ultimate lurker

I was fortunate enough to spend Sunday afternoon with Derrick, one of Hondata's founders. While discussing race cars and playing Gran Turismo, I asked him a lot of questions about the Honda ECU and its functionality.

In particular, I asked him how the short and long term fuel trim numbers applied to WOT operation. He told me that the long term fuel trim _does_ apply during WOT operation. However, the ECU ignores the short term trim data.

So, what does this mean from a tuning perspective? Well, it says that if you require more than 20% enrichment (total) to run well, you're not going to get it at full throttle. Short term and long term both have +/-20% ranges of operation, but you don't want to use up all your long term just to compensate for modifications.

This means that in some cases, additional fuel pressure could be beneficial if you're outside the long term max trim window. It also indicates to me that, until we get a programmable ECU, something like the VAFC, using only the "hi-throttle" function, would be helpful.

Derrick also told me that harnesses should be pretty simple and I plan on stopping by Hondata soon.

On another note, Derrick believes that our ECU may be very expensive to develop in the Hondata line because our microprocessor is very expensive. I'll let them open up my ECU and do a little research to get a more detailed conclusion.

UL

gregstevens

Interesting stuff, UL. I have a stock ECU if they would like to perform some surgery, as wel. (for a price, of couse... )

Let me know if they need one...and thanks, interesting post...

marcucci

Very interesting. If you can, talk to Doug as well- I spoke with him at length on the phone. From our (mine and Doug's) perspective, the cost of the processor isn't limiting, it's availability. Apparently Honda is the only company that's used the Oki 507, 509, and 589 processors in the newer ECUs and Oki is very protective of them. Doug says they red flag any outsiders interested in the chip and generally clam up. I got far enough with a tech and a rep as to get them to check on availability, but haven't had a response back yet. Not sure if Oki Japan is that slow or if they are sending the goons out as we speak...

The development time on our ECUs is quite significant. I suspect it would be much easier/cheaper in the short haul to rewire for an older ECU and experiment with the OBD1 boxes they already support. My concern in getting an "s2k-based" modfied/modifiable ECU is that the OBD1 boxes are going like hotcakes and will eventually become scarce.

If ANYONE has a Mugen ECU and is willing to open it up, I'd like to see if your Oki processor is the same as stock (same chip) or if it is flash programmable (has a Q in the part number). If so, it may be a good idea to pursue the Mugen as the flash parts allow for in-circuit programmability which would allow Hondata to read the code out and reverse engineer it.

Any takers?

Ben

this problem of not being able to reprogram/hack the S2000 ecu was my main problem with developing a turbo kit for the S2000. I was working through UPRD on the project and we contacted Hondata, finding the same information you've found here.

Once they are able to hack into the S2000 ecu, then the turbo project may be back on again. In the meantime, its on hold since a stand alone such as a tec II is simply too expensive to include in a production kit.

When someone is able to hack the S2000 ecu, let me know!

ultimate lurker

Had a conversation ith Doug today. With respect to our ECU, there are two issues. First, the ECU has the code ROM onboard. And this ROM is of course write-once. So in the development process one microprocessor would be needed for each code change. At $80 each in minimum quantity $100 this is rather expensive - although not out of reach.

The second issue is that the uP is security protected. In order to get the info it would require a significant reverse engineering effort (acid etching, laser scanning, etc.) costing many thousands of dollars and that effort would not even be guaranteed success.

Doug would still like to see a Mugen ECU to see if they use a different chip which he could access.

Other than that, our best hope may be that Hondata quickly learns how to access and reprogram the RSX ECU. That ECU is flash reprogrammable and could easily be adapted to our car. At $550 brand new from Honda, Hondata could take the unit and make a conversion for us that is reasonably priced, if not cheap.

UL

Penforhire

UL, regarding development work, couldn't you take a fast laptop PC with an I/O board and simulate the ECU? I know it would look pretty funky having all those wires going from the engine bay into the passenger area. But that would avoid ROM burning until you found the best mapping. I'm not clear on all that the ECU does but isn't it just outputting a few control signals from a few inputs based on a firmware mapping (plus learned trim adjustments)?

josh3io

uhhh...would you want win98 to be running your car? i sure as hell don't

j/k....maybe if you put a stable os on there...but i personally would rather not do it. too many variables could cause computer glitches, and thusly glitching the car.

my first solution, if you have to use the stock microprocessor with only onboard ROM is to put instructions in the ROM to point to external RAM instead that would be even better than having a laptop to emulate.

ultimate lurker

Pen and Josh,

Production versions of the Hondata system do use an emulator system. But during the development process, they have get everything figured out before they can put together an effective emulator. And then there's that issue of the onboard ROM again.

UL

DSF_S2k

This is some very interesting stuff. First off, I work in the embedded microprocessor industry. I want to mention that we use OTP (One Time Programmable) micro's all the time. We code protect the chips, during the programming of the device. Basically the method is that the programmer "burns's" a code protect fuse. It is very hard (if not impossible) to reverse engineer micro's that are code protected without spending major $$$. You basically have to scan the ROM area with an electron microscope. There are also area's of the ROM that are not addressable externally. What is interesting about the discussion above, is that the ECU's must have an area of static RAM or Flash, EEProm to store the trim information. This "Trim" information will be sent in the clear (not code protected). I think that you will find that the Mugen ECU will use the same processor's and will probably have some additional "Signal processing" micro's to modify the map's.

Thank's for the information, Keep us informed.... this is some interesting stuff.


Dale

lupin

Sorry,
but what/who is Hondata??