Also note that in the Harley world, VE New = VE * AFF/100 * CLI/100

I have not seen this thing called "VE New" in any other system.

When using other systems, I often Create a field that amounts to "VE New"

VE * AFR / Target AFR

You can also use

VE * Lambda / Target Lambda

I then use MLV HD to "bit bang" thru all the data and create a new VE Table. Essentially creating an autotuned VE table.

Andy

 

I have a sense that this is not being explained in a way that resonates with you. Let me have a very short run at explaining what the ECM does and how Smart Tune works. VERY short and very basic.

The Engine Control Module (ECM) is basically a microprocessor with associated EPROM. In the EPROM are several datasets stored as lookup tables. These datasets contain all of the information that runs the EFI settings, ignition settings, etc.

The ECM constantly gets live data from a multitude of sensors, such as but not limited to: The crank position sensor, which tells the ECM where in the four-stroke cycle each cylinder currently is, which also includes where the cams/valves are, and current rpm. The Intake Air Temp Sensor tells the ECM how cool, dense, and rich in O2 the outside air is. The Manifold Absolute Pressure (MAP) sensor tells the ECM how much suction, or vacuum, exists inside the intake manifold. At the exhaust or output end, the O2 sensors tell the ECM if there is any unused free oxygen in the exhaust gas. There are many more sensors than these, but these will give a picture of what's going on.

The ECM takes all these on-the-fly inputs and, using its programming and lookup tables, decides how much fuel is needed, and whether or not to retard or advance ignition timing. (There's more, but I'm keeping it simple.)

One of the most important lookup tables is the Volumetric Efficiency Table, or VE Table. VE is pretty straightforward. You have a 103 cubic inch engine spinning at 1,000 rpm. There is one intake and exhaust stroke for every two revolutions of the cam. So, at 1,000 rpm the engine will theoretically intake and exhaust 500 * 103, or 51,500 cubic inches of air/fuel mixture and exhaust gases per minute. This represents a VE of 100%, which is converted to a multiplier of 1.0 in the math. However, in the real world, you have an air cleaner clogging up the flow, and throttle body and valve and intake manifold that aren't perfectly smooth, and tiny little valves, and a muffler. So, the actual VE is much less than 100. Most of the time.

The ECM decides how much fuel based on one of two ways: If the engine is running "normally" meaning pretty much a steady cruise, then the engine will take the input from the O2 sensors to determine if the engine has zero O2 in the exhaust gas (could be too rich: used up all the O2), or detectable O2 (could be too lean: not enough gas to use all the O2). The narrow band O2 sensors are only capable of dealing with a pretty small range +/- from the 14.6-ish AFR. A couple tenths either way. Which creates a problem...

At startup, when the engine is cold, it needs a much richer mixture to start. O2 sensors can't handle that. At WOT (Wide Open Throttle) same problem. When the AFR is outside the range of the O2 sensors, the ECM defaults to the VE lookup table. For example, if you're at 3,000 RPM, but you decide to race the clown in the Corvette, and you nail it at 3,000 RPM: you're at WOT, the ECM knows your throttle position, the RPM, the MAP, the air temp, etc., etc., and decides to apply the VE table value that corresponds to 100% throttle at 3,000 RPM and very low MAP, instead of using the input from the O2 sensor.

When you do a Smart Tune, you are updating the values in the lookup tables. There are many, many other settings that you can change, but that's the basic idea.

For example, (and I'm making up these numbers), let's say that for a bone stock motor, the VE table values for 50% throttle at 5,000 RPM is 75. Then, you put on a freer flowing air cleaner and freer flowing exhaust, and now, in order for the ECM to give the bike enough fuel, the VE table value for that throttle position and RPM obviously needs to be higher. Bigger hole on the front end and back end means bigger flow. So, you do a Smart Tune run, take the date you captured on your Vehicle Control Interface module (VCI), load that back into the software, the software looks at the new data, generates a new VE table based on the new air flow, and you take that new table, and update (reflash) the VE table in the ECM.

