View Full Version : Stock ECU adapter. DIY USB Tuning on the fly. (Concept)

22nd June 2011, 02:38 PM
just had an idea need one of these http://www.jaycar.com.au/productView.asp?ID=ZZ8570&keywords=usb+ic&form=KEYWORD

Then design a circuit with the IC linked up to the ECU, so the unit will basically have all male ports for ecu and all female ports, so basically all signals will pass through it to the ECU. (plus a few other wires to other places) The unit will also have a USB port which will provide IO to a laptop running this app:


That's just a starting point but there could be many more adjustable items.

The unit will have to consist of a custom designed PCB by me, the IC in the first link, a few relays, digital potentiometers and digital rheostats to modify sensor outputs, triggers etc at any linear/non-linear fashion according the the tuning in the custom program, in turn tuning the Engine/ECU. This will hopefully eliminate any need to reflash ecu at expensive prices or even getting an aftermarket one. Total cost to estimate should be around $200 per unit. The app will be free, so you should be able to retune yourself at any time you want.

From this stage with a little more work it can well lead to eliminating the stock ECU all together.

Just a thought, what do you think? I also have ideas of creating an iPad/iPhone app to do the same thing instead of using a windows laptop. iPhone will need some different sort of connectivity to the unit, thinking web or iOS app that connects via Bluetooth or WiFi to the device instead of USB.

I need a sponsor because I'm broke as shit and need to get my car running first, but again as the title states, this is only a concept and IMO I think it is feasible. What do you guys think?

22nd June 2011, 03:18 PM
forgot to add, this thing should be able to tuned while its running without flashing the unit, after unplugging usb it will use whatever setting you had setup last, it will be able to save and load profiles etc. forgot to add oxy sensor, but you get the point.

http://randomskate.com/4agetune.exe if you want to download the above app. Virus free. Promise. It will support big/smallport 16v and silver/blacktop 20v 4age's


22nd June 2011, 09:01 PM
Cool idea but from what you've posted, you don't know enough about engine tuning/management to pull it off, yet. You'll probably pick it up quick enough.

You need 3D tables and not 2D adjustments like your AFR adj. Where(what RPM) are you even altering the AFR at? and altering it via changing AFM/MAP voltage up or down or by controlling the ECU injector output? If you are controlling injector output then it becomes a fuel only ECU that you can map out in milliseconds and not a funny +x% here and -y% there thing like e-manage. It works but I dunno, I find it total backwards when you can get a PLUG-IN megasquirt for like 450USD. Yeah, there are uses for E-manage when you need it like auto trans. cars.

If you control ECU MAP in, then you're changing where you are on the ignition map as well which you need to alter even more to get it where you want it. Crazy SAFC-II's.

There's some stuff to think about.

Oh and tuning off ipod touch/iphone is crazy. Screens too small to nav and control stuff. Would be cool for plug-in display.

24th June 2011, 11:37 AM
The app didn't work. Are you sure its not a virus? :) (Is it x64 friendly?)

Yeah unfortunately there's a fair bit more to it than dragging some groupBox's on to a windows form and buying a PIC. A whole lot more.... I'd suggest a couple of books, but they're all Atmel :)

24th June 2011, 02:20 PM
nah its not lol.. on my home PC doesn't work either its x64 haha maybe not friendly.. oh well.. you get the point

I've done a lot of electronics and designing and making printed circuit boards, schematics etc and computer programming since i was like 10yo so i think I'll be right there and i know how to program and flash PICBASIC, I've done IO through parallel and serial ports before just not USB. That is the easy part to be honest I just don't really know enough about the logic behind the ECU it would be cool if i could see they're schematics and source codes or something that shows in detail the logic of the ECU and how it works. Yeah maybe there is some books out there that will explain it.. do you recommend anything specifically?

24th June 2011, 03:39 PM
the app looks good btw? i assume it's .net? vb??

I'd suggest working in C rather than picBasic. Not sure what pic tools there are out there for C but I assume there are many.

24th June 2011, 03:39 PM
Hey! I have PICBASIC too. Can them 4550's do floating point?

Google megamanual and look at a bunch of stuff there, then google msextra manual and look through all that too. There's enough there to build yourself an ecu, if you can be bothered reading through it all. The source code is in the megamanual but it's in C. I'm trying to learn C half-heartedly as I want to make a few changes to ms code.

App doesn't work on xp sp3.

25th June 2011, 04:11 PM
Yeah its vb.net 2010 I probably should of changed the compile settings to make it more compatible but i only mocked that up in like 20-30 mins. yeah i know PHP, Javascript and VB/BASIC but haven't done much C

floating point... i assume so lol.. it might not be the exact PIC i have to use, just stumbled across it
PIC18F2455/2550/4455/4550 Datasheet: http://ww1.microchip.com/downloads/en/DeviceDoc/39632e.pdf

25th June 2011, 04:12 PM
yes it does support:
Support for the entire dsPIC30F instruction set
Support for fixed-point and floating-point data
Command line interface
Rich directive set
Flexible macro language
MPLAB IDE compatibility

25th June 2011, 04:13 PM
i'll have to use MPLAB to program it

25th June 2011, 05:14 PM
I'm getting excited for this.

Gonna be a lot of hard work but if you can get a full ECU working, it'll be awesome.

12th September 2012, 08:45 PM
I hate to sound discouraging, but I don't see this working.

.... At least not in any marketable form... or soon.

There are a few reasons:
You're programming a PIC. Now, I admit, I am biased against them (bad experience). But they kind of suck for complicated things like standalone ECUs. It would be possible to make a basic interceptor type computer, like an SAFC or whatever (more info later).

Do you know what kind of buffering is appropriate for your I/O lines? e.g. you weren't planning on just wiring the CAS signal (which comes the distributor) directly into the Micro?

Also, a lot of the sensor inputs (most of them, actually) are just analog voltages. So you'll need an ADC to measure them. And a DAC to output the modified signal(s). (I dont think a digital pot will work very well.)

Then, if you want to directly modify output signals, theres just further complications, like how to synchronise the micro with the engine speed. This is where you approach standalone ecu functionality. Coding becomes way more complicated.

USB is way more difficult to learn how to work than serial or parallel ports. Most people in this situation would just use something like FTDI so they dont have to worry about dealing too much with usb.

Your software would have to be able to program the device, as well. Like being able to display the graph data. The most basic intercepter will just have a table, 16x16, 16x20, 24x24, whatever you choose. (Ideally, the user would be able to control the resolution). The table would just be RPM vs Load, filled with the modified load values.
Then your code would have to be able to interpolate the map, so it isn't ridiculously crude. That depends on your programming/maths ability, I guess.

Anyway, back to the PIC thing. Did you know you can get ARM cortex M4 development boards on ebay that has a DAC and ADC, along with a USB interface, and enough I/O lines for a full features ECU? for $20?
Of course, they dont have any buffering, or multiplexing on the ADC/DAC. But it would be easy enough to add that.

Or there's the Megasquirt. You're guaranteed to learn a few things about engine management trying to get one of those things to work. Damn good design, I think they just ask a bit too much of the average user. Or even the average tuner for that matter.

Alternatively, some MAF interceptors can be found pretty cheap nowadays. It'd probably be a bit of a challenge to tune one to work with a MAP sensor, though. But not impossible.