Lean Spool Trailing Time
What ever is input in the 1st three cells of the "V" part of the table has a direct effect on the AFRMAP value durring a enabled lean spool condition. It's pretty darn close to logged AFRMAP values too if you set "V" to read as "unint 8"
Joined: Mar 2003
Posts: 394
Likes: 7
From: Used to be in Nor Cal, now working in Seoul
Ok, let me bring this thread back to alive. 
I know many people disable lean spool to get more consistent AFR and may sacrifice very little spool up time, but I hope someone found out how this trailing time really works.
It seems my ROM has "Lean Spool Trailing Time (Rich Side)":
RPM/Time
500~2000/9
2500/4
3000/3
3500/3
4000/2
4500/2
5000~7000/1
Which I think makes sense because high rpm spool time is much less, therefore, there is no need to stay at Rich side for a long time. Although I am not sure how long is "1" time is here. (Same as boost control correction time? 0.08~0.1 sec?)
Then my ROM has "Lean Spool Trailing Time (Lean Side)":
RPM/Time
500~2000/9
2500/4
3000/5
3500/7
4000/12
4500/10
5000/11
5500/11
6000~7000/1
By the way, it seems the address for "Lean Spool AFR Mapping" and "Lean Spool AFR below Enable" and "Lean Spool Clip Value" addresses for 94170008 were wrong. After adjusting the addresses around, I got
"Lean Spool AFR Mapping":
Base AFR/AFR
14.7/14.7
13.1/13.1
11.8/13.1
10.7/12.0
9.8/10.9
9.0/10.2
8.4/9.5
"Lean Spool AFR below Enable"
13.0
"Lean Spool Clip Value"
14.7
That should explain why people were experiencing about 1 full AFR richer after lean spool is disabled.
I hope some ECU gurus can confirm if I understand how this Lean Spool actually works correctly:
If I go WOT from 3500rpm,
ECU leans out the AFR for 7 time units by the lean spool AFR mapping table,
Then ECU richens up the AFR for 3 time units back to the base fuel map,
Then ECU remains at the base AFR from the fuel map table until going out of open-loop fuel control. (eg. end of WOT or gear change)
Is this the way lean spool actually works?
If my guess is right, since rpm rise speed at 2nd gear is faster than 5th gear, but if I go WOT from 3000rpm, lean spool works for the same (5 + 3) time units, I actually go back to the base fuel map at much lower rpm when I am in 5th gear than 2nd gear?
For example, WOT from 3000rpm during (5 + 3) time units ended at 6000rpm (just an example) in 2nd gear, and the same WOT ended at 4000rpm (just an example) in 5th gear, we should see richer AFR condition earlier at high gears.
This might explain why lean spool actually gives richer AFR at high gears as much as 1 full AFR point? (Because of earlier termination of lean spool in terms of rpm)
I guess if we understand this lean spool mechanism correctly, we should be able to use this for better spool and good AFR control.
Thank you for reading such a long post.
I know many people disable lean spool to get more consistent AFR and may sacrifice very little spool up time, but I hope someone found out how this trailing time really works.
It seems my ROM has "Lean Spool Trailing Time (Rich Side)":
RPM/Time
500~2000/9
2500/4
3000/3
3500/3
4000/2
4500/2
5000~7000/1
Which I think makes sense because high rpm spool time is much less, therefore, there is no need to stay at Rich side for a long time. Although I am not sure how long is "1" time is here. (Same as boost control correction time? 0.08~0.1 sec?)
Then my ROM has "Lean Spool Trailing Time (Lean Side)":
RPM/Time
500~2000/9
2500/4
3000/5
3500/7
4000/12
4500/10
5000/11
5500/11
6000~7000/1
By the way, it seems the address for "Lean Spool AFR Mapping" and "Lean Spool AFR below Enable" and "Lean Spool Clip Value" addresses for 94170008 were wrong. After adjusting the addresses around, I got
"Lean Spool AFR Mapping":
Base AFR/AFR
14.7/14.7
13.1/13.1
11.8/13.1
10.7/12.0
9.8/10.9
9.0/10.2
8.4/9.5
"Lean Spool AFR below Enable"
13.0
"Lean Spool Clip Value"
14.7
That should explain why people were experiencing about 1 full AFR richer after lean spool is disabled.
