Does the FBody learn driving habits?
12-02-2005, 08:29 PM
#1
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Does the FBody learn driving habits? Thought somewhat new to the LS1 world, I have been floating around on Ls1tech for awhile and have been trying to learn as much about my F-Body (01 SS A4) as possible.
Without sounding like a complete idiot, I was wondering if the F-Body's ECU learned driving habits? I baby my SS and can count on one hand the amount of times I've put it to the wood in the last 6 months. If I were to give the car some full-throttle runs more often, would I have a harder running car because the ECU would learn a more aggresive driving habits and in turn advance more timing, reduce torque managmentt, etc.? I also understand that if your car has codes that haven't been cleared that it can pull timing too?
I was having a converstion with a buddy who has an E46 SMG M3 and said he was told by a tech at Beemer that if an M3 was driven easy all the time, that when you punched on it, the car wouldn't pull as hard as a car that was driven harder all the time. He said that it took 3 full-throttle launchs for the ECU to re-learn a more aggresive tune (IE faster, higher shift points and more timing) and that if driven harder more often, that the times you did punch it, it would pull harder.
He's like me and babies his car, but the tech took him out and punched his car from a 1st gear roll, then did 3 WOT runs from stop and then proceeded to do another 1st gear roll from the same speed and my buddy "claims" the car pulled harder and shifted faster after the 3 WOT runs. Do ECU's "learn" driving habits and do this, are F-Bodies the same?
Sorry for the somewhat meat-headed questions.
Thanks
-J-
Without sounding like a complete idiot, I was wondering if the F-Body's ECU learned driving habits? I baby my SS and can count on one hand the amount of times I've put it to the wood in the last 6 months. If I were to give the car some full-throttle runs more often, would I have a harder running car because the ECU would learn a more aggresive driving habits and in turn advance more timing, reduce torque managmentt, etc.? I also understand that if your car has codes that haven't been cleared that it can pull timing too?
I was having a converstion with a buddy who has an E46 SMG M3 and said he was told by a tech at Beemer that if an M3 was driven easy all the time, that when you punched on it, the car wouldn't pull as hard as a car that was driven harder all the time. He said that it took 3 full-throttle launchs for the ECU to re-learn a more aggresive tune (IE faster, higher shift points and more timing) and that if driven harder more often, that the times you did punch it, it would pull harder.
He's like me and babies his car, but the tech took him out and punched his car from a 1st gear roll, then did 3 WOT runs from stop and then proceeded to do another 1st gear roll from the same speed and my buddy "claims" the car pulled harder and shifted faster after the 3 WOT runs. Do ECU's "learn" driving habits and do this, are F-Bodies the same?
Sorry for the somewhat meat-headed questions.
Thanks
-J-
12-02-2005, 08:55 PM
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Fuel trimming, i'll have to do a search on that, thanks. The explains why sometimes like you said it doesn't feel that strong and others it'll get a nice patch shifting into second.
What exactly is fuel trimming?
Thanks
-J-
What exactly is fuel trimming?
Thanks
-J-
12-02-2005, 09:56 PM
#4
this should explain the whole stft/ltft principal as they are derived from a porportional fueling table...
here an article that might help...or it might just confuse the hell out of you...depends on how your mind works...
hope this helps you out
here an article that might help...or it might just confuse the hell out of you...depends on how your mind works...
Originally Posted by Ken on the HPTuners Forum
Proportional fuel’s entire job is to move the AFR up and down slightly. Just enough to go above 14.7 and below 14.7
Proportional fuel is added and subtracted to the base pulse width. It's not an engine tuning value, it’s the beginning of the closed loop learning process. Unlike most PID (proportional integral derivative) controllers, the closed loop fuel is PI only.
Here is a good PID link http://www.expertune.com/tutor.html
The VCM makes the fuel go rich with proportional fuel and looks for the change on the O2 sensors. It counts the time it took to go rich.
Then after that it does the same thing for lean. It’s always switching the fuel back and for to try and “center” it around 14.7
An expired time in the AFR switching results in an STFT correction. Persistent errors result in an LTFT correction
There are three values in the third chart. Left O2, Right O2 and AFR as measured with a Dynojet Wideband Commander.
You can see that the Stock O2 sensors always report around 800 MV for rich and 50 MV for lean.
They Dynojet shows the AFR switching from around 14.6 to 15.2
The stock sensors will report 800mv or 50mv on just about anything above or below 14.7, so they are not a good tool for tuning this.
