SERT Self Tuning question
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Road Master
Joined: Mar 2007
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SERT Self Tuning question
If you were to the entire center of the map a VE of say 90. Then put the bike on the dyno and data log it, you will get a output of VeNew of say 95. Now you go drive the bike for 500 miles. If you put the bike back on the dyno and retest, Will you get backthat the VE still 90 and the VeNew is still 93 or will you find that the stock ECU self learn has moved the VE closer to the 95 number and VeNew is still 95?
Note that this question only applies to 02 equiped bikes.
AW
Note that this question only applies to 02 equiped bikes.
AW
Outstanding HDF Member
Joined: May 2007
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From: Florida
RE: SERT Self Tuning question
The number would be what ever it took to get your desired AFR using up to 40%of the mas map....if it took more than 40% of the base map and you still havent reached your desired AFR a code will be thrown.
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Road Master
Joined: Mar 2007
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RE: SERT Self Tuning question
Doc 1
At one point I heard there was something known as the "adaptive fuel table" that had a +/- 20% limit and now there is a 40% and a "mas table"? I am still confused how this all relates to the numbers reported in the data log as "Ve New" and "02 integrater"
The math appears to be
ve new / ve = o2 integrater is normally close but is never quite correct.It can be as much as 4% incorrect but most of the time is withing 2%. Is there something else in the math? Is this a programming error in the data logging software.
This all appears to be new for the 02 bikes.
AW
At one point I heard there was something known as the "adaptive fuel table" that had a +/- 20% limit and now there is a 40% and a "mas table"? I am still confused how this all relates to the numbers reported in the data log as "Ve New" and "02 integrater"
The math appears to be
ve new / ve = o2 integrater is normally close but is never quite correct.It can be as much as 4% incorrect but most of the time is withing 2%. Is there something else in the math? Is this a programming error in the data logging software.
This all appears to be new for the 02 bikes.
AW
Outstanding HDF Member
Joined: May 2007
Posts: 2,304
Likes: 31
From: Florida
RE: SERT Self Tuning question
The ADF will add 10% to the base map but don't forget the 02 sensors can and will addor subtract up to 30% .So take the 02 sensors 30% and add another 10% from the AFV and there you have the 40%
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Road Master
Joined: Mar 2007
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RE: SERT Self Tuning question
If you have a stock ECU/factory tune and change the pipe or intake, the stockECU will attempt to tune itself. Lets assume after a few hundred miles, the stock ECU gets close to a good tune but not perfect. If you hook up a SERT and data log the output, will the outputsinclude VeNew and Timing/Knock Retardthat you can use to create a first best guess for your SERT tune?
AW
AW
HD EFI Guru
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RE: SERT Self Tuning question
You all need to remember how the system learns and how it applies what it learns are not the same thing. Since there are only so many cells for learn data they cover many VE points each, so which VE point was the one the ECM used to learn from? VE is air filling and has nothing to do with fuel mixture itself. Its used to calculate the fuel mixture so you can lie to the VE to get a predicted result just as you can lie about the injector size or engine displacement to get a predicted result.
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Road Master
Joined: Mar 2007
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RE: SERT Self Tuning question
Steve, thanks for your reply. As I understand the SERT basic math, the pulsewidth is made up from...
A constent developed from the injector size and engine displacement)
X
(AFV) ... this is a slowly moving +/- 10% correction that can't be reset with SERT software
X
(Adaptive Fuel Tables VE Lookup) ... a multi celled table (of unknown size ofXby Y and tied to either MAP or TPS and RPM)developed on what the ECU learns from the O2 in closed loop only and cleared on reflash. Only seen in data logsas VE new. This is reset with a reflash.
X
(Main fuel tables VE Lookup) ... Based on the main VE table.
X
(MAP reading in KPA/100) ... This is almost never talked about but is apparently there looking at the VE values and that the system is claimed to be a speed density system. The VE table is Alpha-N presentation. Strangly the AFR targets and the timing tables are MAP based.
X
(Acceleration or Decel enrichment correction) ... only when acceleration is triggered and this trigger point is not adjustable but the amount is adjustable
X
(Warmup fuel correction)
X
(The desired AFR)... This is verified when in closed loop. This is adjusted by moving the AFV and the Adaptive Fuel Tables
* * * * * * * * * * * * * * * * * * * * * * * * * * * *
If the above is all true then doesn't each and every term have a direct effect on the actual final AFR? Sorry if I keep rewording the same questions but I am still trying to get my head around the underlying software logic.
AW
A constent developed from the injector size and engine displacement)
X
(AFV) ... this is a slowly moving +/- 10% correction that can't be reset with SERT software
X
(Adaptive Fuel Tables VE Lookup) ... a multi celled table (of unknown size ofXby Y and tied to either MAP or TPS and RPM)developed on what the ECU learns from the O2 in closed loop only and cleared on reflash. Only seen in data logsas VE new. This is reset with a reflash.
X
(Main fuel tables VE Lookup) ... Based on the main VE table.
X
(MAP reading in KPA/100) ... This is almost never talked about but is apparently there looking at the VE values and that the system is claimed to be a speed density system. The VE table is Alpha-N presentation. Strangly the AFR targets and the timing tables are MAP based.