I hope some ECU gurus can confirm if I understand how this Lean Spool actually works correctly:
If I go WOT from 3500rpm,
ECU leans out the AFR for 7 time units by the lean spool AFR mapping table,
Then ECU richens up the AFR for 3 time units back to the base fuel map,
Then ECU remains at the base AFR from the fuel map table until going out of open-loop fuel control. (eg. end of WOT or gear change)
Is this the way lean spool actually works?
If my guess is right, since rpm rise speed at 2nd gear is faster than 5th gear, but if I go WOT from 3000rpm, lean spool works for the same (5 + 3) time units, I actually go back to the base fuel map at much lower rpm when I am in 5th gear than 2nd gear?
For example, WOT from 3000rpm during (5 + 3) time units ended at 6000rpm (just an example) in 2nd gear, and the same WOT ended at 4000rpm (just an example) in 5th gear, we should see richer AFR condition earlier at high gears.
This might explain why lean spool actually gives richer AFR at high gears as much as 1 full AFR point? (Because of earlier termination of lean spool in terms of rpm)
I guess if we understand this lean spool mechanism correctly, we should be able to use this for better spool and good AFR control.
Thank you for reading such a long post.
Last edited by ace33joe; Dec 5, 2008 at 03:55 PM. Reason: Correct the order of lean spool AFR transition
By the way, it seems the address for "Lean Spool AFR Mapping" and "Lean Spool AFR below Enable" and "Lean Spool Clip Value" addresses for 94170008 were wrong. After adjusting the addresses around, I got
"Lean Spool AFR Mapping":
Base AFR/AFR
14.7/14.7
13.1/13.1
11.8/13.1
10.7/12.0
9.8/10.9
9.0/10.2
8.4/9.5
"Lean Spool AFR below Enable"
13.0
"Lean Spool Clip Value"
14.7
I think the lean spool trailing tables are also incorrect. They seem to be referecend to RPM tables that are much larger then the tables for the lean spool stuff and the jump in the rich side table seems to be the end of a table?
Joined: Mar 2003
Posts: 394
Likes: 7
From: Used to be in Nor Cal, now working in Seoul
Mapping = 6399
Enable = 1683
Clip Value = 1687
Do you have correct address for the lean spool trailing tables?
I guess my guess was wrong, maybe lean spool starts from the lean side then go to rich side (probably for smoother AFR transition to rich side).
Enable = 1683
Clip Value = 1687
Do you have correct address for the lean spool trailing tables?
I guess my guess was wrong, maybe lean spool starts from the lean side then go to rich side (probably for smoother AFR transition to rich side).
ace33joe
Your address values all seem to be 1 unit off from what I have seen others say they should be. Did you get your addresses from dissassembly?
Unfortunately, using 6399 doesn't give me the same values you get for base AFR in the AFR mapping table. Using 6654 (old "Boost Enhancement Table") gives me the same values you have though for this table.
Your address values all seem to be 1 unit off from what I have seen others say they should be. Did you get your addresses from dissassembly?
Unfortunately, using 6399 doesn't give me the same values you get for base AFR in the AFR mapping table. Using 6654 (old "Boost Enhancement Table") gives me the same values you have though for this table.
Joined: Mar 2003
Posts: 394
Likes: 7
From: Used to be in Nor Cal, now working in Seoul
No, it is not from disassembly. Before changing the address as I wrote, those values were all looked strange to me. (AFR clip value was 0.1 rather than 14.7, for example)
Are you using 94170008 by the way? I guess the addresses would be different from other ECUs.
Are you using 94170008 by the way? I guess the addresses would be different from other ECUs.
Ok, let me bring this thread back to alive.
I know many people disable lean spool to get more consistent AFR and may sacrifice very little spool up time, but I hope someone found out how this trailing time really works.
It seems my ROM has "Lean Spool Trailing Time (Rich Side)":
RPM/Time
500~2000/9
2500/4
3000/3
3500/3
4000/2
4500/2
5000~7000/1
Which I think makes sense because high rpm spool time is much less, therefore, there is no need to stay at Rich side for a long time. Although I am not sure how long is "1" time is here. (Same as boost control correction time? 0.08~0.1 sec?)
