmed in circuit and could be very effective for this task. Their performance is easily up to this task.

I may need to think about an alternative PIC which has A/D and D/A onboard.

But I think my first project will be to get the solenoid controlled by the PIC, the RPM measured and try a static duty cycle map initially with no error correction, cutout functionality, TPS compensation or remapped MAP voltages to keep it all simple and see if the project is a goer. This would give MBC levels of functionality plus the ability to change the boost at different engine speeds.

The error correction and TPS features will be very useful to add, but both will need A to D conversion and more complex code.
* Registered users of the site do not see these ads.

Last edited by john banks; 12-31-2001 at 06:51 PM.
john banks is offline   Reply With Quote
Sponsored Links
* Registered users of the site do not see these ads.
Old 12-31-2001, 07:01 PM   #2
ellisnc
Scooby Specialist
 
Member#: 4229
Join Date: Feb 2001
Location: Dublin, OH, USA
Vehicle:
2003 S2000
Did someone say track day

Default

john,

this is the same thing I was ranting about the other day is that right? I think this is pretty cool. One thing I can suggest is if you want to sell this to other people (I realize that that's not your motivation for doing this) you should design some kind of VB or little C++ program to allow people to plug a laptop to the little box and upload a changed map.
I don't think you're going to find many people around here wanting to run 18psi on the stock turbo as our car generally runs a lot stronger on around 14.5-15 psi with the stock ecu.

also another thing to keep in mind is the resolution of your maps. Do you have any idea the kind of memory space you'll have left over for the actual map? 20x20 or 40x40 would be awesome, probably too much. There can't be that much code and I bet there's a lot that you can just find prewritten for this kind of thing. I mean just reading a 3D map...

I don't know if that part you're using has programming pins so that it would even be possible to do in-circuit programming. I have used an FPGA part before that allows in circuit RS232 communication with it, but I'm not as familiar with UCs.

anyway, goodluck PM me if you want to dicuss anything or I guess just post it here is cool too

later
ellisnc is offline   Reply With Quote
Old 01-01-2002, 04:26 AM   #3
john banks
Scooby Specialist
 
Member#: 11669
Join Date: Oct 2001
Location: UK
Vehicle:
Evo IX 345 WHP

Default

They are all of a similar broad idea, but everyone's approach to the thing is different in terms of duty cycle/fuzzy logic/error correction/closed loop/open loop.

The ideas are taken from multiple sources - the threads off here - the MRT TMS1 and my and midlifecrisis threads as well as some you might not have seen:
http://www.mr2.com/ARTICLE/FCD.html
http://www.scoobynet.co.uk/bbs/threa...threadid=61711
http://www.scoobynet.co.uk/bbs/threa...threadid=61862
http://www.scoobynet.co.uk/bbs/threa...threadid=61876


The above duty cycle is using a VF23 and a different restrictor but you get the idea of how the Unichip does it - thanks to Theo for this picture.

Happy wading through that lot - some do not seem to be on topic but the Scoobynet threads have had some considerable detail discussing closed loop boost control systems even though some of them are about MBCs.

I am not planning to sell it - I can make much more as a medical doctor than I ever could from this. A good idea that works on a small scale or open source is a completely different matter to producing something on a commercial scale as we all know.

The devices I am planning on using allow in circuit programming with 2 pins.

18 PSI - yes it is probably the sensible limit, but can be done safely with the original ECU - at least on the old shape - the Prodrive ECUs apparently just compresses the upper range of the MAP voltages and uses the stock fuelling and ignition advance based on MAF. I anticipate that the software will be so simple that it would be easy to change the duty cycle map. If it had error correction it could take a few runs to reset itself if you changed the boost targets.

Obviously with all the right checks I am saying I think it probably is safe to run 17 or 18PSI on the original ECU using MAP compression. Midrange is the place to have it. At the top end the turbo won't flow enough to go much over 13.5PSI at 6500rpm on my car and most other old shape UK cars. New shape may be different.

The Prodrive ECUs runnning 17PSI in the midrange in the UK have only a decat centre section, change of backbox/tailpipe, and some uprated intercooler hose. Subaru leave your 3 year warranty intact and I gather there have been zero engine failures due directly to this package.