X
(Acceleration or Decel enrichment correction) ... only when acceleration is triggered and this trigger point is not adjustable but the amount is adjustable
X
(Warmup fuel correction)
X
(The desired AFR)... This is verified when in closed loop. This is adjusted by moving the AFV and the Adaptive Fuel Tables
* * * * * * * * * * * * * * * * * * * * * * * * * * * *
If the above is all true then doesn't each and every term have a direct effect on the actual final AFR? Sorry if I keep rewording the same questions but I am still trying to get my head around the underlying software logic.
AW
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RE: SERT Self Tuning question
The VE table is not Alpha-N. It simply uses TPS and RPM as it's break points. Alpha-N is a TPS and RPM based fuel control and the Delphi unit is not. VE is the amount of air entering the cylinder under a given condition, no more no less. The VE term is use to calculate the amount of fuel to be added but VE is still just the amount of air.
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Thread Starter
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Road Master
Joined: Mar 2007
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Likes: 23
RE: SERT Self Tuning question
What I said was "The VE table is Alpha-N presentation" The code is reallyis speed densitycode.
The differance between alpha-a and speed density is that speed densityhas the very dynamic intake manifold MAP reading included as a primary terminthe basicfuel calc. In most of the other versions speed density the VE correction is based on a table (RPM,MAP) as air flow past the intake valve is a far better fuction of intake MAP than it is a fuction of throttle position. Harley for some reason chose (RPM,TPS) andnow we have to live with it. With true Alpha-N,MAP in the intake is ignored. In a few versions of EFI, a MAP sensor reads ambient air pressure and uses that for an estimatedexhaust backpressure and or intake air pressure correction as altitude changes. Playing with all this stuff over at Megasquirt are all just options in the softwareand not inhearent limits of the software.
Over there, it is almost manditory to learn EFI theory before learning EFI tuning. Most noobee questions are answered with "read the manual, page xxx" The megamanual is one of the best general EFI manuals in the industry. I kept it a bathroom reading for almost a year wile the Megasquirt software evolved into one of the most powerfull EFI softwares offered anywhere.
AW
The differance between alpha-a and speed density is that speed densityhas the very dynamic intake manifold MAP reading included as a primary terminthe basicfuel calc. In most of the other versions speed density the VE correction is based on a table (RPM,MAP) as air flow past the intake valve is a far better fuction of intake MAP than it is a fuction of throttle position. Harley for some reason chose (RPM,TPS) andnow we have to live with it. With true Alpha-N,MAP in the intake is ignored. In a few versions of EFI, a MAP sensor reads ambient air pressure and uses that for an estimatedexhaust backpressure and or intake air pressure correction as altitude changes. Playing with all this stuff over at Megasquirt are all just options in the softwareand not inhearent limits of the software.
Over there, it is almost manditory to learn EFI theory before learning EFI tuning. Most noobee questions are answered with "read the manual, page xxx" The megamanual is one of the best general EFI manuals in the industry. I kept it a bathroom reading for almost a year wile the Megasquirt software evolved into one of the most powerfull EFI softwares offered anywhere.
AW
Thread Starter
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Road Master
Joined: Mar 2007
Posts: 1,177
Likes: 23
RE: SERT Self Tuning question
VE is really a correction for airflow ability of the motor that is notpredicted (or as a function of)by the MAP alone. This can be due to intake reversion, resonance, strange airflow around the intake valve and throttle body, vorticies in the air flow in the air filter, poorly designed muffler and all sorts of other things. This is why changing anything in the intake series can mess with the VE tables.
Normally all these flows are designed to be near perfect at mid RPM and full throttle and this is why most motors have near 100% VE in that section of the fuel maps. At low RPM the throttle angle and the air trying to get thru that very small hole pulls the VE way down. At high RPM its the exhaust, camand heads that normally get in the way of huge air flow. Air filter and throttle body sizing issues holding back HP are seen in the MAP reading movig away from 100 KPA at WOT. I have seen this ignored in several data logs in the Harley world. In the Rice world, this is everything.
See http://www.ncs-stl.com/fuel/ReqInjectors03.xlsfor how the math works. The yellow cells are unprotected. The air velosity thru the intake is very important if HP is the real goal. I like to design to max air velosity in the intake at below 60 MPH A GSXR is in the 40 MPH range with its 4 45mm intake ports. Excessive throttle response off idle is the down side.
Here is a link to a small part of the megamanual that deals with this stuff
http://www.megamanual.com/v22manual/mfuel.htm#equation
Hope this helps
AW
Normally all these flows are designed to be near perfect at mid RPM and full throttle and this is why most motors have near 100% VE in that section of the fuel maps. At low RPM the throttle angle and the air trying to get thru that very small hole pulls the VE way down. At high RPM its the exhaust, camand heads that normally get in the way of huge air flow. Air filter and throttle body sizing issues holding back HP are seen in the MAP reading movig away from 100 KPA at WOT. I have seen this ignored in several data logs in the Harley world. In the Rice world, this is everything.
See http://www.ncs-stl.com/fuel/ReqInjectors03.xlsfor how the math works. The yellow cells are unprotected. The air velosity thru the intake is very important if HP is the real goal. I like to design to max air velosity in the intake at below 60 MPH A GSXR is in the 40 MPH range with its 4 45mm intake ports. Excessive throttle response off idle is the down side.
Here is a link to a small part of the megamanual that deals with this stuff
http://www.megamanual.com/v22manual/mfuel.htm#equation
Hope this helps
AW