Then my ROM has "Lean Spool Trailing Time (Lean Side)":
RPM/Time
500~2000/9
2500/4
3000/5
3500/7
4000/12
4500/10
5000/11
5500/11
6000~7000/1
By the way, it seems the address for "Lean Spool AFR Mapping" and "Lean Spool AFR below Enable" and "Lean Spool Clip Value" addresses for 94170008 were wrong. After adjusting the addresses around, I got
"Lean Spool AFR Mapping":
Base AFR/AFR
14.7/14.7
13.1/13.1
11.8/13.1
10.7/12.0
9.8/10.9
9.0/10.2
8.4/9.5
"Lean Spool AFR below Enable"
13.0
"Lean Spool Clip Value"
14.7
That should explain why people were experiencing about 1 full AFR richer after lean spool is disabled.
I hope some ECU gurus can confirm if I understand how this Lean Spool actually works correctly:
If I go WOT from 3500rpm,
ECU leans out the AFR for 7 time units by the lean spool AFR mapping table,
Then ECU richens up the AFR for 3 time units back to the base fuel map,
Then ECU remains at the base AFR from the fuel map table until going out of open-loop fuel control. (eg. end of WOT or gear change)
Is this the way lean spool actually works?
If my guess is right, since rpm rise speed at 2nd gear is faster than 5th gear, but if I go WOT from 3000rpm, lean spool works for the same (5 + 3) time units, I actually go back to the base fuel map at much lower rpm when I am in 5th gear than 2nd gear?
For example, WOT from 3000rpm during (5 + 3) time units ended at 6000rpm (just an example) in 2nd gear, and the same WOT ended at 4000rpm (just an example) in 5th gear, we should see richer AFR condition earlier at high gears.
This might explain why lean spool actually gives richer AFR at high gears as much as 1 full AFR point? (Because of earlier termination of lean spool in terms of rpm)
I guess if we understand this lean spool mechanism correctly, we should be able to use this for better spool and good AFR control.
Thank you for reading such a long post.
I know many people disable lean spool to get more consistent AFR and may sacrifice very little spool up time, but I hope someone found out how this trailing time really works.
It seems my ROM has "Lean Spool Trailing Time (Rich Side)":
RPM/Time
500~2000/9
2500/4
3000/3
3500/3
4000/2
4500/2
5000~7000/1
Which I think makes sense because high rpm spool time is much less, therefore, there is no need to stay at Rich side for a long time. Although I am not sure how long is "1" time is here. (Same as boost control correction time? 0.08~0.1 sec?)
Then my ROM has "Lean Spool Trailing Time (Lean Side)":
RPM/Time
500~2000/9
2500/4
3000/5
3500/7
4000/12
4500/10
5000/11
5500/11
6000~7000/1
By the way, it seems the address for "Lean Spool AFR Mapping" and "Lean Spool AFR below Enable" and "Lean Spool Clip Value" addresses for 94170008 were wrong. After adjusting the addresses around, I got
"Lean Spool AFR Mapping":
Base AFR/AFR
14.7/14.7
13.1/13.1
11.8/13.1
10.7/12.0
9.8/10.9
9.0/10.2
8.4/9.5
"Lean Spool AFR below Enable"
13.0
"Lean Spool Clip Value"
14.7
That should explain why people were experiencing about 1 full AFR richer after lean spool is disabled.
I hope some ECU gurus can confirm if I understand how this Lean Spool actually works correctly:
If I go WOT from 3500rpm,
ECU leans out the AFR for 7 time units by the lean spool AFR mapping table,
Then ECU richens up the AFR for 3 time units back to the base fuel map,
Then ECU remains at the base AFR from the fuel map table until going out of open-loop fuel control. (eg. end of WOT or gear change)
Is this the way lean spool actually works?
If my guess is right, since rpm rise speed at 2nd gear is faster than 5th gear, but if I go WOT from 3000rpm, lean spool works for the same (5 + 3) time units, I actually go back to the base fuel map at much lower rpm when I am in 5th gear than 2nd gear?
For example, WOT from 3000rpm during (5 + 3) time units ended at 6000rpm (just an example) in 2nd gear, and the same WOT ended at 4000rpm (just an example) in 5th gear, we should see richer AFR condition earlier at high gears.
This might explain why lean spool actually gives richer AFR at high gears as much as 1 full AFR point? (Because of earlier termination of lean spool in terms of rpm)
I guess if we understand this lean spool mechanism correctly, we should be able to use this for better spool and good AFR control.
Thank you for reading such a long post.
Id also like to know if anyone can shed some insight onto what exactly triggers the ecu into the lean side table. Is it 100% tps? Greater than xx% TPS? Or a specific change in TPS delta?
