SERT, What is it? Get your answers here !!

[whittlebeast]

Originally Posted by kelly

Doc--so would that "wall" dipicted on whittlebeast's graph be a characteristic of a quick roll off the throttle then?

I am suspect that this is a way do add additional (synthetic) AE for quick throttle stabs when at idle. In the remote chance someone really does go full throttle at those RPMs the motor may go butt rich if left there. Most pipes that will pull to high RPM tend to have horible scavanging at low RPM that would create anywhare this much fuel at that RPM. Generally, AE requirements are huge down there compared to on top.

I wrote the following as a FYI over at Magasquirt a wile back. Some of the terminology is a little different on the SERT but the concepts are all the same.

from http://www.msextra.com/viewtopic.php?t=16087

Hope this helps

AW

<<< snip >>>

There is a lot of confusion regarding the tuning of Acceleration Enrichment in the MegaSquirt family of programs. Over the last two years I have been involved, to a varying degree, in several of these ways to control AE. It is far easier to tune AE if you under the underling causes and effects.

There are a few that we have to consider. (Hang with me here)

1) You may remember from high school physics that water will boil at close to room temperature if you pull enough vacuum on it. Conversely, if you apply pressure you can raise the boiling temp up to 250F or more.

2) Water on the driveway always evaporated faster on a windy day than it does on a calm day.

3) Water on the driveway always evaporated faster on a hot day than it does on a cool day.

4) If you leave a cold glass of beer on the counter water droplets form on the side of the glass, apparently water from nowhere.

5) Cold air has more oxygen molecules per cubic foot that hot air.

6) A VE table as we in the MegaSquirt world is designed to balance the amount of fuel delivered from the injectors with the air flow. The internal math of the MegaSquirt estimates this airflow and in turn calculates the matching injector pulse width. This airflow calculation is based on intake air temperature, RPM, intake manifold absolute pressure (KPA), and RPM.

7) An intake manifold often has hot water in it. This manifold is attached to hot things and is being blown on by constantly changing amounts of hot air coming off of the radiator and from the exhaust system.

8 ) An intake manifold has a constantly changing amount of air properties and the amount of fuel that can condense on the walls.

9) Fuel in the intake constantly collects on the inside walls of the intake.

10) The amount (thickness) of this layer of fuel is constantly changing.

11) The earlier the fuel is injected in the intake airflow, the more area of the intake wall can get wet.

12) Back pressure on the exhaust, weather caused buy high atmospheric pressure at the end of the exhaust system or by trying to flow too much exhaust through the system causes the motor to need less fuel.

13) The injector delivers fuel only after it has opened. The injector opening time consists of about the first 1.0 millisecond of the pulse width. So if MT reports 10 ms pw1 the injector is only supplying fuel for about 9 ms. This is a big deal if you have a cruse pw of say 4ms and your AE added pw is 6ms. The amount of fuel delivered goes from (4-1) or 3ms of fuel to (4-1)+6 or 9ms or three times the fuel. Plenty of fuel to put out the fire.

14) Way too much fuel feels just like way too little fuel from the driver’s seat.

15) Fuel collecting in the walls and floor of the intake behaves much like the water examples above.

[HDMD88]

Originally Posted by kelly

Doc--so would that "wall" dipicted on whittlebeast's graph be a characteristic of a quick roll off the throttle then?

No this graph isn't what you would think of as a dyno run......it is air movement at rpm to throttle position relation.

[GPO03FatBoy]

Originally Posted by whittlebeast

I am suspect .....
I wrote the following as a FYI over at Magasquirt ...

Mega what? For a second there I thought it was April 1st! now back to thoughts about the SERT....

[kelly]

Doc--I was thinking of a dynometer, just not one that uses a drum/wheel relationship.

