gta_88_kicks

Ok, ive got two quick questions.

Does increasing the scalar increase the amount of gm/sec a given maf voltage is, or the opposite? ( I understand i only need to change the scalar at the top of the maf tables)

When I run the scan tool, the raw maf data does not come as volts, is it gm/sec? If so, I would see lets say, 28 gm/sec and a blm of 120. Looking at the maf table #2, 28 gm/sec is 1.65 volts. If i change the gm/sec at 1.65 volts to like 32 gm/sec, would the engine add fuel there?

This is a hypothetical situation, I have only edited constants and flags so far(well no flags needed to be changed).

Grumpy

Yes, that's the concept.

gta_88_kicks

wow thanks thats what ive been thinking, but i needed some reassurance.

1 more question:

i used the formula: (table value/256) times the scalar = voltage

for a lot of the different table values, and the only one that works out is the highest table one value, why is that? (scalar of 17)


volts | gm/sec
--------------------
1.46 | 22.27
1.28 | 17.69
1.10 | 13.92
.91 | 10.87
.73 | 8.35
.55 | 6.20
.37 | 4.49
.18 | 3.23
.00 | 8.35

gta_88_kicks

wait i just made a huge mistake

my scalars are in hex format, so a scalar of 17 hex --> decimal is 23. that would also be why the top of the table is 22.27, really close to the max that table can have.

also tunerpro automatically converts the hex value into what the actual gm/sec the computer sends.

example of what i mean:

the table above in hex format is

volts | gm/sec
--------------------
1.46 | f8
1.28 | c5
1.10 | 9b
.91 | 79
.73 | 5d
.55 | 45
.37 | 32
.18 | 24
.00 | 5d

using the scalar formula for lets say .91 volts i get

121(or 79 in hex) / 256 times 23(17 in hex) = 10.87

the calculated value above!!

i feel really smart right now even though im probably really late with all these discoveries haha

gta_88_kicks

Now there is still a problem. When i change the scalar for table one to 18, the values dont recalculate, they stay as if the scalar was still 17? whats happening?

gta_88_kicks

?

Grumpy

When I do MAF table stuff, I do it with a hex editor.

gta_88_kicks

how do you do that?

i opened up the hex editor in tuner pro but i dont have a clue what it does.

edit - wait actually i do kno what it does, cuz i looked at the start address, and found the table one scalar value in the hex editor. Even though i changed the value in the hex editor, tunerpro still did not recalculate the values, should i just trust that whn i increase the scalars, the maf tables values really are changing? (Well not the values, but the calculated airflow)

another edit - i also see that i can change the voltage values when i open up the ecu item editor, should this be done?

Mangus

tunerpro does not use the scalars for displaying the maf tables, as the ECU format doesn't allow this.

Its my understanding that you don't generally have to touch the scalars unless you're going to change the last value in the table. I've only lightly edited the maf tables in attempts to "Screw around", so I'm not very confident in it yet, but there are a number of good posts on how to do it on this board.

Grumpy

Don't be messing with the scalers until your really clear on what your doing.

Try just looking at what your BL's are at idle.
Then find that location in your MAF tables.
Then make a 10% change in that area, and then look at your BL at idle.

gta_88_kicks

thanks for responding, ive been reading a ton, and found out that you have to change the source code in the ecu file if you want to have more than 23 gm/sec in table 1. I don't have any serious mods like a cam or heads yet, so i don't think ill worry about that till later.

In the hack of a $32 ecu i saw that the gm/sec values come from counts and such. Im gonna do some more reading and learn how to change that type of stuff without screwing everything up.

doc

OK, this is the stuff that I needed help on before.

I have TunerCat. I have a 165 ECM and the 32b definition file.

With the above, how to I change the scalar for each of the 6 MAF tables? Where do I find this scalar?

I need to increase all values and when I tried this, the last value in each table was limited to some value. I need values which are slightly greater than this limitation.

So, can I do this using TunerCat?

EDIT: For example, MAF table 1 is limited to 23.0 in the 512 count cell, and MAF table 2 is limited to 47.8...

gta_88_kicks

the 32b bin file doesn't have a constant for maf scalars that you can adjust in tunercat or tunerpro or whichever software you use.

You can however, look at the 32b hack by that ecmguy dude, and look at the maf tables and youll see where in the code the scalar is. you can adjust it at the source code level, but you need a code dissassmbler and stuff, which i have no idea how to use yet.

the limitation of 23 in table one does not have to do with the maf table scalars, this is a limit set in source code that you also have to change.

i am not 100% sure on this, but maybe grumpy or someone else can verify it.

Grumpy

Changing the SCALER, changes that whole table's, readings.

