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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: 4AGE stock ECU programmable
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Sat, 03 January 2004 01:43
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Thanks for the replies
With my modified stock ECU you can remap the engine with just a laptop. All you need is a laptop with a serial port.
At present the remapping software is pretty crude (but effective!). The maps are held in a simple text file and this can be edited with a PC and then compiled and uploaded to the car via the serial port. I will improve on this in the future. The diagnostics GUI and datalogging software is a lot better. See the link on my first post.
Also you get access to ALL the stock maps.
ie warmup fuel maps (lots of these) air temp correction map, throttle enrichment map, startup map, VE fuel maps (several of these), high load fuel correction map, idle fuel map, battery volts map, basic ignition map, idle ignition map, warmup ignition correction map, 'transient' fuel correction maps and more…
Also Rev limiter on/off thresholds and TVIS on/off thresholds.
Also you get full diagnostics/datalogging to check out the results of the remapping during and after a test drive. With this system it is possible to datalog and display all the individual correction factors that contribute towards the final EFI pulse width. This is very useful after remapping when viewing the results.
I am sure Nippon Denso (MR2 ECU manufacturer) would have had a similar setup all those years ago when they mapped the first MR2. They would have monitored all the same things. The hidden diagnostic capability of this ECU is very powerful, you can ask the ECU what things you want data for and it will tell you...
The UK AW11 MR2 uses Speed Density and therefore has a MAP sensor. The fuel mapping is very complex on this car. There are LOTS of maps that contribute to the overall fuelling. Aftermarket systems tend to be a bit simpler to program/understand as they tend to use a much simpler mapping system.
The ignition mapping is far more straightforward. On the 1985 UK MR2 the basic ignition map is a 17x8 (rpm x load) lookup table. I can increase the size/resolution of this map in the code if required, eg 22x12.
The US MR2 has an AFM I believe (and also an O2 sensor?). I would need an ECU to play with to see if my reprog mods will work on the US NA ECU. The fuel mapping will be very different to the UK ECU and I would have to wade through all the code and maps to see what makes it ‘tick’.
I could literally write a book on what I have found inside the UK MR2 ROM code. The ECU has secret fuel/ignition maps, secret modes, hidden diagnostics and more!
I deserve a medal for all this research!!
Jeremy
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it soudns like he takes out the ROM chip, replaces it with an EPROM. on the board at http://www.jmross.freeserve.co.uk/page1.html
there looks to be a MAX232 type serial communications chip, a crystal to set the 232 clock speed, and the three wires coming out go to a serial port on a puta.
this is pretty similar to how the Megasquirt communicates to a computer, and should be relatively easy to do for someone with hardware knowledge.
the dificult part is that the ROM is probably in binary code, so you need to extract the mapping information out of it.... and then be able to recompile the data that goes into the ROM chip as binary once you have made changes... interesting that it only has 17 (should be 16) by 8 RPM/load points....
also interesting that pulsewidth only goes up to 8ms... the injectors could be made a lot smaller...
Cya, Stewart
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