Now, when you nail the throttle, instead of a VE value of 75 telling the ECM how much fuel to send to the engine, the new VE value is 83.

Does that make more sense?

If you want a really deep dive. pour yourself a coupla fingers of a nice single malt, and go here: http://prosupertuner.harley-davidson...NU/index.html#

[PS: Note to the actual experts, of which I am not one. I've attempted to make this very short, simple, and understandable for someone wanting to learn. If, in attempting to keep it simple, I've screwed something up, let me know and I'll change it.]

 

Thanks Clay, I have PM'ed you.

My main question on the auto tune function, is that bearing in mind the 02 senors don't work at say 14.3 is " How/what does it sense/detect, so that it makes the changes ?"

But I think I'll take a break until someone accurately answers my question.

Thanks

Dave

 

The autotunes can only work effectively very near 14.7 AFR. The narrow band stuff gets very sketchy very fast at trying to verify AFR away from stoich.

This is why Target Tune works so much better. It is way better at verifying AFR at the mixtures that we really want to run the motors.

Andy

 

The Power Vision auto tune basic uses the stock 02 sensors so yep auto tune sets the afr 14.6/7 across the board during the tuning session, it never sees a 14.3 because it doesn't set a 14.3 or any other afr outside of stoich for that matter.

From what I understand the Target Tune will constantly adjust the VEs in real time because it uses broad band sensors.
I find that kind of odd seeing how the VEs are mostly affected by the mechanical layout of the engine or am I missing something here?

 

When I had to develop ways to tune the Sporty years ago, I set the bias to .45 where the O2 sensors were the most active and easy to read. Then I used the AFF and CLI to lead me in the direction that the VE tables needed to be tweaked. The goal is getting the AFF and CLI to average as close to 100 and be active everywhere you are willing to run 14.7 AFR.

Once the VEs were set, I only run closed loop where it was to my advantage to do so. On a Sporty, they are only happy at 14.7 at idle. They really want to run closer to 13.8 to 14 AFR 90% of the time. The stock narrow bands are near flat line at that point and are near useless for tuning.

I essentially run the same basic tune now, but Jamie converted the Cal to a Target Tune Cal. Apparently in the conversion, someone (Harley Engineering, Fuel Moto, Dynojet) finally fixed the Sporty closed loop logic. The motor was transformed to a real motor. It tuned right in.

Andy

 

AFF could you define that term?

 

CLI Closed Loop Integrator. The percentage of fuel that needs to be added to the base fueling to get the AFR to hit the AFR Target. It changes very fast.

AFF Adaptive Fuel Factor A table of average corrections learned from the CLI Can be held in memory even after the motor is killed.

Andy

 

Thanks. I'm an auto tech by trade and some of the terminology used with tuning Harleys varies to a degree.

CLI I remembered but it's an older method and no longer used, I think that might be the change you're seeing with your Sportster's tuning software.

AFF is commonly know as "fuel adaptive strategy" in the car business or just simply put "adaptive strategy" or in other words learned values.

Short and long term fuel trims aren't phrases I've seen on this forum or others so there must be different terms for it.

 

I really think the OP needs to clarify what he means by Auto Tune

Is he referring to the PowerVision Basic Auto Tune?
Is he referring to the PowerVision Pro Auto Tune?
Is he referring to the PowerCommander V Auto Tune function?
Is he referring to something else?

Since most of the responses have been geared toward the PowerVision and EFI systems in general and he claims his questions have not been answered I will take a WAG that he is referring to the PowerCommander V.

Maybe this will help …
All the Auto Tune methods using the DynoJet tuners mentioned above will only work in closed loop.
They work differently and auto tune different things depending on the tuner being used.
Since the PCV Auto Tune module uses wide band sensors it would work.

The OP asked for detailed explanations, and he certainly got some! This thread alone could have saved me reading thousands of other posts and documents to learn this stuff.