Whittlebeast--I think I'm tracking on your thought about the amount of VE at slightly ABOVE the idle. Here's my thought on why that wall is there--the bike is already moving and most operators instictively go to 0% throttle during shift (not all, but most street riders). Can't really compare an autos drop in RPMS (800) to a 2 cylinder motor while shifting as most street riders drop about 1500RPMs before they get the scooter shifted (about .4 to .8 of a second the motor decels).

Now, there are many exceptions on this forum--heck, Tote and Taz GAIN 800RPMs on the shift when they pilot down the 1/4 (one of these days you will find that stronger clutch plate fellas---one day--second thought you both are thrashing transmissions already)!

Whittlebeast, my question to you is, is that graph you posted a result of data collected from the MAP currently in your bike and then if it is, do you experience the decel pop-pop-pop and then a roll on the throttle with hold on acceleration? Just a fleeting thought on my part.

So whittlebeast--ought to be interesting to hear what else you got to say about FI.


Mr. Doc, Mr. GeeeROCK, and Mr. Silverbullet can make a scooter turn 7800rpm just by looking at it--and they make my head hurt with the tech stuff and developments they have done...craftsmen through and through.

[whittlebeast]

That is a standard map right off the SERT CD. I opened twenty or thirty of them just looking for patterns. Remember I am an EFI guy but I am new (about a year) to the Harley world. I did lots of the bleading edge bata tuning for the www.MSEFI.com programmers. I was the first to bring up a 2 stroke 800cc 140hp jetski on EFI running MAF. I love a challange I have sorted thru getting a 2007 Sporty to handle like my Honda ST1300. Now I am taking on the EFI.

This is the 1000 lb winged and Squirted race car I normally work on
http://www.youtube.com/watch?v=ZXH4WWhqZ_s

This is the 8000 RPM Squirted Honda rice car my kid recently sold
http://www.ncs-stl.com/crx/

My racecar is at
http://www.ncs-stl.com/racecar/

AW

[GPO03FatBoy]

Personally I don't pay much attention to the shape of the untuned VE tables. At their best, the VE tables are a depiction of the air flow through the engine (from air filter through exhaust) at all throttle and rpm positions. This generally takes a lot of tuning time to get accurate. Fuel needs are addressed in the AFR table (and supplemented in the warmup, accel, and other tables). The VE tables just characterize air flow to help calibrate the actual fuel delivery to the fuel demanded by the ECM. But uncalibrated the VE tables may - or may not - be close to reality. One would like to think that HD took the time to fully map each motor combination it lists a map for, but.......

[whittlebeast]

Originally Posted by kelly

Whittlebeast--I think I'm tracking on your thought about the amount of VE at slightly ABOVE the idle. Here's my thought on why that wall is there--the bike is already moving and most operators instictively go to 0% throttle during shift (not all, but most street riders). Can't really compare an autos drop in RPMS (800) to a 2 cylinder motor while shifting as most street riders drop about 1500RPMs before they get the scooter shifted (about .4 to .8 of a second the motor decels).

Now, there are many exceptions on this forum--heck, Tote and Taz GAIN 800RPMs on the shift when they pilot down the 1/4 (one of these days you will find that stronger clutch plate fellas---one day--second thought you both are thrashing transmissions already)!

Whittlebeast, my question to you is, is that graph you posted a result of data collected from the MAP currently in your bike and then if it is, do you experience the decel pop-pop-pop and then a roll on the throttle with hold on acceleration? Just a fleeting thought on my part.
....

Most shifts on the street are in the 0-30% throttle and 3500 RPM droping down to 2800 RPM so this "wall" is not even in the normal operating range.

Remember I have a Sporty, so I think of 3500 to 2800 RPM range normal. I would think a big twin would be somewhat less RPM stock. I have never been on a BT with a tach.

AW

[kelly]

talk about putting the cart before the horse...would it be possible then to look at a VE table, adjust it, have the system perform all the algorhythms(sp.)/logic adjust the other tables (timing, afr, etc.)based off the changes from the VE?

