LTFT Boundaries...anybody changing them?
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TECH Addict
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LTFT Boundaries...anybody changing them? Does changing the LTFT boundaries do anything useful? I saw an earlier post saying that they used Z06 boundaries to get more cells into play. Is there any more information out there? I already scoured the internet, and searched this website.
And what are the values for the Z06 LTFT boundaries (MAP and RPM) anyways?
And what are the values for the Z06 LTFT boundaries (MAP and RPM) anyways?
TTT again. I've seen a few posts about some cars (later years?) having the boundaries set at 2500/6502/6503 rpm, which means almost half the possible cells are never used (2,3,6,7,10,11,14,15). Mine is one, I never see these cells, I'd like to know if anyone has changed these and what was the result?
I don't think I can help much, but I have a 02 and changed these cells. I noticed a lot more cells that are used now. I am in the process of loging the car and making a new VE table for it.
I thought of one possible reason they changed these boundaries to eliminate half the cells: maybe it reduces the "learn" time. Each cell has to be learned separately, so... The tradeoff is less accurate fit of ltft for each cell, to the whole range of operating conditions for that cell. But, maybe they decided there wasn't that much variation across the bigger range. My own opinion is that more cells is better.
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TECH Resident
Joined: Jan 2002
Posts: 754
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From: USA
A older 98 with the same boundary values as a C5
What the engine used ONLY in this scanner drive !
CELLS LTFT-Avg
C1 -5.08
C2 -3.85
PE3 0.28
C5 -8.62
PT6 -2.28
PE7 -2.00
PT9 2.27
PT10 0.51
PE11 -1.41
PE13 5.50
PE14 5.73
WOT15 0.60
ACI17 -1.79
HOTI19 -4.08
COLDI20 -6.86
LIFT21 8.39
PE22 0.25
-----------------
Or a 02 SS
CELLS LTFT-Avg
C1 2.17
C2 0.05
PE3 2.59
C5 2.04
PT6 0.32
PE7 0.32
PT9 1.28
PT10 1.39
PE11 1.24
PE14 5.07
WOT15 4.62
ACI17 2.08
HOTI19 5.16
LIFT21 7.57
PE22 5.26
-------------------
Both use the same 23 trim cells IF the engine conditions were used for a certain cell.
Some cells are for auto trannie only so clearly a manual trannie never sees those cells, the same goes for if the A/C is used or not or even if the engine ever gets to a certain MAP/Vac load as example cell 0, very few engines get there.
A simple drive method of hauling *** and then a large lift of gas pedal will produce different cells used over small lift of gas pedal, same goes for when hammering gas pedal if the trannie was in 2nd gear over using 4th gear.
Stop and go city traffic produces different cells being hit then doing a testrun on the highway.
The reason to move boundary around is only if a cam such as one that has a 112 LSA which hikes up MAP, lowers vaccum thus when engine is at idle and should be in cell 19 the cam has caused idle MAP/Vac to now be where cell 18 is so the boundary has changed.
Frankly I do not think the boundary table in LS1edit even works and may be even pointing to some other function's offset address since clearly using a '98 values in a '02 I see no changes.
If you want to PCM to relearn more cells quicker use the GM drive cycle method.
What the engine used ONLY in this scanner drive !
CELLS LTFT-Avg
C1 -5.08
C2 -3.85
PE3 0.28
C5 -8.62
PT6 -2.28
PE7 -2.00
PT9 2.27
PT10 0.51
PE11 -1.41
PE13 5.50
PE14 5.73
WOT15 0.60
ACI17 -1.79
HOTI19 -4.08
COLDI20 -6.86
LIFT21 8.39
PE22 0.25
-----------------
Or a 02 SS
CELLS LTFT-Avg
C1 2.17
C2 0.05
PE3 2.59
C5 2.04
PT6 0.32
PE7 0.32
PT9 1.28
PT10 1.39
PE11 1.24
PE14 5.07
WOT15 4.62
ACI17 2.08
HOTI19 5.16
LIFT21 7.57
PE22 5.26
-------------------
Both use the same 23 trim cells IF the engine conditions were used for a certain cell.
Some cells are for auto trannie only so clearly a manual trannie never sees those cells, the same goes for if the A/C is used or not or even if the engine ever gets to a certain MAP/Vac load as example cell 0, very few engines get there.
A simple drive method of hauling *** and then a large lift of gas pedal will produce different cells used over small lift of gas pedal, same goes for when hammering gas pedal if the trannie was in 2nd gear over using 4th gear.
Stop and go city traffic produces different cells being hit then doing a testrun on the highway.
The reason to move boundary around is only if a cam such as one that has a 112 LSA which hikes up MAP, lowers vaccum thus when engine is at idle and should be in cell 19 the cam has caused idle MAP/Vac to now be where cell 18 is so the boundary has changed.
Frankly I do not think the boundary table in LS1edit even works and may be even pointing to some other function's offset address since clearly using a '98 values in a '02 I see no changes.
If you want to PCM to relearn more cells quicker use the GM drive cycle method.
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I see you have the FTCs labeled Cx, PTy, PEz
(cruise, part-throttle, power enrichment?). One
thing I've been confused by, maybe you know,
is how a cell that (by all appearances) should
always be PE (thus fuel/air multiplier >1.0) can
have learning going on and a valid-appearing
fuel trim value? For example, PE11, PE14 are well
above the usual PE MAP enable; same with WOT15.
Why do these have sane-looking (though not
necessarily ideal) LTFT values, if learning is
suppressed in PE / FAM<>1.0?
