How Speed Density works.
- Thread starter TurboBob
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TurboTdr3.8
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Thanks
Pronto
No amount of evidence will ever persuade an idiot.
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Can you recommend any websites or reading material for learning more about tuning a speed density system for someone that has only tuned a regular TT chip? I am intrigued with all this but I also would not want to be overwhelmed with adjustments that I have no understanding of. Will this chip have to be constantly adjusted for varying weather temps or does it have the ability to learn what it needs to do? I understand that the wideband would control the wot a/f so am referring more to the around town no/low boost type of driving.
There is no real "learning" set up in the chip, it runs closed loop all the time with the wideband, not just at WOT. As long as the the tune is close, there are no issues with daily driving.
As far as reading material, there is lots of stuff "out there", but most of it is pretty generic.
Since this system was designed specifically for the Buicks, the base tune should be pretty darn close.
Eric and I will be taking some walk-thru videos which will help.
Bob
As far as reading material, there is lots of stuff "out there", but most of it is pretty generic.
Since this system was designed specifically for the Buicks, the base tune should be pretty darn close.
Eric and I will be taking some walk-thru videos which will help.
Bob
not at the moment, but it is something we may be adding if there is enough interest.
which brings up another point.
In the SD2 system, the majority of the air/fuel calculations are being done by the powerlogger itself, and the results are then passed thru to
the chip which then delivers the fuel. What this means is that features like DFCO could be developed and you would just download the new file into the PL.
Cool, huh.....
Bob
once every 16 ms, it could be done faster but it hasn't been necessary from what we have seen.
Bob
are the closed loop gain settings user adjustable? or do you set that in the backround?
yeah, the thread has drifted from a general Speed Density thread to one more specific to the SD2 chip.
no big deal.
the closed loop gains are preset in the chip and are not currently adjustable. They are set based on erics experience with the previous generation SD chip.
If necessary, we will add some gain adjustments.
Bob
no big deal.
the closed loop gains are preset in the chip and are not currently adjustable. They are set based on erics experience with the previous generation SD chip.
If necessary, we will add some gain adjustments.
Bob
Eric Stage I
TurboTweak Guy
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- May 25, 2001
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- 2,671
The closed loop rate varies with RPM due to lag time (transport lag) or how long it takes air to pump through the engine and hit the O2 sensor. It's slow at idle, fast at high RPM.
It is preset in the backround and not currently changeable by the user.
Closed loop can be disabled temporarily for use with a 2-step, by supplying 12v to unused pin D11 at the ECM.
It is also disabled in the 1psi to 12psi area where boost is typically moving too fast for closed loop to be of any use.
It is preset in the backround and not currently changeable by the user.
Closed loop can be disabled temporarily for use with a 2-step, by supplying 12v to unused pin D11 at the ECM.
It is also disabled in the 1psi to 12psi area where boost is typically moving too fast for closed loop to be of any use.
Hmm, I just realized something. I think I still have a wire hooked inot D11 for the Extender chip. It's hooked to the dash lighting and was used for setting open loop features in the Extenders.
Am I remembering right Bob?? Should I disconnect that wire?
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