[whittlebeast]

Originally Posted by kelly

talk about putting the cart before the horse...would it be possible then to look at a VE table, adjust it, have the system perform all the algorhythms(sp.)/logic adjust the other tables (timing, afr, etc.)based off the changes from the VE?

You have the right idea. You are just getting the wording a little messed up.

AW

[HDMD88]

Originally Posted by kelly

talk about putting the cart before the horse...would it be possible then to look at a VE table, adjust it, have the system perform all the algorhythms(sp.)/logic adjust the other tables (timing, afr, etc.)based off the changes from the VE?

The ONLY adjustment that should me done to the VE table is to Synchronize it to 13.2 on the AFR Table in every column and row (rpm and throttle position) After this is achieved there should be NO more adjustments in the VE table ....except to eliminate popping from the pipe at 0%tp and 2%tp in the 1750 rpms~7000 rpm area. After the VE table is synchronized you set the AFR table back to the original values.....now when you see 14.1 or 13.5 or 12.8 in the AFR table grid that is what your actuality getting, if you alter the VE at this point you will be changing the value of the fuel ratio too.

VE tables have nothing to do with the timing tables. Remember the VE Tables are an indication of air moving through the motor and are used as a look up reference for the ECM to deliver the correct fuel ratio you requested in the AFR Table.

[fc5467]

Springer / HDMD 88 all expert tuners....
If your bike is running a dual exhaust, then each cylinder would need to be calibrated individually correct? If so when the tuner is finished it would only stand to reason I would get two AFR tables front and rear and also two dyno runs, is this correct?

Scenario:
I just had my bike dynoed after doing a 95" build. The numbers I am seeing are much lower than expected and tune is in question. The shop that did the machining and provided the build is very reputable, but not local. He did not assemble or tune. It is a package he provides to many and he knows what I should see for results, ( even with the dual not being the most desireable exhaust) his tuner says the numbers are lower then he would expect.

I don't want to be acusatory to the tuner, just need to be very informed and want ask some intelligent questions which will ultimately reveal what was or wasn't done.

Frank

[HDMD88]

Originally Posted by fc5467

Springer / HDMD 88 all expert tuners....
If your bike is running a dual exhaust, then each cylinder would need to be calibrated individually correct? If so when the tuner is finished it would only stand to reason I would get two AFR tables front and rear and also two dyno runs, is this correct?

Scenario:
I just had my bike dynoed after doing a 95" build. The numbers I am seeing are much lower than expected and tune is in question. The shop that did the machining and provided the build is very reputable, but not local. He did not assemble or tune. It is a package he provides to many and he knows what I should see for results, ( even with the dual not being the most desireable exhaust) his tuner says the numbers are lower then he would expect.

I don't want to be acusatory to the tuner, just need to be very informed and want ask some intelligent questions which will ultimately reveal what was or wasn't done.

Frank

Frank I wouldn't say, or not say, you should have had two graphs...I will say that both cylinders have to be dialed in separately or it's not a good tune. If the tuner/operator did the job correctly there will be evidence of this in the dyno files...I don't see anyone deleting 60 to 100 runs every time he/she tunes a bike. If he/she only made 5 or 6 runs the tune was not done... period.

[fc5467]

Doc,

one afr and one dyno for each cylinder?

[HDMD88]

Originally Posted by fc5467

Doc,

one afr and one dyno for each cylinder?

Yes I know what you mean, all I'm saying is I haven't seen this as a practice from tuners, However if your tuner did the job correct there will be a record of both cylinders fuel lines at all the throttle positions in the dyno computer and he should be able to print it out for you. Actually if you wanted an accurate fuel reading you will have 26 graphs....13 for the front cylinder and 13 for the rear cylinder.
Tell me how many runs did your tuner make? this info will be on your graph in the note area beside your name or it will say "run file _ _ _'' with a triple digit number.

[fc5467]

It says 109 next to run file, hope that helps or tells you something.