Yes, But...

All good stories start that way right? So the deal is with the lean spool on in my experience tip in AFRs are locked and will stay constant somewhere from 12.4-12.7:1 before boost really starts peaking despite ROM/Map changes. Lean spool disabled, it goes to the base map without modifiers and you can alter it from there to what you want it. Advantage? Maybe if you know what you want your tip in AFRs to be, 99% of people probably are better leaving this alone but there are other reasons to turn it off. Its about like debating whether Peanut Butter and Jelly is better than PB and Jam. From the outside the look the same, they taste mostly the same, the textures are about the only difference.

JB

 

Well everything is trial and error....

 

Thats the same conclusion I came too, yes you can have more control over your AFR but is it really worth it if you are hitting the AFR's aimed at???

What confuses me are the other load cells when you are off-boost, what should they be set too? Too much hassle setting it all up. IMHO

 

I kind of like the lean spool since it doesn't really cause any problems. I plan to set the stop RPM to redline instead of 7k.

Here are the affects lean spool on my FAT road racing tune.

(Files were renamed from csv to zip you need to rename them.)

 

It has some really good uses. I mean when I want a racegas tune (other than timing) all I theoretically have to do is re-enable it and whammo I got the AFR I need for racegas. IF you adjust it with a wide enough window then yeah its not really an issue. I just like a little richer tip in and a little more timing so I run without it.

 

The other load cells need to be tuned as follows.

Obviously,



0-100, 500-5500rpm loads need to be tuned for 14.68:1(14.7:1), after 6000rpm, slowly richen up the mixture, to about 12.7-13.0:1 until revlimiter. Loads cells 100-140 should be a little richer, about 12.5-13.0:1......after about 160 you should be tuned for 11.5:1 between 3000-4000rpm, tapering down to 11.1:1 or so at revlimiter. This is a very short run down....but should get you close enough.

OBviously, closed/open loop crossovers are important to get these correct, but good thing is.....the stock crossover values are perfect for the stock turbo. If you are running a larger turbo, you may need to alter these values to hit your target AFR's in part throttle low load and part throttle high load.

I really don't see a problem with lean spool at all....TBH. It does exactly what i want it to. There are incidents where you might want to disable it....but not for most people using most set-ups.

CJ`

 

Exactly what I was trying to say earlier. 99.9% of all people are probably better off leaving it alone, myself included. I just tune according to some habits and this is one of my current ones.

 

While i agree to some extent with you^, with the lean spool disabled the afrs are easier to tune for each gear.

Ie- Lean spool disabled all gears typically follow the same AFR's

Lean spool enabled, you need to tune, 11.7:1 2nd gear, 11.3:1 3rd and 10.9:1 4th to keep the Afr's in the lower gears nice.

 

Lean spool is timer activated.
It will check if your rpm is above lean spool

If it's below then the values at antilag tables will be used ..
Then the rpm is again compared to value at &H1682 before the timer is activated

 

I thought the antilag tables were for actual antilag and are not used on the USDM Evos.

 

well....i found a instance where lean spool might be best disabled. I installed a AEM intake on my car for testing tonight....and found some interesting data.

With lean spool enabled, AFRs where not ideal for part throttle boosting. They were actually too rich in these load areas, still in closed loop. I disabled it and re-tuned and was able to get much better AFRs resulting in better part throttle boosting performance and faster spool up.

On a side note, i'm not too sure how i feel about this intake. As i knew they would, my IAT's went up ALOT..... But despite this, my AFR's were leaner because the intake is actually allowing more air into the engine. MAF hz went up slightly, but i'm not sure it's enough to negate the huge difference in IAT's. I'm not done with testing....but i will get to the bottom of it and make my conclusions.

CJ

 

I also noted what you are seeing with the AFr's. With the Lean spool disabled on partial throttle, the AFR's are easier to nail.

what IAT's are u seeing?

 

Seems to me that the leaner condition is not so much because of more air as because the relationship between the MAF signal and air flow goes out of calibration.

 

This is true. As a tuner, i am aware of the ill effects of the hard MAF pipe and irregular MAF hz readings....but, from my testing and logs, i didn't notice anything too crazy with regards to HZ from the MAF.....which really suprised me. Load is right where it was before, HZ went up slightly and AFR's went leaner, which all points to more air flow.

Of courese, the AEM intake is not the most aggresive intake, so a lot can be said for that alone. In my proffesional opinion, the AEM intake is a good replacement for the stock MAF pipe. As it does seem to play nice with the MAF sensor. BUT...and there is usually always a BUT, the high intake air temps i am seeing really bother me. IAT's rise fast @WOT....... I am seeing IAT's as high as 120degF on the street, in 70deg ambient air temps.....lol. This is while cruising. With the stock airbox using the stock cold air snorkel, IAT's where always a few degs at most above ambient at cruise, and got slightly cooler @WOT, as the intake sucked in cooler air from the front of the car.

I'm going to continue with testing and make my conclusion. I know there has been a lot of testing by certain vendors about their intakes......but what i'm mostly concerned with is IATs and how they may negate any pressure drop losses from using a hard pipe and open element filter over the stock aribox using just a drop in filter.

I hate to say this, but from what i am seeing, unless you can get cold air from the FRONT of the car and isolate the intake from heat soak.....the stock airbox w/a good drop in is going to be the best option. But, i'm not done yet, so we shall see.

CJ

 

That is high,,,,, in 90 Degree 100% humidty weather i see a max of 100-110' IAT with the HKS RS intake.