If your proportional fuel tables were too low, they would not move the fuel far enough to go above or below 14.7
If your proportional fuel tables are too high, they will move the fuel much higher and lower than need be to cross the 14.7 point. This will saturate the O2 sensor signal.
This over correction causes the engine RPM to oscillate slightly as it goes very rich to very lean.
While the proportional tables are a % Base Pulse Width modifier, you need to know the actual Airflow & BPW the engine is using in order to calculate it.
With varying load conditions it’s almost impossible to do by hand. Just log the data and see where things may need a small shift.
You normally don't need to touch these tables unless you have increased your injector size. Be fore warned that increasing the injector size without the use of a vacuum referenced fuel regulator starts to cause problems on some engine combinations.
Guys running large blower cams and forced induction will notice this very quickly. A lot of aftermarket injectors are flow rated at 43 psi while you are running close to 60 psi.
Now when you get into an area where the pulse width is very small, and the injectors cannot fire you wind up with a false lean spot.
The VCM will try to correct for this by making the engine rich. Now the engine is to rich and it will make it lean again to the point where the injectors don’t work. This cycle will repeat resulting in large engine RPM changes and weird looking STFT values.
On extreme cases it feels like a hesitation in the motor during cruise and deceleration.
Good luck and happy tuning,
Ken
Proportional fuel is added and subtracted to the base pulse width. It's not an engine tuning value, it’s the beginning of the closed loop learning process. Unlike most PID (proportional integral derivative) controllers, the closed loop fuel is PI only.
Here is a good PID link http://www.expertune.com/tutor.html
The VCM makes the fuel go rich with proportional fuel and looks for the change on the O2 sensors. It counts the time it took to go rich.
Then after that it does the same thing for lean. It’s always switching the fuel back and for to try and “center” it around 14.7
An expired time in the AFR switching results in an STFT correction. Persistent errors result in an LTFT correction
There are three values in the third chart. Left O2, Right O2 and AFR as measured with a Dynojet Wideband Commander.
You can see that the Stock O2 sensors always report around 800 MV for rich and 50 MV for lean.
They Dynojet shows the AFR switching from around 14.6 to 15.2
The stock sensors will report 800mv or 50mv on just about anything above or below 14.7, so they are not a good tool for tuning this.
If your proportional fuel tables were too low, they would not move the fuel far enough to go above or below 14.7
If your proportional fuel tables are too high, they will move the fuel much higher and lower than need be to cross the 14.7 point. This will saturate the O2 sensor signal.
This over correction causes the engine RPM to oscillate slightly as it goes very rich to very lean.
While the proportional tables are a % Base Pulse Width modifier, you need to know the actual Airflow & BPW the engine is using in order to calculate it.
With varying load conditions it’s almost impossible to do by hand. Just log the data and see where things may need a small shift.
You normally don't need to touch these tables unless you have increased your injector size. Be fore warned that increasing the injector size without the use of a vacuum referenced fuel regulator starts to cause problems on some engine combinations.
Guys running large blower cams and forced induction will notice this very quickly. A lot of aftermarket injectors are flow rated at 43 psi while you are running close to 60 psi.
Now when you get into an area where the pulse width is very small, and the injectors cannot fire you wind up with a false lean spot.
The VCM will try to correct for this by making the engine rich. Now the engine is to rich and it will make it lean again to the point where the injectors don’t work. This cycle will repeat resulting in large engine RPM changes and weird looking STFT values.
On extreme cases it feels like a hesitation in the motor during cruise and deceleration.
Good luck and happy tuning,
Ken
12-03-2005, 12:25 PM
#5
Spark adaptive learning,
fuel trims,
idle adaptive learning,
and Transmission adaptive shift learning.
Learn for every thing going on with the vehicle. If it hasnt learned anything in those areas of more agressive driving, they technically YES, it does learn itself to be more ACCURATE at different levels of driving.
Take the Fuel trims for example. It sets up the tables for the amount of error needed to correct a lean or rich condition and to make the other multiplier tables be closer to the actual commanded ratios, But, if a vehicle has not been in those areas, then it can never learn what it needed to be accurate.
fuel trims,
idle adaptive learning,
and Transmission adaptive shift learning.
Learn for every thing going on with the vehicle. If it hasnt learned anything in those areas of more agressive driving, they technically YES, it does learn itself to be more ACCURATE at different levels of driving.
Take the Fuel trims for example. It sets up the tables for the amount of error needed to correct a lean or rich condition and to make the other multiplier tables be closer to the actual commanded ratios, But, if a vehicle has not been in those areas, then it can never learn what it needed to be accurate.