Lets just for a moment look at an imaginery MAF set-up

Table 1
scaler of 15

Table values of: 64, 128, 255

Table 2
scaler of 45
85, 190, 255
Table 3
scaler of 255
45, 190, 255

The regions of air flow would be (assuming a last table entry of 255).
Table 1, 4-15 gm sec
Table 2, 15-45
Table 3, 45-255

Notice how the last of one table matches the first entry of the next table?.
So when you change a scaler you effect the tables on either side of the one your looking at.

There are all sorts of number games you can play the scaler also sets the resolution of the entries.

ie
Table 1
scaler of 255
4, 7, 15

Table 2
scaler of 255
15, 37, 45

Table 255
45, 190, 255

This would be very similiar to the first set of tables, but the resolution would suffer, since each entry value represents so much.

Make little changes, take notes, and go slow until you really master what your doing.

Doing MAF CORRECTLY takes some time to master.

RBob

iTrader: (1)

See this post starting about halfway down. All the math explained:

https://www.thirdgen.org/techbb2/sho...MAF+AND+scalar

RBob.

doc

Thanks to all above.

The link is alot of reading, it will take me a long time to digest it all. I guess that I will have to learn a new computer language. I have been writing Fortran programs for 35 years, so maybe I will be able to pick it up.

gta_88_kicks

quick question,

If i change the scalar for table 1, can i get the table to have a value higher than 23 gm/sec? Even thoughthe hack of the source code says thats what the max is?

heres what it says the max gm/sec in the hack:

******************************************************
* Mass Air Flow Tables & Param's
*
* DIGITAL MASS FLOW SENSOR
*
* Freq range 34 - 150 hZ
* Period 927 - 437 counts
* Range 1490 counts
*
* table 1 0 - 511 counts, 0 - 22 gms/sec
* table 2 512 - 767 counts, 22 - 48
* table 3 768 - 1023 counts, 48 - 82
* table 4 1024 - 1279 counts, 82 - 135
* table 5 1280 - 1535 counts, 135 - 206
* table 6 1536 - 1791 counts, 206 - 255
*
*
*******************************************************

Grumpy

You can set it to 255. But obviously you won't read that high there. Reexamining my last post should make it clear.

No the hac doesn't say what the max is, it tells you what the current values are. The max entry however is 255.

And the gm/sec rating, loses being accurate once you change anything in the system.

gta_88_kicks

thanks grumpy, mangus, and rbob, and doc, I really appreciate it.

Now that i have a good understanding of whats goin on, i will try to help others as well, this stuff was really confusing at first but u guys made it a lot easier.

Twilightoptics

I've never had to change the scaler, nor have I ever seen a scaler for the MAF.

if you edit the proper gm/sec value in small incriments and observe the changes you can get a pretty good feel for what you need to change and when.

My question is, the $6E ECU has a table: Maximum Airflow vs RPM

What does this table actually accomplish? For instance, my table is set and something from an Ed Wright chip where my MAX 255 value is from 3600rpm on.

While the stock doesn't MAX 255 until the last cell of the table.

While comparing my friends stock maf max values on his 383miniram, and my altered ones with 350hsr..... I see the max maf at 3600rpm at WOT.... while scanning the 383 it wont show the max until the last cell of about 6000rpm.

What's the deal?

RBob

iTrader: (1)

Each of the six MAF tables has a scalar term for that table. If you ever change the last entry of a MAF table and need more airflow then the value of 255 gives you, you will need to change the scalar for that table. Then to do it properly you will need to change the first entry of the next table.

It may be worthwhile to vist the thread I posted up a couple (on this thread). It explains all of this.

The max airflow vs RPM table limits the maximum airflow at that RPM as used by the fueling routines. Apparently Ed knows what he is doing.

RBob.

11sORbust

I would think ED did things wrong. From what I understand, the max airflow vs rpm table is what the aldl will see(if you exceed the table at xgr/sec. So the maf is maxed at 3600 but the aldl reports what's in that table from 3600rpm and up. Wouldn't it be better to report the actual gr/sec considering that rbob stated the table is a part of the fueling routine.? From what I have learned it's not good to lie to the ecm.


The maf scalars is another thing. I think there is no reason to ever change them. Unless you change the I.D. of the meter.

gta_88_kicks

grumpy said a couple posts up that if you change the max airflow at rpm too high you'll lose resolution in those areas, it should only be changed if your motor flows more air at those rpms than the ecm "says it can read?" (lack of good term).

RBob

iTrader: (1)

Oh my, are you guys are conspiring to drive me crazy? :O

The ALDL stream outputs 2 (two!) gms/sec airflow readings. One is the unlimited (as the MAF reads it) value. The other value is the airflow as limited by the airflow vs RPM table. Question is: which one is the scan tool displaying. This is why guys with honking 383's and 406's say that they aren't max'ing the MAF.

"But my scan tool says". . . The scan tool is displaying the limited airflow value, not what the MAF is really reading.

