Changed intake after tune. Affect AFR?

**migoreng** · 23-04-2012 11:33 AM

My car was tuned with an Apexi AFC Neo a while ago. Back then I had the stock intake + K&N Panel filter.

I've just replaced it with a Prelude Type S intake + same K&N panel filter but whether or not it provides more power or not, I don't know. The Type S intake is noticably louder compared to stock. My butt dyno can not really notice much but maybe there's some improvement in engine responsiveness.

Generally if you install a better intake after at tune, how does that affect the AFR curve?
What if the intake was downgraded after tune? Does the opposite occur?

Adrian @ Toda tuned it for me. According to the dyno chart I'm running about 12.7-12.8 ratio all the way to redline...

**Touge Tom** · 23-04-2012 11:42 AM

in theory it should lean slightly? due to it allowing more flow. you should be closer to a 13 A/F-R now.

**curtis265** · 23-04-2012 11:47 AM

in for info.

given that the AFC neo 'adds or subtracts' fuel injection from the ECU's intended injection then it should adapt as well. I don't think it'll become problematic, but it won't run at 100%.

**infurNOS** · 23-04-2012 05:43 PM

If you add a better intake that actually flows better it may yield a little more power which will yield a leaner a/f. I doubt changing your intake will yield much more power.

If you were tuned at 12.8:1 you are good to go.

**trism** · 23-04-2012 06:46 PM

Yep, should learn the new flow after a tank of fuel or so.

Overa ll though, its probably not going to change power, just change the power band.

**migoreng** · 25-04-2012 03:16 PM

Thanks guys. I'll see how it goes for a week or two. After some more WOT, wow the Type S intake is louder after 4500rpm.
My Tanabe catback used to drown out the stock intake sound (removed resonator), now I can hear the intake again