In terms of reprogramming, I am looking at my programmer now - it has a 9 pin D plug for RS232, two caps, about 20 resistors or diodes, a toggle switch and a 7400N. I am sure someone could add this to the design and then you have your serial port.

Regarding MAPs - I wasn't planning a 3D map. TPS transformation could I think be done without a map by a proportional or fixed modifier - which could if necessary be looked up off a separate map. For duty cycle most aftermarket ECUs seem to use 400rpm increments - so the map would only be 10 bytes between 2200rpm and 5800rpm - outside these ranges you could just leave the duty cycle at 100%. I can't see any need for interpolation - it will be smooth as I am only actively changing the duty cycle in the midrange - otherwise I am running to the flow limit of the turbo, which to me seems ideally matched to our engine's volumetric properties since it seems to boost just right outside the midrange by leaving the wastegate shut!

Last edited by john banks; 01-01-2002 at 04:50 AM.
john banks is offline   Reply With Quote
Old 01-01-2002, 05:59 PM   #4
midlifecrisis
Scooby Specialist
 
Member#: 3958
Join Date: Feb 2001
Chapter/Region: MWSOC
Location: Minnesota
Vehicle:
2008 Impreza STi
+ '93 & '98 Impreza L(s)

Thumbs up

Sounds good John!

Please let us know how it goes. There may be some issues above some (unknown) duty cycle creating some oscillations or spikes (may be why the unichip is more apt to have these issues), but it is absolutely worth a try. It is likely that higher frequencies will mean less duty cycle resolution, especially as you approach the physical limits of the solenoid. If you need a better (or dual) solenoid(s), I may be able to get you some. Best of luck to you.

BTW, seeing the DOS unichip program screen intrigues me; is the software available to anyone? I would love to be able to adjust mine as I make mods. Thanks.

Paul
red02wrx
midlifecrisis is offline   Reply With Quote
Old 01-01-2002, 06:01 PM   #5
john banks
Scooby Specialist
 
Member#: 11669
Join Date: Oct 2001
Location: UK
Vehicle:
Evo IX 345 WHP

Default

I don't think the software is easily available and don't know what sort of interface it would need. This is a screen dump sent to me from someone that was setting it up with the mapper using the mapper's equipment.

I am considering a BASIC compiler for the PIC which looks like it could work very well. I am much better at BASIC than C or assembler.

Have a look at this Flash presentation and then tell me the programming and circuits don't look temptingly simple - this is new to me as well, but looking at this page is quite encouraging. I have wanted to learn to program PICs for a while and this seems just the thing.
http://www.letbasic.com/pro_vs_plus.htm
john banks is offline   Reply With Quote
Old 01-01-2002, 06:21 PM   #6
midlifecrisis
Scooby Specialist
 
Member#: 3958
Join Date: Feb 2001
Chapter/Region: MWSOC
Location: Minnesota
Vehicle:
2008 Impreza STi
+ '93 & '98 Impreza L(s)

Default

Hey John.

That was a very cool demo. With a change in ON/OFF timing based on RPM, it essentially gave you the code to do what you want! Ok, so I need the PIC ProBasic compiler, my PC and what kind of interface to the PIC? How much $? I didn't see the cost of the compiler, but you may be able to do what is necessary with the free version - that is until you add the TPS parameter. Excellent.

BTW, happy new year!

Paul
red02wrx
midlifecrisis is offline   Reply With Quote
Old 01-01-2002, 06:35 PM   #7
john banks
Scooby Specialist
 
Member#: 11669
Join Date: Oct 2001
Location: UK
Vehicle:
Evo IX 345 WHP

Default

http://www.google.com/search?sourcei...ivided+by+four
http://www.dontronics.com/bs4.html

The link in the last post gives a price of 50 (about $75) for what looks like an excellent bit of software. I already have a PIC programmer which cost 25 ($37).

The two links above are for what looks like a FREE basic compiler for PICs, but I need to look into it more.

The best bit of the BASIC compiler you watched the flash presentation of is that it has programmable PWM and there is a quick way of making AD and DA using a cap and resistor.

