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Discussion Starter · #1 · (Edited)
The ECU contains a ROM chip holding pre-programmed values for air:fuel across the rpm range, and also for CO1 and CO2, and the rev limiter. The ECU also contains a ROM value for the 'baseline' value that is compared to all sensors after the analog input is converted to digital. We all know its equally as possible to program the Warrior ECU as it is for most cars. What we need is get started is to identify the ECU beyond the cryptic Yamaha part numbers. But all the lists of Mitsubishi ECU part#'s I can find are for Mitsubishi cars, has anyone found a list of ECU's built by Mitsubishi for Yamaha motorcycles?

----- here is a compilation of ECU info that could be modified if we can find a flash-programmer -----

ECU Diagnostic Code Values from a Physical Check by Members
Data From:

1. Stock ECU: 5PX-8591A-01-00 (F8T914 70 5PX-00 1Z28)
Data From:
Stock ECU Values
01 18 Throttle Angle
02 738 Atmospheric Pressure
03 2 Delta Pressure
04 0 Unknown
05 54 Intake temperature
07 0 Vehicle Pulse speed
08 0.6 Lean angle Cut-off Switch 0.4-1.4v
09 12.0 Fuel System Voltage
10 57 Unknown
11 56 Unknown
20 on Side Stand switch
21 on Neutral Switch
30 00 Ignition Coil 1
31 00 Ignition Coil 2
36 00 Injector 1
37 00 Injector 2
50 00 Fuel Injection system relay
52 00 Headlight relay
54 00 Unknown
55 3.1 Unknown
60 00 E2Prom fault code relay
61 15 Malfunction History Code display
62 1 Malfunction History Code Erasure
70 0 Control Number

2a. 02-03 S* ECU: SPD-5PX09-50-04 (F8T914 72 5PX-70 1Z07)
Data From:
2b. ?04+? S* ECU: SPD-5PX09-50-04 (F8T914 72 5PX-70 4928)
Data From:

Speed Star ECU Values

3. Why reprogramming the ECU manually is useless
Data From:
Patrick Racing ECU Conversation - PRWarrior (in 2003)

Here is a brief explanation of what is needed to reprogram your ecu unit for higher revs. A Techtom unit priced new is about $5000.00-$10,000.00. You might be able to get away with a simple plain vanilla EPROM programmer that can be had for about US$150. You need to find one that offers an EPROM emulator for real-time testing. You need to write a disassembler program to convert from binary to human-readable assembly instructions. You will also need to write an emulator program for the ECU's processor so you can do real time testing so you do not damage your motor.

One of the first questions you have to ask yourself is "can I do this myself?". In theory, yes you can. If you learn a considerable amount about computer programming, assembly languages, engine management, electronics, and then study the Warrior Electronic Control Unit (ECU for short) at great length in horrific detail with considerable patience. In practice it just isn't worth it. Nonetheless people persist with this notion because they really don't have any idea about what is involved. To this end I am including a tiny snippet of ROM for you to look at. This is the raw binary from the ROM, displayed in hexadecimal. If you don't know what that is, you'd have to learn about it first. The snippet here is 128 bytes out of 32768.


The snippet above is, of course, completely unreadable to humans. It is a text representation of the program data fed to the computer. Once you've got the numeric data from the ROM (and remember, there is 256 times more of it than I've put here), then you need to find or write yourself a disassembler. Step one is figuring out what the processor is. Step two is finding a disassembler that is good at this type of work. The output of my disassembler looks something like the snippet below. This snippet is 10 lines out of 18,080!

ea21:ff 2c 9b stx [$2c9b] { 5} ;W=x
ea24:7f 2c 98 clr [$2c98] { 6} ;M=0
ea27:b6 8a 92 ldaa [$8a92] { 4} ;a=M
ea2a:b7 2c 99 staa [$2c99] { 4} ;M=a
ea2d:0f sei { 2} ;i=1
ea2e:96 0f ldaa [$000f] { 3} ;a=M
ea30:8a 01 oraa #$01= 1 { 2} ;a|=M
ea32:16 tab { 2} ;b=a
ea33:43 coma { 2} ;a=~a
ea34d 0e std [$000e] { 4} ;W=d
ea36:0e cli { 2} ;i=0

The first part are the numbers from the raw data, and the offset within the data. The second column are actual processor instructions that this raw data represents. The third column is a bit of shorthand notion I added to help me remember what the instruction does and how long it takes the processor to do it.

With all 18,000 lines (about 300 pages) of this arcane text, the task is to figure out exactly what the code is doing, from only a general understanding of engine management principles and based on the specs of a different version of this processor. And I mean exactly, having 18,000 lines if you make one mistake on one line it can drastically affect everything. It is hard to describe to somebody that hasn't tried it just what is involved and how easy it is to make mistakes, both in figuring out what is going on and especially in making changes. This stuff is hard and it takes a great deal of time and patience. If you don't understand the stuff below, forget about figuring out the ROM by yourself, much less trying to make changes.

