1. Does the ECU lean out the values in the fuel map or does it run its own little algorithm? Question stems from the fact that while on pump gas with an 11:1 afr tune I still see 12.5:1 AFR through the first gear that I hammer it in. Now I want to lean my AFR out for 100 oct to 12:1 through the entire power band but I dont want the ECU to then lean that mixture out to 13.5:1.

2. Can I configure the RPM that I want lean spool to stop at? I now know the anitlag start and stop number do not acutally translate into RPM but I would like to enter the value that would control or lessen the depth of my lean spool. I would like things leaned out till 3500 after that I would prefer the AFR I dialed in. If there isn't a way I suppose disabling lean spool is my only option. I'm afraid that overal performance will be affected because many have reported sub-par results with it turned off.

 

fROM what I experienced, the lean spool just makes the value in the map (for the respective lean spool portion) overridden to a point . I personally prefer leaner spool - just faster - and leaned it back to where it was with it enabled, however I disabled to gain more control of my map

As for the portion of RPM which is controllable is still unkown (I think) for the value in there is not really RPM (i.e 4350), jsc may know the details of RPM control though

 

If you had the same map and your variables were only lean spool on or off. You would see something like the following:

3500 rpm 12.1 AFR (lean spool on)
3500 rpm 11.4 AFR (lean spool off)

Turning it all the way off will richen it anywhere from .7-1.0 full AFR. If you want to experiment it wont do anything but go rich so disable it and log and see what the change is in your particular setup.

For your initial question set the lean spool enable to 2500 (default) and the disable at 3500 and watch what it does.

 

Its not worth it to imo to turn it off since the change in the AFRs ar 3k is Drastic. You end up running to risk. No need, just use the lean spool on.

 

What risk? the risk of being slightly richer

 

I noticed when playing with an 8MR UK/JDM that if the AFR in 3rd gear was 11.5 it would be 10.7 in higher gears.

With lean spool enabled on my IX I only see about 0.3 AFR difference between 3rd and 6th gear.

Both setups had the fuel map AFRs flat over a wide range of loads from 200+ load.

 

Opps what the hell was i typing lol....

I just meant to u run rich, no risk.

But u will be slower, fwiw

 

np, I figured you didn't mean that but wanted to be clear

 

I have a similar experience with an EVOVII ECU in a EVOVI TME.

AFR 2nd gear 12.4
AFR 3rd gear 11.8
AFR 4th gear 10.8

Same boost (1.2 bar), same MAF Hz, same "load".


For those of us who are used to tuning aftermarket ECU's this is VERY annoying
I was going nuts trying to figure out what was going on until I read the threads on this "lean spool stuff".

I spent a whole morning road tuning in 3rd gear (not too fast on the road and rev's out slow enough to get good UEGO data) to get nice safe 11.8 AFR then went to the dyno which we run in 4th gear and bang 10.8 AFR, I thought man what is going on here

While the discussion on "lean spool" has been very useful the only way I can see the ECU doing this is there must be a "vehicle speed factor" (probably not) OR a "rate of engine acceleration factor" because these are the ONLY things different in each gear.

I am tending to think is a "rate of engine acceleration" factor. Maybe somebody can have a look in the code and see what they find?

We did another test (which I did not log ) where we set the dyno to hold (ie. zero engine acceleration) at 5000 RPM in 4th gear we went to full load for a few seconds and you could watch the AFR steadily going richer like there was some fuel "correction factor" happening.

So my theory is "a rate of engine acceleration factor which adds more fuel the slower the engine is accelerating" or saying it a different way "takes fuel out the faster the engine is accelerating".

Maybe this "factor" is what has been described as "lean spool"?

 

jcsbanks has determined what appears to be all the lean spool parameters. It looks like lean spool is timer based. I've found all the tables for a USDM Evo IX. I can post up the addresses if anyone is interested.

 

Here are the lean spool tables for the Evo 8 94170008:

------------
<table name="Lean Spool Start RPM" category="Misc" address="1680" type="1D" level="1" scaling="RPMStatLimit"/>

<table name="Lean Spool Stop RPM" category="Misc" address="1684" type="1D" level="1" scaling="RPMStatLimit"/>

<table name="Lean Spool Load Threshold" category="Misc" address="39A2" type="2D" level="1" scaling="Load8">
<table name="input value" address="63DA" type="X Axis" elements="14" scaling="RPM"/>
</table>

<table name="Lean Spool Trailing Time (Rich Side)" category="Misc" address="397A" type="2D" level="1" scaling="uint8">
<table name="input value" address="63DA" type="X Axis" elements="14" scaling="RPM"/>
</table>

<table name="Lean Spool Trailing Time (Lean Side)" category="Misc" address="398E" type="2D" level="1" scaling="uint8">
<table name="input value" address="63DA" type="X Axis" elements="14" scaling="RPM"/>
</table>

<table name="Min Temp for Lean Spool" category="Misc" address="167E" type="1D" level="1" scaling="Temp"/>

<table name="Lean Spool Enable Load Hysteresis" category="Misc" address="167C" type="1D" level="1" scaling="Load16"/>

<table name="Lean Spool AFR Mapping" category="Misc" address="39B6" type="2D" level="1" scaling="AFR">
<table name="base AFR" address="6400" type="X Axis" elements="7" scaling="AFR16"/>
</table>

<table name="Lean Spool AFR below Enable" category="Misc" address="1682" type="1D" level="1" scaling="AFR16"/>

<table name="Lean Spool Clip Value" category="Misc" address="1686" type="1D" level="1" scaling="AFR16"/>
------------

You'll also need to add this line to the "evo7base.xml" file:

------------
<scaling name="AFR16" units="AFR" toexpr="14.7*128/x" frexpr="14.7*128/x" format="%.1f" min="8" max="20" inc="0.1" storagetype="uint16" endian="little"/>
------------

EDIT: Added some entries that I forgot to copy over the first time.

 

Thanks for the info I will see how these addresses line up in the JDM EVO7 ROM.

 

They should be pretty close, but maybe not lined up. If you haven't disassembled your ROM, send it to me, and I'll find the tables for you. PM me if you are interested.

 

Just to clarify, with mine at least, wether LS is enabled or disenabled my AFR has a steady decline going through the gears.

The gear range and AFR are as such - 2nd gear AFR picks up where 1st left off, and the same goes for the rest of the gears where leanest is the beginning of 1st and richest is the end of the highest gear run. I'm pretty sure this is independent on LS enabled or disenabled

 

Ok set "lean spool" start and end RPM both at 1500.

AFR 2nd gear 11.8
AFR 3rd gear 11.8
AFR 4th gear 11.6

Seems good now. This is on EVOVII ECU, EVOVIII may have different stratergy/code.

Still like to know more about this feature.