Getting late for my bed over here but I will post more as I find out. I don't mind spending a bit - my main task here is for personal education into using PICs. My boost control is actually pretty good with my MBC and it is working better for me than many people's ECU remaps in terms of driveability and performance.
john banks is offline   Reply With Quote
Old 01-02-2002, 06:32 PM   #8
john banks
Scooby Specialist
 
Member#: 11669
Join Date: Oct 2001
Location: UK
Vehicle:
Evo IX 345 WHP

Default

http://www.dontronics.com/runavr.html

This link has a no parts programmer for the Atmel 90S2313-10 which is a PIC with 2K of program space which runs at 10 MIPS and costs $5. The best bit is a free basic compiler (limited to 2K program) and free programming software. The compiler comes with a well written example rich 208 page manual. Looks very good to me. It also has on board RS232 UART abilities and I think PWM as well.

Take a look and tell me what you think....
john banks is offline   Reply With Quote
Old 01-02-2002, 07:17 PM   #9
midlifecrisis
Scooby Specialist
 
Member#: 3958
Join Date: Feb 2001
Chapter/Region: MWSOC
Location: Minnesota
Vehicle:
2008 Impreza STi
+ '93 & '98 Impreza L(s)

Default

John,

Looks like an excellent starting point. Still a bit confused about the cables/connectors, etc. The US$69, doesn't get you that, does it?

Paul
red02wrx
midlifecrisis is offline   Reply With Quote
Old 01-02-2002, 10:31 PM   #10
sponaugle
Scooby Specialist
 
Member#: 4498
Join Date: Feb 2001
Chapter/Region: NWIC
Location: Portland, Oregon
Vehicle:
WRX H6-3.0 Turbo
www.surgelinetuning.com

Default

I'd love to help out with this. I've done several car relate PIC things, and I think I still have the code I wrote for the 73A series that uses the Capture/Compare module to measure RPM (very accuratly... for acceleration and HP testing).

The PICs are great fun to program, and what you are suggesting would be pretty easy to do! I also used a backlit LCD display and keypad to change settings. (It was a serial display from Scott Electronics).

-jeff
[email protected]
sponaugle is offline   Reply With Quote
Old 01-03-2002, 09:44 AM   #11
john banks
Scooby Specialist
 
Member#: 11669
Join Date: Oct 2001
Location: UK
Vehicle:
Evo IX 345 WHP

Default

Would you reference any documentation you made on this here or email me?
john banks is offline   Reply With Quote
Old 01-07-2002, 02:08 PM   #12
GoodFinder
Scooby Specialist
 
Member#: 8943
Join Date: Aug 2001
Chapter/Region: TXIC
Location: San Marcos, TX
Vehicle:
2006 MINI + Corvette
Both Blue

Default

... keep us posted since this is an issue that is relevant to many of us here on i-club !

GoodFinder
GoodFinder is offline   Reply With Quote
Old 01-07-2002, 02:58 PM   #13
Wrxtasy
Scooby Newbie
 
Member#: 4649
Join Date: Mar 2001
Location: Edmonton,Alberta,Canada
Vehicle:
2002 WRX
'88 323 GTX

Default

Check this guy out! He did the electronic boost thing.


http://www.force8.demon.co.uk/impreza/
Wrxtasy is offline   Reply With Quote
Old 01-07-2002, 03:29 PM   #14
john banks
Scooby Specialist
 
Member#: 11669
Join Date: Oct 2001
Location: UK
Vehicle:
Evo IX 345 WHP

Default

I emailed him a while back but got no reply.
john banks is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Throttle duty cycle mapping table hmanxx Open Source Reflashes 17 01-19-2008 12:01 AM
Install of AEM boost contral solenoid and gm 3bar map s. ShadowWRX77 Factory 2.0L Turbo Powertrain (EJ Series Factory 2.0L Turbo) 1 05-22-2007 12:34 AM
Need pics of factory speakers and tweeters. cwcaudio Car Audio, Video & Security 3 06-28-2003 02:22 AM
question about injectors and duty cycle tdxflex Factory 2.0L Turbo Powertrain (EJ Series Factory 2.0L Turbo) 5 01-23-2003 12:34 PM
Understanding AVC-R solenoid duty cycle... SilverSubie Factory 2.0L Turbo Powertrain (EJ Series Factory 2.0L Turbo) 7 05-15-2001 07:22 PM

All times are GMT -4. The time now is 08:54 PM.


Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2016, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2016 Axivo Inc.
Copyright ©1999 - 2016, North American Subaru Impreza Owners Club, Inc.