On top of that, the injector PW routine (fueling) uses the limited airflow value. So leaving the max airflow vs RPM table stock on a modified or bigger then stock engine is asking for trouble.

(11sORbust: rbob & RBob is the same guy).

gta_88_kicks, I think that you are confusing the max airflow scalar for each table with the max aairflow vs RPM table. Two different things.

With the MAF scalar tables the last value in each table should be close to 255. This will give the greatest amount of resolution for that table.

RBob.

11sORbust

My maf never maxed on my 406,or so I thought . I know the aldl was displaying the table entries once my actual gr/sec exceeded the tables. I was using winaldl and the slow baude rate, if that matters. My question is... how is the max air flow table connected to fuel calculations?

RBob

iTrader: (1)

Please Tim, didn't I just type this: "On top of that, the injector PW routine (fueling) uses the limited airflow value."

RBob.

Grumpy

Yes, there are reasons, but not before having a total understanding of what your doing, IMO.

A hint would be what PE adders your using for the TPS and RPM, and injector sizing.

Grumpy

????
I said changing the scalers can cost resolution.

It looks like your blurring several items together.

Grumpy

Dunno about the other guys, but I've been giving it my best shot. Heck even Doc stays up late trying to figure out how to stump RBob.

11sORbust

LOL, yes I recall that statement. I was wondering how/when it's used for fuel calculation.

Thanks!

11sORbust

Ok, you cought me on that one. I guess "no reason ever" was too strong.

Twilightoptics

You can't change the scaler term in tunerpro.

It's beyond me, and thus sounds like there is no point.
Here are the ed wright vs stock max air flow.

Then a datalog of a wot run.

funstick

Well im gonna chime in here since nobody seems to wnt to listen. leave the table scalars alone unless youve dicked with your maf sneosr.

Lets look at the basics. WTF is a maf table

its a declarative state ment sayig x voltage equlas x flow. its a transfer function. Unless you took out your screens added a big *** elbow and in general cuased all sorts of chaos leave the maf tables stock your problem does not lie therin.

thing that create trouble. insufficent pe fuel. AE fuel and to much damn spark top the list


Other problems i see. yes the max airflow vs rpm table max every entry to 255 and leave it there.

also log your maf voltage. if your gonna modify your maf table you need to know what cell in the maf table you in to adjust the corresponding valuve.

of lets go back to basics


maf creates 1 volts for 20gram/sec of airflow ( this is at the sensor.

20grm/sec flow into and out of the sneors and it reports 1 volts

ok now the maf holds a line hgh and the ecm pull it to gorund creating a 1 volt signal to the ecm.

the ecm then takes that 1 volt signal and turns it into a a/d count. analog to digital.

so now weve turned the analgod voltage signal into a digital signal or binary bvalue like $20 that the ecm understands


Now the ecm stores that value in the ram.

i then does its other loop and says ok this cycle i have to look up the ram value for MAf ( buried in teh source code btw ) and it load that values. it say ok the maf input is $20.

so it goes to the 2d maf tables and then looks up the approioate cell fo $20 value in from the maf.

If the $20 or say 1280 counts value in the cell is 88grs/sec then it does its BPW and PW calucs based on that value in the table

there is no magic invovled. its just taking dtaa and converitng it into something else.

thats it thats the jist. now leave that maf sensor alone !work on your a/e and your pe settings.

Twilightoptics

Here is a log showing when the maf maxes on a WOT run.

The reading MAF RATE is given per whatever Craig Moates put for his ECM852.exe software on a 165ECM $6E

I have to think that if the maf maxes, you would have to add PE in an exponential rate because of the flatline?

There are ways to overcome this "limitation" if you can measure the guess work with a WB?

Twilightoptics

So you're saying to max every entry, and in doing so..... the ecm will allow the maf to read that high for every rpm?

If that's the case, what is the point of limiting what the ecm thinks the air is anyhow, if the MAF reads the amount of air, then it reads the amount of air?!


And you can't just leave the maf tables alone.... ? Otherwise you have to "tune by injector constant" which doesn't work. 24lbinj constant = pegged 108 for me... At the FP that the injectors ARE 24lbers.

RBob

iTrader: (1)

In the simplest terms the code calculates the required fuel for the commanded AFR with the MAF (max limited) airflow value.

By limiting the reported airflow value the ECM is also limiting the fuel. This is the part of which I don't know why GM implimented a max airflow table. Maybe it was to cover for a bad MAF, one that is mis-reporting the airflow.

In the fueling calculation the code uses the airflow value, the injector constant along with the commanded AFR and comes up with an injector PW. I haven't studied that portion of the code in enough detail to present the inner workings.

RBob.

RBob

iTrader: (1)

Sure is max'ing out, starting right about 4k RPM. I can see what you area saying about the 8.53 ms PW too. Flat as a pancake. Seems odd as I would expect it to change a little. Almost like there is a limiter on the PW term itself. Then the 9.xx PW right in the middle.

