Power Vision 3, Let's Take A Look Inside Our ECU

hulkss

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Let's take a look at what the Power Vision 3 can do for us (I have no affiliation with DynoJet or any other tuners).

I'm going to put aside what has been posted about Flash Tuning the ST. I'll just discuss what I can see and do with the PV3 software without a PV3 connected. If it looks good, and my new bike feels like it could benefit, maybe I'll buy one.

If you want to play along, you can download the DynoJet Power Core software here: Tuning Software Link

DynoJet Support sent me a stock tuning file which is attached to this post. You'll need that too. Change the txt file name extension to stk.

Please comment or ask any questions you have. Somebody will probably be able to answer. I'm not a professional tuner, but I can probably manage my way with this thread.

First up:

Let's look at a Drive-By-Wire table. The Twist Grip and Throttle are connected by wires and the Engine Control Unit (ECU) is in the middle. This gives us control over the progressive feel of the twist grip to engine response.

Throttle.png

This is from gears 4-6 in Sport Mode. Some would say: "Hey, I can't command full throttle until 4000 rpm." Well, that's because the throttles are large and the engine is only pumping about 50% of its air capacity at half speed. If you did open the throttle more at low rpm you won't get any more output. I would not mess with the curve at 100% twist grip. You could apply this map to gears 1-3 which are just a little bit lower in throttle position.

Now, somebody always says: "I wish I had a cable throttle, I like the feel of that better." Well, here you go, the throttle map will look like this:


Cable.png

Bottom Line: You can create a custom throttle map for each gear in Sports or Touring mode.
 

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hulkss

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Next: What about closed loop operation with the narrow band O2 (Lambda) sensors? The table that enables it is called Adaptive Learning.
If the engine is not accelerating (you are cruising), this table (same in all gears) shows when the ECU enters closed-loop control.

Closed Loop.png

Bottom LIne: The ECU is using the O2 sensors for feedback and operating near to a stoichiometric air/fuel ratio at throttle openings below 40% while cruising below 5000 rpm. What if you put in gas with 10% alcohol? The ECU will automatically compensate because the sensors actually measure the Lambda Ratio not the Air/Fuel ratio. If you open the throttle to accelerate, the engine will automatically go open-loop and enrichen the air/fuel ratio, so, closed loop mode does not hurt performance. Just set the red cells to zero and say bye-bye to Adaptive Learning Mode if you wish.
 

MileageMonster

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I am no expert in this matter, but does this mean that alterations interfere with effectivity of the original system?
 

hulkss

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For sure, any alterations of the ECU programming changes the original system. The goal is to do it in a good way to suit rider preferences and not in a damaging way.

For example, I generally do NOT change the following commonly altered items in the tables:
Increase the engine rev limit: It is at 8250 rpm which is plenty high for me and the engine.
Increase the vehicle speed limit: It is at 186 mph, not a problem for me.
Lower the fan temperatures: The fan turns on at 221 degrees F. (50/50 antifreeze/water @ 15 psi boils at 267 F). Use full synthetic 15W50 oil for good hot oil film thickness.
Increase the spark advance: The spark tables are set a little conservative in case you can't get 91 octane fuel or the engine develops a little carbon build-up in the combustion chambers.
Completely defeat closed loop operation: Cruising near Stoichiometric burns clean with minimum carbon build-up and improves fuel efficiency.
Allow wide open throttle at low rpms: It actually reduces performance if you open the throttle beyond the flow capacity of the engine at a given rpm.
Make wide open throttle fueling leaner for more power: The factory air/fuel ratio at wide open throttle is quite rich (around 12.5). This is to protect the engine by reducing exhaust gas temperature.

I usually DO change the throttle progressivity maps to my preference. I will also change the fueling if I notice the engine stumbling, surging, or in other ways acting too lean. I'll look at the fuel injection control next.
 

hulkss

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On to the fuel injection strategy - is this engine controlled by "Alpha N" (throttle position and rpm) or "Speed Density" (rpm and air density in the intake as calculated from Manifold Absolute Pressure (MAP) and temperature? The answer is new to me as it is both. A switching and blending strategy for the two methods is performed by "Alpha N Biasing".

bias.png

I put those somewhat confusing notes and the bias values into a spreadsheet and out came the following table:

bias table.png

The green area is Speed Density (0% Alpha N), the Orange is Alpha N (100% Alpha N), and the blue is a blend of the two (% Alpha N shown).

Bottom Line: Pretty clever are the engineers at Yamaha blending both control methods together.
 

hulkss

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In the Airflow category there are four Volumetric Efficiency (VE) tables. One for each cylinder both Alpha N and Speed Density. The % indicates how much air the engine actually pumps compared to a calculated 100% based on rpm and engine displacement. These are measured with a lot of work on a dynamometer. If you have stock exhaust don't mess with them. Here's an Alpha N VE map for cylinder 2:

VE.png

Bottom Line: Engine flow is at or near 100% at wide open throttle (WOT). No big peaks or dips in air flow. A very well behaved engine.
 

hulkss

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Yamaha uses an Air/Fuel Ratio (AFR) factor table to control fueling (lower numbers are richer, higher numbers are leaner). The top red plateau is the closed loop area for cruising. The AFR here would be close to Stoichiometric (14.7 for gasoline). Use the factors to scale down from there into the rich blue areas.

afr.png

You basically can't enrichen the closed loop area much as the O2 (Lambda) sensors only work over a very narrow band. About +/- 3% as shown in this graph:

graph.gif

You can make the closed loop area smaller by using the first table in this post. Then make the new open loop areas richer while keeping the same basic shape to the fuel map.