Its pretty neat graphing AFRMAP with and without it disabled. Especially with real AFR #s in the fuel map. Im continuing to tinker with the timing tables, but to be honest...I think the lean side table should almost be inverse of the rich side table. But all of the examples I see show them both following a similar pattern with the exception of some showing a dip around 3k.
(edit: I just looked at the example in the quote above again and it matches the inverse curve Id expect. Has that been modified from stock? All the examples Im referring to are from dowloaded "stock" roms and merlins guide example)
My understanding is that when the trigger for LS happens, the ECU looks at the Lean side tables and that is the time it takes to go from normal AFR to Lean AFR. Then the Rich side takes over and controls how long the effect lasts. Thats why I think it should make more sense to have less time in the lower rpm and more time in the upper rpm for entry to lean condition. Seems safer? And quicker spooling for when you need it down low, since there is virtually no lag up top anyways.
My goal is 12.0-11.5 in 1st, 11.8-11.3 in 2nd and fall back into normal 11.0 for the upper end of 3rd moreso in 4th and 5th. Autocross car.
Any insight would be appreciated. I know several of you use it and love it. I like it, just want to make sure Im controlling it and using it to its full advantage.
Last edited by charlie.tunah; May 17, 2014 at 05:53 AM.
Evolved Member
Joined: Jun 2008
Posts: 824
Likes: 23
From: Sydney
charlie, I had another look at this last night after your post, and could not find any relevant 1D parameters that looked like throttle or load L-S activation triggers. Or anything else that might trigger the function. Sorry m8.
Im running the settings in the attached file at the moment and plan to adjust the Rich side tables by themselves to see if it directly changes the time you spend in LS mode. I am still a little confused how to setup the lean side table.
I think there is another thread where I explained my approach pretty well on how to go about running these tables.
It's been a long *** time though so I don't really remember what thread it was in. The jists is there is a counter and one table decrements the counter based on how long you've been above the load threshold. The second table adds back to the counter when you aren't above the threshold. That counter is used to interpolate between the mapped afr and the AFR correction table.
If the counter shows max value then you get the full enleanment based on the AFR correction table. If you've been above the load threshold long enough that the counter has decremented to zero, the AFR is the mapped AFR with no additional enleanment.
It's been a long *** time though so I don't really remember what thread it was in. The jists is there is a counter and one table decrements the counter based on how long you've been above the load threshold. The second table adds back to the counter when you aren't above the threshold. That counter is used to interpolate between the mapped afr and the AFR correction table.
If the counter shows max value then you get the full enleanment based on the AFR correction table. If you've been above the load threshold long enough that the counter has decremented to zero, the AFR is the mapped AFR with no additional enleanment.
I was getting some odd results this weekend during autocross. Really slow spool in 1st and 2nd (<4000) and very rich afr in grid, even in closed loop. So I disabled LS and it all seemed to go away. Everything above 4k has been great doing quick runs through the gears. Im going to change these tables back to what they were.
'03 is there any chance you can share your trailing time tables?
'03 is there any chance you can share your trailing time tables?
Evolved Member
Joined: Jun 2008
Posts: 824
Likes: 23
From: Sydney
Back in March 2009, jcsbanks and mrfred did do some investigations into how the routine works and posted up the relevant data. 02whitegsr also posted his tuning notes which are quite helpful. Unfortunately I did not make appropriate xml amendments or tuning notes - curse.
Anyway, the decay tables would be more accurately described as:
Lean-Spool Step-Time, Lean to Rich
Lean-Spool Step-Time, Rich to Lean
The values in the tables are step-times, ie the run time before the interpolation factor is incremented (from 0, when LS is first triggered, so the full effect of LS is applied),
and decremented (when load drops below the threshold) from what ever value the interpolation factor reached back to zero.
As 03whitegsr points out, reducing the values will shorten the timers.
Anyway, the decay tables would be more accurately described as:
Lean-Spool Step-Time, Lean to Rich
Lean-Spool Step-Time, Rich to Lean
The values in the tables are step-times, ie the run time before the interpolation factor is incremented (from 0, when LS is first triggered, so the full effect of LS is applied),
and decremented (when load drops below the threshold) from what ever value the interpolation factor reached back to zero.
As 03whitegsr points out, reducing the values will shorten the timers.