Target A/F Closed Loop Correction Limits

[oldtimer]

Can someone clarify for me which rows out of 1 thru 8 and Top Row are they referring too.

At first I thought it was pretty simple, then I started to see that there are 17 rows across ( horizontal, 0 - 7500 rpm ) and "16" rows vertical. ( 1 thru 314 )

The selections for adding and subtracting fuel are labeled " TABLE TOP ROW "
" TABLE 8th ROW "
" TABLE 7th ROW "

There are in fact 16 vertical rows !

Now I assume that the TOP ROW is at 314 KPa. Now out of the remaining rows, which is row 8 etc. Do they go down in 2's ( 2 rows at a time )

HELP ! What am I missing here?

George

 

[norbs]

Looks like some confusion,

The correction refers to the a/f correction table only, there are only 8 rows in that table. You are looking at the ve table which has 16 rows i think, and its throwing you off! Rows are horizontal, and columns are vertical. Easy mistake to make. Hope that helps ...


norb

 

[oldtimer]

Looks like some confusion,

The correction refers to the a/f correction table only, there are only 8 rows in that table. You are looking at the ve table which has 16 rows i think, and its throwing you off! Rows are horizontal, and columns are vertical. Easy mistake to make. Hope that helps ...


norb

Thanks for the FAST reply Norbs ( pun intended )

Yes I realize that it's the VE tables that have rows and columns but in what cells do the +/- corrections take place. In other words, I have +25 in the
TOP ROW down through ROW 5, so what I'm trying to figure out is what cells in the VE tables is the ECU adding fuel to, if the engine is running lean

My thinking might be screwed up in this but it "seems" to make sense to me that when the 02 senses the engine is lean/rich, it has to make a correction in an area of engine operation ( cell ), thus which cell ? Perhaps it's a block of cells vs any individual cells.

Help me to understand this. Bear with me, that's why I'm called Oldtimer

George

 

[sc68z28]

George, If I understand your question, I'd say its a rolling correction.

Looking at my own data logs, it appears the ECU +/- fuel when it sees leaner/richer than your target A/F is set. It will keep +/- fuel untill it sees it going the other way.

This will occur as the engine passes through many cells. It will not correct the cells V/E number. It will just change the injector time by up to the % you have allowed in that table.

Hope this helps, I'm still learning too. Bill.

 

[SPEEDSTAR]

GEORGE, WHATturbo,boost,.....
are you also running a distributor.......
which intake, got pics of stage 2

 

[oldtimer]

GEORGE, WHATturbo,boost,.....
are you also running a distributor.......
which intake, got pics of stage 2

Jeff,

I'm not having any serious problems presently. I'm just trying to understand the relationships between and behind the different screens of my F.A.S.T. set up. I believe the more of the theory that one understands of anything, diagnosing situations comes a lot easier. Just trying to learn more, in other words.

I'm running a Precision mid-frame 47-80 turbo and plan to be running 30# boost

I haven't installed my distributor yet. I have all the pieces set to go, but because this is a brand new combo with absolutely everything new and changed from my previous set up, I'm doing the initial tuning with the stock coil pac until I get the basic dial-in complete.

I'm running a Bowling Green intake !

There's a whole lot of info on my set up in the Stage 2 Tech Forum including pics and dyno sheet. The thread is titled " pic of my new Stage 2 by Cal Hartline" dated March 14th, 2006

Thanks for responding

George

 

[oldtimer]

George, If I understand your question, I'd say its a rolling correction.

Looking at my own data logs, it appears the ECU +/- fuel when it sees leaner/richer than your target A/F is set. It will keep +/- fuel untill it sees it going the other way.

This will occur as the engine passes through many cells. It will not correct the cells V/E number. It will just change the injector time by up to the % you have allowed in that table.

Hope this helps, I'm still learning too. Bill.

Thanks Bill,

Ya, it has to be a rolling type correction. With 16 rows of VE cells and 9 table rows, the corrections must be over a group of cells, not specific individual cells. I realize that the correction can't change the VE tables but can compensate for wrong settings ???? I think!

I was just trying to relate the Table Rows to specific VE cells

Perhaps Craig Smith can chime in

George

 

[bobc455]

You're on the right track.

All of the calculations are not dependant on just one cell, but a combination of cells where the engine is running.

If you watch the "bubble" on some 3D tables when the engine is running, you'll notice that the bubble floats over several cells most of the time. The ECM uses a weighted average out the values of the four cells where the bubble is floating (most weight given to the cell where most of the bubble is, etc.).

The same thing happens on 2D tables, the number the ECM uses is a weighted average of the two adjacent cells. In other words, if you are running at 1700 RPM, the ECM will average (3 X value in 1600 RPM cell) and (1X value in 2000 RPM cell).

Hope I'm not overcomplicating the explanation...

-Bob Cunningham

 

[norbs]

Its called interpolation, now thats a complicated word

 

[oldtimer]

You're on the right track.

All of the calculations are not dependant on just one cell, but a combination of cells where the engine is running.

If you watch the "bubble" on some 3D tables when the engine is running, you'll notice that the bubble floats over several cells most of the time. The ECM uses a weighted average out the values of the four cells where the bubble is floating (most weight given to the cell where most of the bubble is, etc.).

The same thing happens on 2D tables, the number the ECM uses is a weighted average of the two adjacent cells. In other words, if you are running at 1700 RPM, the ECM will average (3 X value in 1600 RPM cell) and (1X value in 2000 RPM cell).




Hope I'm not overcomplicating the explanation...

-Bob Cunningham

Thanks Bob,

I'm on a steep learning curve and I'm trying to understand what I "think" I understand. How's that for complication.

No, your not complicating it. I appreciate your input. I need all the help I can get. :smile:

George

 

[HighPSI]

Sorry George, I'm back from vacation now.

The row designations are based upon the Target A/F ratio table. Don't hesitate to email (or call) with any further questions.

 

[oldtimer]

Sorry George, I'm back from vacation now.

The row designations are based upon the Target A/F ratio table. Don't hesitate to email (or call) with any further questions.

Thanks Cal,

You have a voicemail message and an e-mail on another topic :wink:

George