Rev Limiter Adjustments

The stock ECU program has a rev limiter built into it. When the engine RPM reaches a certain point, the ECU completely shuts off fuel delivery. When the RPM drops far enough the fuel delivery is restored. The stock program is set to restore fuel delivery as soon as the RPM drops below the rev limit value. It is a simple matter (once you have gotten access to the program) to change the rev limits, and change the fuel restoration points. Since the engine's output drops off significantly above a certain RPM (ex…5500rpm), and stress on the engine increases dramatically at higher RPM. There are no fuel maps above the rev-limiter so you must add on to the existing tables, inputting the proper fuel amount for each scenario.

Fuel and Timing Map Adjustments .

There are a variety of data maps in the ECU, including a few which control fuel enrichment (i.e. the choice of an A/F ratio) and ignition timing advance. While I have not looked into the details of modifying these tables I know where they are, how they are organized, and what they mean. It is a simple matter to tweak and tune these tables, but I would only recommend doing so while on a dyno and equipped with a wide-band A/F meter. I have another 12 pages of data concerning engine management that I did not include. If you are curious I can email them to you. As you can clearly see this is time-consuming project, which is why it has not been done to date. If I have bored you to death I am sorry. You have been asking for info on changing the ECU, and personally I would not let anyone I know even attempt to change anything on my ECU.

4. Rev Limiter Thinking
Data From:
Patrick Racing ECU Conversation - PRWarrior (in 2003)

Now for some fun stuff. If you're slamming into the rev-limiter in the first four gears you are losing a lot of power. If you have a dyno sheet on your bike, take a look at the hp curve. The best place to shift is right before the hp curve starts to drop. Once you've shifted, the motor will still be in the powerband. On a fully street PR modified Warrior, I shift at about 4700. Granted, I am shifting pretty quick, but it's the closest I have ever come to being shot out of a cannon.

I also have a FZR1000 that redlines at about 12,500 rpms, but it does not reach the powerband until 8000 rpms. The hp curve starts to drop at about 11,800, so I shift at 11,700. The guys on here who also have sport bikes know that they don't get going until the revs are way up. My point is even on high revving engines, we still only have a few thousand rpm's for a powerband; it's just in a different spot. One more quick thing, the Warrior is by far the best handling cruiser there is, launches like a rocket ship, and looks like the meanest kid on the block. I live by the beach and on my street I see about 500 bikes a weekend. It is funny to see people walk right past the other v-twins to stare at the Warrior. PRWarrior

5. Are there any Interchangable ECU's?
Some posts indicate the Warrior ECU is the same as used for the R1. The last 4 characters of the part# are different, probably indicating different programming. All the lists of Mitsubishi ECU part#'s I can find are for Mitsubishi cars, has anyone found a list of ECU's built by Mitsubishi for Yamaha motorcycles?

691 Posts
You should find someone in your neck of the woods that has a Tatrix cable to see if will plug in to the ECU.... I mean if your thinking it might be the same that would be a place to start. You don't need a Techtom anymore to tune the Mitsu cars, there is a freeware that you can use with the Tatrix cable.


156 Posts
What is it you hope to accomplish with the ECU modification? What is the biggest benefit you can see and what do you think the $ per HP or TQ might be? Just curious because it looks to be a tough andexpensive process.

5,211 Posts
HURD sits in desk with puzzled look on face, his hand moves from mouse quickly on a path to buzz the tower, cusses self for being retarded. Thanks again Arizona!

232 Posts
mxjrb_651 said:
You should find someone in your neck of the woods that has a Tatrix cable to see if will plug in to the ECU.... I mean if your thinking it might be the same that would be a place to start. You don't need a Techtom anymore to tune the Mitsu cars, there is a freeware that you can use with the Tatrix cable.

The Tactrix cable uses the J1962 connector, typically implemented in cars and communicates using one of 3 different OBD-II protocols. These protocols are developed for closed loop ECU’s.
The software used for it is called OpenPort and is the most popular among some others.

ODB-II is supposed to be an industry standard…Well, not quite
: It starts from pins used differently than the standard recommends on the connector and goes down to some “extra codes” not documented of course etc.

Yeah, rules and standards are here to be broken, that’s what you’ll soon find out.

Further, this whole chapter is highly finicky and comes down to the very specifics of the processor used executing the above-mentioned hex code.
Apart from the fact alone that the J1962 connector won’t fit the RSW, I played around with a Tactrix/OpenPort setup on a Mitsubishi Challenger (Shogun Sport in the US), comparing maps and processors with other Mitsubishi’s (the bigger Shogun, EVO’s xx and others) and they are all different. Ergo; Mitshubishi is not equal Mitsubishi.

In most cases ECU’s need to be reversed-engineered and is nothing for people not having a clue about disassemblers (yup! This is plural), even though it has those spelling “Mitsubishi” it can be quite propriaritary, different than OBD-II. And because this black-box/ECU under our ass is not even a closed loop ECU, I am confident that this is a rollercoaster from the best sort.

In a nutshell: Get a PC-III, it is a less expensive solution.

691 Posts
Thanks for the response phat, I have a very limited understanding of tuning as far as programing goes. So your post gave me a better view on the subject thanks!
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