MAFT+ NA quicktune

[malice10985]

I just got a used MAFT + from JDRoth. It looks like an elephant chewed on it, but I am confident that it will work, despite the busted loooking casing and hot glue spots.


I have the final SCCA autocross of the season on sunday, and I would like to squeeze out a few extra NA horsepower.

From what I understand, If I lean out the fuel mixture on the base curve it will throw a code from being too lean. I was thinking of just slightly leaning out the WOT fuel curve. Is this advisable?

As far as ignition timing is concerned, How much timing advance can I get away with? I have a SLP CAI, Whisper lid, and pacesetter headers though a flowmaster 80 (like all that stuff actually matters here). I always use premium fuel, which locally is 91 octane. The car is a 1999 3.8v6 M5 maro.

I would autotap and figure all this stuff out for myself, but I don't have an autotap yet. It's coming soon. In the meantime, will someone give me some numbers to plug into this mystery box?

[John_D.]

Generally speaking, you can probably squeeze a little more power out, by adding 2 degrees of advance, and leaning the wot by 2%.

If you get too happy with the timing, the pcm will take it back out, so you're fairly safe there. Although it will take out more than necessary, so you would lose power, but at least you won't hurt the engine.

On leaning it out, that could hurt something. It's risky, without having a way to monitor the o2 readings. The pcm will not know if something is wrong, and will not protect you, because it doesn't monitor o2 readings at wot.

I'd suggest timing only, for now.

[malice10985]

JOHN D., I got a little more aggressive than what you recomended. I feel like a kid in a candy store.

Here is what I did:
MAF BASE 5%lean
MAF WOT no change

SPARK BASE 8 degrees advanced
SPARK WOT 6 degrees advanced

I have a A/F ratio gauge and it didn't show any noticable change when I leaned out the base fuel curve. I did notice that I got a few more miles out of my tank of gas.

As far as the spark goes... HOLY CRAP!!! THIS IS THE BEST MOD EVER!!! IT HAS SO MUCH SOTP FEEL!!!

I swear my car pulls like an LT1 up to 4600rpm. It has waaaay more power. At 4500-4600rpm though, it quickly runs out of steam and bogs really badly up to redline. My buddy sugested that I up the WOT fuel curve to compensate for the bog. I just did and I will test drive around and report back.

If that doesn't work, I guess I will just retard the WOT timing back 2 degrees. Any sugestions from you guys??

One more thing: a friend of mine told me that if I advanced the timing too much it could burn an intake valve. Is there any truth in this?

[malice10985]

Making the the WOT fuel curve $% rich took away the bog up to 5500rpm. I don't have any business reving past that anyways, so I am happy.

My GF said that all this extra power "rocks her Panties"!! [img]graemlins/omg.gif[/img]

[John_D.]

WOW!!

Sounds awesome. I'm running a maft currently, but have a maft+ in the garage. Maybe I need to throw that bad boy on there and try it out!

Rock on... [img]smile.gif[/img]

(that's a lot of advance - when running in hotter weather, I'd say monitor the knock retard and make sure everythings ok...)

[malice10985]

It hasn't been above 40 degrees since I installed my MAFT+. I will definatley retard the timing when the weather gets hotter.

I will order an autotap plugin next week so I can find out what is actually going on inside my engine. It sure feels like its working well.

Maybe I am just imagining things, but I think the exhaust note even sounds louder and more defined with the tuning done.