(cruise, part-throttle, power enrichment?). One
thing I've been confused by, maybe you know,
is how a cell that (by all appearances) should
always be PE (thus fuel/air multiplier >1.0) can
have learning going on and a valid-appearing
fuel trim value? For example, PE11, PE14 are well
above the usual PE MAP enable; same with WOT15.
Why do these have sane-looking (though not
necessarily ideal) LTFT values, if learning is
suppressed in PE / FAM<>1.0?
TECH Resident
Joined: Jan 2002
Posts: 754
Likes: 0
From: USA
To meet a certain cell's requirement it takes a certain MAP and RPM values and also depends on if Fuel Learn is ON or OFF.
if you look at the matrix as an example
0 1 2 3
4 5 6 7
8 9 10 11
12 13 14 15
16 17 18 19
20 21 22 23
It becomes clear that cells 0 and 4 require less MAP and RPMs as cells 3 and 7
so 3 and 7 would be PE as long as the other conditions are met where most people are just looking at the TPS angle V RPMs but are not looking to see if PCM agreed the PE conditions were met and flipped off fuel learn.
Tuning boundary table such as in LS1edit is only broke up with 3 boundaries when there is 6 ( 4*6 = 24 (cell 23 in reserve))
In OBD-I there was 16 cells, thus cell 15 = WOT but EPA demanded more control for OBD-II esp for A/C on or off or a auto trannie in park, neutral or idle in drive thus more cells were added on.
if you look at the matrix as an example
0 1 2 3
4 5 6 7
8 9 10 11
12 13 14 15
16 17 18 19
20 21 22 23
It becomes clear that cells 0 and 4 require less MAP and RPMs as cells 3 and 7
so 3 and 7 would be PE as long as the other conditions are met where most people are just looking at the TPS angle V RPMs but are not looking to see if PCM agreed the PE conditions were met and flipped off fuel learn.
Tuning boundary table such as in LS1edit is only broke up with 3 boundaries when there is 6 ( 4*6 = 24 (cell 23 in reserve))
In OBD-I there was 16 cells, thus cell 15 = WOT but EPA demanded more control for OBD-II esp for A/C on or off or a auto trannie in park, neutral or idle in drive thus more cells were added on.
The only thing I've seen for "fuel learn" is that it
doesn't learn, if the fuel/air multiplier is <> 1.0
(makes sense since the O2s would then be no
good). So being into PE would do that, as would
some of the Open Loop A/F vs MAP vs ECT table.
Not clear on what conditions put that one in play,
either.
But some of these cells look like they can't help
being PE (like, how can you get to cell 14 without
both high MAP and high throttle angle (high RPM)?)
yet they still seem to have "learned" somehow?
Is there a dedicated "flag" other than the fuel/air
multipler that indicates "learn/no-learn" directly?
doesn't learn, if the fuel/air multiplier is <> 1.0
(makes sense since the O2s would then be no
good). So being into PE would do that, as would
some of the Open Loop A/F vs MAP vs ECT table.
Not clear on what conditions put that one in play,
either.
But some of these cells look like they can't help
being PE (like, how can you get to cell 14 without
both high MAP and high throttle angle (high RPM)?)
yet they still seem to have "learned" somehow?
Is there a dedicated "flag" other than the fuel/air
multipler that indicates "learn/no-learn" directly?
Originally Posted by Team ZR-1
To meet a certain cell's requirement it takes a certain MAP and RPM values and also depends on if Fuel Learn is ON or OFF.
if you look at the matrix as an example
0 1 2 3
4 5 6 7
8 9 10 11
12 13 14 15
16 17 18 19
20 21 22 23
It becomes clear that cells 0 and 4 require less MAP and RPMs as cells 3 and 7
so 3 and 7 would be PE as long as the other conditions are met where most people are just looking at the TPS angle V RPMs but are not looking to see if PCM agreed the PE conditions were met and flipped off fuel learn.
Tuning boundary table such as in LS1edit is only broke up with 3 boundaries when there is 6 ( 4*6 = 24 (cell 23 in reserve))
In OBD-I there was 16 cells, thus cell 15 = WOT but EPA demanded more control for OBD-II esp for A/C on or off or a auto trannie in park, neutral or idle in drive thus more cells were added on.
if you look at the matrix as an example
0 1 2 3
4 5 6 7
8 9 10 11
12 13 14 15
16 17 18 19
20 21 22 23
It becomes clear that cells 0 and 4 require less MAP and RPMs as cells 3 and 7
so 3 and 7 would be PE as long as the other conditions are met where most people are just looking at the TPS angle V RPMs but are not looking to see if PCM agreed the PE conditions were met and flipped off fuel learn.
Tuning boundary table such as in LS1edit is only broke up with 3 boundaries when there is 6 ( 4*6 = 24 (cell 23 in reserve))
In OBD-I there was 16 cells, thus cell 15 = WOT but EPA demanded more control for OBD-II esp for A/C on or off or a auto trannie in park, neutral or idle in drive thus more cells were added on.
Thread Starter
TECH Addict
Joined: Feb 2004
Posts: 2,826
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I think that the trim boundaries don't effect idle because there is a vehicle speed at which the vehicle transition form the idle cells to the non-idle cells (which I am pretty sure is adjustable).
I am also not convinced that PE and the last cell you were in are the only things that affect WOT. I have another (completely unfounded, but that I am working on) idea that the VE table once again comes into play. Maybe.
I am also not convinced that PE and the last cell you were in are the only things that affect WOT. I have another (completely unfounded, but that I am working on) idea that the VE table once again comes into play. Maybe.
