Anyone have a good explanation of how this works on the 07 ECM?

 

What do you mean? Closed-loop operation? Information about that abounds on the Internet.

The engine's operational characteristics (mainly amount of air moved through the system in this case) are used to derive a baseline amount of fuel at any condition the engine will see. There is a device in the exhaust stream which detects the amount of oxygen present in the gases passing by. It generates a voltage based on the amount of oxygen it detects and the engine control computer monitors that output. If the output is higher than the target value there is not enough oxygen so the computer cuts back on the amount of fuel it's adding to the incoming air. If the sensor output is lower than the target value there is too much oxygen and the computer adds fuel.

Even as fast as all this happens, it's always at least one combustion cycle behind since it's measuring what has already happened. It is compensating for the future and checking its results. Over time the average will be the target value programmed into the computer if everything is working correctly.

Is that what you were talking about?

 

Yes it is - thank you. I would really like to understand how the Harley ECM derives its values and how long it takes to formulate the average and how that applies to VE in open loop. It is my understanding that adaptive fuel applies to open loop only but even if it applies to closed loop I would like to know more about how the calculations are derived.

Why do I want to know this - well I am looking at my data files and I see new VE values in open loop operation and would like to know what the impact of adaptive fuel has on them. I would also like to know if it is a running average or it keeps say only the last 50 miles or so as the baseline.

 

The term "adaptive fuel" is new to me. Where did you pick this up?

It's my understanding that the stock Delphi ECM does not do anything adaptive in open-loop mode. Those values are merely programmed in. How much fuel at what throttle position at what RPM and at what manifold pressure. That stuff is all hard-coded and only in closed-loop mode does it "adapt" to anything, and at that, the adapted values are not retained between computer power-up sessions.

Again, I'd like to know what your source of information is if you've come to understand differently.

 

Here's some old threads on the subject.

https://www.hdforums.com/m_1401373/tm.htm

https://www.hdforums.com/m_1265353/tm.htm

 

Here is a cached page of where I started reading
http://209.85.165.104/search?q=cache...cd=3&gl=us

(you will probably have to substitute the astericks for vee dash twin forums dot com or search in google for "adaptive fuel" sert and it will come up in cached mode.)

Also, I have read numerous recordings and there are new ve values applied when the engine drops out of closed loop mode. This is not always the same even during the same runs at the same TP, Engine Load , Manifold pressure etc. Something is making a judgement and I am trying to understand how it is doing it. I do not agree that anything is hard coded in where it is the same every time and I have tons of data from my engine to prove it.

Also with the digital tech that the dealer has they have the ability set this value back to zero. Therefore I would believe that something does get retained between sessions otherwise there would not be a need to set it to zero. The source of the digital techn information is me as I had it done to my bike about a week ago. I have put so many maps on my bike I wanted to make sure that I was starting fresh and not contaminating my new adjustments with what was previously stored on the ecm.

Bottom line is I want to understand how it works for 07 because there is a difference on these models on how fuel is adjusted. I also have no doubt that there is a bug in the calculations somewhere that some pipe air cleaner combinations can't be tuned for in the normal manner.

 

Tick Tock, your last statement about not working for certain combo's is exactly how I feel, I ran my 07 open loop for a short time and then put about 5500 miles on closed loop, ran good, but tuned open loop it runs great, and much cooler. Don't know how suited the 07 ecm really is for performance use, but then again, it was not intended to be a performance system, it was meant to be epa friendly and do a good job of running a stock bike although I'm not sure it does that either.

 

Here is what Mike from Latus had to say about adaptive fuel and fuel injectors shutting down:

"The injector off times are governed by a table, or other method, that is not accessable via SERT. The AFV is a shift in the VE tables that allows a certain amount of "memory" to occure based on corrections required by the O2's. I.E., if the O2's are constantly shifting to the rich side the majority of time, then the computer will shift the entire VE table that direction by up to 10%. This shift will then be saved thereby reducing the amount the O2's have to shift on a constant basis and when the ignition is cycled. O2 corrections only occure in real time and do not permanently change VE values and so these corrections take a certain amount of time to "catch up" each time the key is cycled. This may not be an entirely accurate description of the actual method used but is the basic philosophy. This is why the AFV should be reset to 100% prior to tuning, otherwise the tuning values will be incorrect by the amount of AFV shift should it be reset at some later time. This can only be done via digital technician, at this time. "

 

Now that is an explanation that makes sense, I could see that if this is truly the case how different builds could be affected and be difficult to tune. What may be a good correction at cruise speeds when applied accross the board may not be what is best for other throttle positions.

 

I agree and this is what I am beginning to find out on mine. There really is no room for a half-*** dyno tune on some combinations. The numbers have to be smoother between rpm and throttle positions except in the power ranges. One thing I have noticed is that tuners only adjust the numbers they are working with for each throttle combination and tend to leave the numbers they believe will never be hit alone. The only problem with this is that the ECM seems to be blending to some degree. For instance you can't hit 3500 rpm at 2% (so this is left alone) but you can hit it 10% (this gets tuned). So without looking at the map as a whole we get into trouble on the 07's. That's what I am thinking at the moment anyway (subject to change by anyone smarter than me giving me a new thing to consider).