This lean spool is confusing.. all I want to know since disabling it brings you closer to A/F from your map.. and makes you richer as well.. giving you a different reading on your wideband..

Will you by leaning out your new A/F displayed on your gauge gain more power.. !

Gain the power by adjusting your fuel table, timing, logging knock and maybe adjusting your boost.. to an ideal 11.5:1 A/F..!! Is this the PRO about it.. this is what am understanding.. if not.. then what..? what's the pros and con about this..

 

Lean spool adjusts the AFR on a timer, so not only is the AFR rpm dependent, its also time dependent. If you are looking for pure rpm dependence (most people are), then disable it.

 

There is no power to be made from disabling lean spool (OEM richening by the ECU from 2500-7000). What is gained is the transition areas are easier to tune with lean spool disabled (IMO). The boost area fueling values remain arbitrary and not actual AFR numbers. If you disable your lean spool you will be pig rich because they are setup to run with lean spool enabled so you have to lean them to your desired AFR. I have both my enable and disable set to 0 and I havent noticed any side effects. maybe I should try 1500?

The obvious: If you dont have a wideband or know how to tune an entire fuel map then dont mess with lean spool because it will change your fuel map from 2500-7000 and you can't guess what it should be afterwards.

 

I'll just toss this out there ...

I've wondered what exactly the lean spool feature does. I've had it disabled on my car for a while, so I hadn't really thought about it.

I was tuning a friend's car the other day and as we neared the end, we tried some high gear pulls (5th and 6th). As boost came in in higher gears the AFR went nearly a full point rich randomly. It was a inconsistent change ... sometimes at 4000 ... sometimes at 5500. The change was instant and there was no knock present.

The next day he was at the track and noticed the shift again ... it was fairly constant in 4th gear. The AFR stayed about 1 point richer than we had tuned the night before.

Lean spool was still enabled on his car because I didn't have the modified values for the IX v13 ROM on my computer. Was this shift caused by the lean spool settings, and why was this happening?

 

Very likely yes. Lean spool is designed to richen the afr over a set period of time. The "instantaneous" aspect doesn't jive, but richer afr in higher gears is the intent of lean spool. From what I've seen of other people's experiences, it doesn't seem to work quite a neatly as the concept I explained.

 

So lean spool is a transient enrichment, not an enleanment? If that's the case it should be called "rich spool"...

Most factory turbo cars have just such an transient enrichment based on MAP or load rate-of-change. It would make sense that the Evo does too.

 

This was a fast jump from the tuned ~11.4:1 to about 10.5:1 ... I assumed lean spool because the odd values were about 1 point from the map values, much like a non-lean spool AFR value would be. So, like 9.6 in the map gives ~11.4 AFR and it would jump to 10.5.

We tuned for 4th gear if it matters ...

 

It can be thought of as a transient enleanment or a gradual enrichment. The code itself leans out the afr and is supposed to gradually let it reach its "normal" afr over a set period of time. The idea is to help control knock under sustained high load conditions. If lean spool worked really well, it seems like it would be a good thing to have.

Evo's also have a transient enrichment for rapid load changes. Its different than lean spool.

 

I removed LS to make AFRMAP logs closer to the AFR map and to gain more control over the fuel map.

After it was dissiabled I immediatly leaned the map back to a leaner transition from 100 - 180% load where it was effected - it was way too rich once disabled and knocking.

 

AFR is reduced by a fixed decimal value on engagement and is timer baed on start of current rpm.. higher rpms= lower timer values..

there is no addition from what I see.. it only normalise the fuel after a fixed time..

If you disable it.. you should get consistent AFR thru out the gears..

it is designed to accelerate faster at lower gears and preserve engine at sustained high speed = rally / autocross types