Staying with the MAF, and as you mention, adding additional fuel via PE mode does work.

RBob.

funstick

well maybe ill gt off my *** and put up the schematics for the ford to gm line converter ive been using for a while. you will absoulutely have to do something with the maf tables and the lv8 scalar then. along with lying about the injectors size. but as long as you are truthful about the lv8 readings to the ecm everything seems to be happy.

Yeah maxing out every entry in the max airflow vs rpm table seems to cure alot of low end ills. if you also add a ton of PE thats a good way to mask the problem. still a bigger issue is. once your out of maf sensor your running blind. so find a bigger maf sensor and email me. Ill exlpain how to build that converter.

Grumpy

Somethings looks fubar'd to me.
You go to 255 Gm/Sec before the TPS goes up, and then it stays at 255 for a while and then drops, all the while the PWs stay the same.

This is one of those times, an ecm bench would save beating on the car to see what's going on.

If your running a high PE adder you should be going static on the PWs, and your not.

Might try throwing a MAF and or ECM at it, if all the mechanical stuff is correct.

RBob

iTrader: (1)

I think it just dawned on me as to why there is a max airflow vs RPM limit. This also fits in with what funstick mentions in his post above.

When the throttle is wacked wide open from a low thottle angle there is going to be an inrush of air to fill the intake manifold. On a dry flow manifold there is no need to add fuel in the same proportion.

To do so would be like adding a ton of AE. This is turn would cause an excessively rich mixture. It may also be why the MAF signal is filtered via a sliding average. Not to remove noise, but to match the MAF airflow respose to manifold filling/emptying flow. Hmm. . .

RBob.

Grumpy

What for exhaust system are you running, and how healthy of engine?.
Cat Converter?

Grumpy

There are times when it's handy to play with the scalers.

Once the MAF is pegged, your in Alpha-N mode. It's a GMese version but your AFR corrections are % changes, by RPM, vs TPS. Crude at best but that's how it's designed. If you want to shift the PE tuning to use the RPM correction differently they you'll want to limit the PW calculation from the MAF toward the RPM side of the equation. The only way to increase the amount of PE that you can add by RPM is limiting what the MAF contribution is.

And in certain applications, there are other tricks, but you have to be familiar with how it all works, and that first means figuring out the basics. If you want to get to the trick stuff then you have to get a ecm bench, a WB, and see what's truely going on.

11sORbust

Wouldn't it take one hellofa engine for that to happen?

Twilightoptics

No cat, 2 1/2" on each bank into a single 3". Straight back to a 3" flowmaster with dual 3" outs.

Two runs on the dyno yielded the same afr, as the third run on the dyno when I opened my cutout (was only a hair leaner with cutout open). However, I did gain 12HP and 15lb ft with the cutout open.

The engine has 9000mi on it. I can't garuntee the rings are firmly seated (chromemoly) but my oil consumption is low if any, and my plugs all show the same.

The MAF is a wells SU145 maf. Worked great since I put it on, the relays are 6 months old.

ECM is stock. (friend might be buying a new one and I will try swappin them to see if there is a change).

Its not like this is an intermittant problem, it's the same each time.

Twilightoptics

Anyone see a limiting constant/table?

Twilightoptics

errr

funstick

the reason there is so much sliding averaging happening is becuase the damn airbox create a ton of noise. Im ot scanning up the info ive gained via a maf calibration stnad but typical noise is in the 2.7% range.

the air limiting table is there to keep people from modding there engines. From the mouth of a gm durabilty engieneer. trust me its bs but they did it.

there is also one other reason fr that table. If the maf goes south and the bosch mafs have a 60% failure rate then it keeps the ecm from over fueling. to much drive current on the sensors op amp was the primary culprit.

Anywas thats about all ive got to say on the subject.

funstick

in all reality there should be no need to touch the maf scalars unless 2 things have happened.


1. youve decreened or ported the maf. are using a non stock maf or a larger maf. you would only need to touch the maf tables and scalars if the linearity and curve of the maf sensor it self had been changed.

2. youve done something fiarly significant to the sensor routing. with a typical gm screened maf air ducting isnt a big deal. but if you use a descreened sensor then wow your in for one hell of ride.

yeah the scalars need to be tweaked once in a great while. best way to aviod having to touch the maf tables is by keeping 12-14 inchs of stright tubbing in front of and behind the maf if you take the screens out. also if you take the creen out youve created a **** load of noise becuase the stock intake ducting is damn noisy in terms of air flow distrubance.

anyways im done ranting for today.

Twilightoptics

The new $6E mask, version 11... has provisions for the maf scalars! And it works in Tuner pro!

Grumpy

So reversion plays no role?.
It does in my world.