Bottom line: Looks pretty typical, however, the lean zone is kind of big extending well above normal highway speed limits (5000 rpm) and to fairly heavy throttle (40%). Consider your top cruising RPM and use the PV3 to "data log" throttle position and then trim back the closed loop area and enrichen the surrounding fuel cells.
 

hulkss

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Does your bike stumble a little when you open the throttle? The key to avoiding this is called Acceleration Enrichment. It works like an accelerator pump on a carburetor, giving the bike a shot of fuel.

Yamha has two tables, one for gears 4-6 and one for gears 1-3 (the transition gear between tables can be changed). Let's look at them. Here's 4-6:

Hi Enrichment.png

I f you open the throttle quickly, you get a shot of fuel. That's good. You could lower the onset of this a little if needed.

Now for gears 1-3:

Low Enrichment.png

Now this is LAME. No enrichment at all for gears 1-3. Booo......If your bike hesitates when you open the throttle in gears 1-3 here is where you fix it. I suppose using the 4-6 table would be a starting point. Carburetor accelerator pumps never knew what gear you were in.

Bottom Line: Significant improvement looks possible for throttle response in gears 1-3.
 
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hulkss

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New to me are the Deceleration Engine Braking Tables. They look like this in Sports Mode:

sports braking.png

And like this in Tour Mode:

Tour Braking.png

There is also a deceleration fuel cut that works above 3300 rpm. That will shut off fuel instead of coasting at the idle throttle opening.

Fuel cut.png

Bottom Line: There is total flexibility to tune Engine Braking and the Deceleration Fuel Cut to your liking, on a per gear basis if desired.
 

hulkss

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Here's one of the Ignition timing maps. As far as I know, the engine does not have knock sensors to protect it. I would leave the timing as is.

Timing.png

Bottom Line - Typical spark map. If you will ALWAYS have 91+ octane fuel, maybe you can add a couple degrees of advance.
 

hulkss

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Here's a nice feature. In addition to the MAP sensors for Speed Density mode, there is a separate Atmospheric or Barometric pressure sensor. This will adjust for weather and altitude when running open loop in Alpha N mode.

baro.png

Bottom Line: A good feature to have with the multi-mode control strategy. It keeps the Mass Air Flow calculations accurate.
 

Jlq1969

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New blood, new ideas. If I had to suggest something, it would be to change the title of the post and add something referring to “ECU REFLASH”……..so that it will be easy for anyone to find this post in the future.
Regarding the analysis of the PV3, excellent and complete….
 

hulkss

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New blood, new ideas. If I had to suggest something, it would be to change the title of the post and add something referring to “ECU REFLASH”……..so that it will be easy for anyone to find this post in the future.
Regarding the analysis of the PV3, excellent and complete….
Thanks, I'll post about doing a reflash with the PV3 if I feel the bike needs it and that the PV3 can address the issues. I'l be getting my '21 ST after the snow melts around here.
 

Jlq1969

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Can the PV3 read the throttle butterflies opening map?….Map I mean the throttle butterflies are not directly controlled by the throttle wire. This controls the position sensor and this sensor, the position of the butterflies. If you say that there is a "restrictive" fuel map for the first three gears, it is probably also restricting the opening of the butterflies in the same first three gears.
 

hulkss

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Can the PV3 read the throttle butterflies opening map?….Map I mean the throttle butterflies are not directly controlled by the throttle wire. This controls the position sensor and this sensor, the position of the butterflies. If you say that there is a "restrictive" fuel map for the first three gears, it is probably also restricting the opening of the butterflies in the same first three gears.
Yes, see the drive-by-wire comments in the first post of this thread.

You can certainly program the throttle to open farther and faster at low to mid rpm in the first three gears. I'm not sure if you would get more power, but you will certainly feel the power come on faster.

The only significant "restriction" I see is the lack of Acceleration Enrichment in the first three gears.
 
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hulkss

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It seems that the PV-3 is a very capable tool. If your powertrain is stock and you plan to keep it that way you can consider the following changes with the PV-3 if your bike is not performing to your liking.

1. Adjust throttle progressively to your preference. There is a huge range of adjustment possible. You could copy the gear 4-6 tables to gears 1-3 for example.
2. Adjust the engine braking to your preference, again a huge range of adjustment is possible.
3. Add acceleration enrichment to the lower gears. I think this will provide a noticeable improvement in throttle response.
4. Reduce the range of Closed-Loop control to match your top cruising speed and cruise throttle opening (use the PV-3 to log rpm and throttle opening), then add fuel to the Alpha N AFR factor table in the cells that are now open-loop, keeping the same basic profile to the fuel map.
5. Richen the fueling near and at idle by raising the minimum rpm for Closed-Loop control and add fuel to the Speed Density AFR table.

You can edit the table axis values if desired and there is an adaptive rescaling option where new cell values are automatically interpolated for the new axis.

These changes can personalize the bike to you without altering the design intent from Yamaha, risking engine damage, or tossing out the emission controls.
 
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