91-94 ECU reprog (Honcho ?)

[asylum]

I did not found any clear information but I saw some posts from Honcho saying that it is possible to reprogram the 91-94 ECU. I think this is a "budget" way to have a good map on lightly modified cars without going to the hardcore Ecutek or AEM. A friend of mine did reprog his track S2000 (only I/H/E mods) with a very nice result. I mean, I really saw on track that his car was pushing harder on straights. Really impressive in the mid range. But he had to go the AEM way. So if we can get such a result by reprog of the stock ECU, that would be great.

Is it possible to know a bit more about this mod ?
Does this imply to open the ECU to implant something ? A communication cable ?
The reprog is done via a specific programm on a PC ? Can it be done by a local tuner that is used to reprog with AEM, Ecutek and so on ? The goal is to have the reprog done localy on the dyno with a wideband.

Thanks for the infos.

 

[Honcho]

It is fully possible to tune the 91-94 ECU. You will need the Moates Demon II piggyback unit, TunerPro RT software, at least one wideband O2 sensor, and some modification of the factory ECU board. You need to talk to @MotorMouth93, since he is the real expert here. However, the basic steps are:

1. Solder wire leads to the TX, RX and GND (G6) holes on the ECU board
2. Remove the factory EPROM from the ECU and solder a ZIF socket
3. Modify the Demon II to re-locate the data pins to the top of the board and install the Demon in the ZIF socket
4. Install the O2 sensor on the front or rear (or both) header
5. Load the factory tune .bin file into Tunerpro
6. Start tuning!

Here is a picture of my ECU with the Demon unit installed. I made a pigtail connector for the wideband so that I wouldn't have to take the cover on and off.

 

[asylum]

Thanks a lot for the answer. I did not understand all the details (TX, RX, GND, ZIF, ...) but it seems clear for a professional. Who can do these "physical" mods ? I mean, I have to send the ECU to @MotorMouth93 or can a local electronics here in Europe make theses modifications if he gets the instructions ?

If I do not want to modify my ECU, I can modify one I buy ? I mean, the 91-94 ECU are not coded with an anti-theft system linked to the keys, right ?

Have you ever made a reprog on a i/h/e modified car and what gains did you get ? I am sure there is something to gain especially mid-range.

 

[mskrotzki]

A local electronics shop in Europe can make the (minor) modifications to any 91-94 ECU, your present one or one you buy. If you hate any changes you can easily plug in your original "chip" and do nothing else -- back to stock performance.

If you really want to get into this (which I highly recommend) go to this google docs site. Be prepared to spend at least a week of evenings absorbing all the information.

NSX Tuning Development – Google Drive

drive.google.com

I have modified my fuel maps (at least maps 3 and 5), and while I don't have measurements of any power differences (aside from my butt) I can say that I am getting greatly improved fuel mileage -- consistently at 29 - 31 mpg (8.1 - 7.6 l/100Km) while driving like a sane person. I have the RDX injectors installed, and the maps that came with that kit were crazy rich. Map changes are not huge, but they seem to have a substantial improvement in all aspects of performance -- power, economy and (likely) emissions.

After absorbing this enormous amount of information, Hocho or I or motormouth93 or jvtech will be available to answer questions.

It's a fun journey and you'll learn lots.