Do a before and after dyno and watch the power drop. Also that HKS intake SUCKS, I used to use one. Try this, take it off and look inside the pipe, see all that dirt in there? That is what the HKS foam POS is letting into you motor.

 

Changing the airbox changes the air flow characteristics through the MAF. Different airflows causes different feedback to the ECU.
The ECU cannot compensate if the MAF is "lying"; it takes what it says as gospel and adds the appropriate amount of fuel for that particaulr MAF reading.

If less air is getting in than the MAF "sees", you get a rich condition.
More more air gets in than the MAF "sees" ( as is the case with turbulent air ) you will go lean.
That's why the ECU has to be retrained, through some means.
It needs to be told that a certain voltage from the MAF that used to mean, say, 400 cfm now means 350 cfm.

 

Through all my experiences turbulence has always caused a decrease in airflow, never an increase.

 

Yes, it is a poor dirt filter but produces great air flow.
I always wash mine with every oil change, which is usually under 1500 miles.

 

where can we get these...."hi-flow filters" that just drop in for our car??

 

ISnt the new element filter disposable? Ur not supposed to wash them. I will replace mine every 6000 miles.

 

Im serious its easy to test

 

That is my point exactly. There is no actual increase or decrease of airflow.
It's not the volume, but how much of that air the MAF measures.

All things being equal ( boost, RPMs, etc. ), when you open the throttle, your engine is going to suck in the same amount of air
no matter what intake type you have.
It's how that air flows through the MAF that creates differences in the measured airflow.
Even the stock airbox creates its own unique flow characteristic.
The stock ECU is tuned to what the MAF says - this much volts means this much air volume.
You change the intake, you get different readings is all.
You have to adjust the ECU to the new readings.

I feel bad; we have hijacked ths thread. All the poor man wanted to know was how everybody liked his filter....

 

Great post I can never convey my thoughts on MAS sensor misreadings as well as this- perfect.

 

Ooops...mis-wording and explained it all wrong...sorry...but here is the correct scoop...

http://www.rallycars.com/Cars/bangbang.html


As for ARC air intake...I have one and love it...so nice choice...

Here is my question for MP5 & mikesevo...since the Evo runs rich as is...shouldn't you benifit from the leaned out condition caused..? From what I've heard alot of tuners tend to go for a leaner A/F mixture when they reprogram the ECUs to achieve more power. Since the Evo runs so rich shouldn't it be hard for it to go into an "over lean" condition unless you already adjusted your A/F mixture for a leaner setup..? After all alot of the people running Vent to Air BOVs haven't even had any serious lean conditions...lean yes...but nothing serious enough to cause the car to stall like many other types of cars...

Another thing...since the ARC is similar in shape to the stock box do you think this might limit or even cause no turbulence..? Just guessing...

What we all really need though as air intakes is that big box Ralliart uses in their cars, but rarely shows off...

 

VTA BOVs will cause RICH conditions due to the metered air being expelled.

Al has stated that the ARC box DOES cause lean conditions and det on the dyno! Your theory is that since the EVO runs so rich it can use some leaning out- My question to you is what is the error insuced and what AFR will be the result of the box? Also from what I have seen the induced error IS NOT a linear type error and usually varies in different load points on the band- Usually at the worst possible areas of peak VE. If someonw wishes to run these things they should be willing to spend the time and money to get on a dyno with the proper EM to tune the system properly- Uh Oh there just went your gains for a $500 box, see what Im getting at?

 

MP5 said it. The MAF readings for the air volume at each load point is not a linear curve, not even for the stock airbox.
Some load points may be close from intake to intake. Then others may be way off.
Whatever intake you have, when you get tuned to it, you stay with that intake.

 

Unless the factory box is a restriction in the first place, and creates resistance. (not that that is the case on an other wise stock car)

We are in agreement on how the systems works, I have no beef with that at all.

The thing that bothers me is the lean condition that is apparently caused from a simple filter change.
Just sounds very strange to me.
At this point I have to swallow it until I prove to my self that it is happening, or not happening (remember my personality flaw)

I am willing to bet that if the a/f meter were moved up the intake track somewhere the problem would go away.

BTW, I am sorry for hijacking the thread.
Tech discussions always get the best of me
I think the ARC box looks nice. Got any pictures of the inside?

aaron

 

Good points.
As far as restrictions go, given that the cross-sectional area of all the filters is about 4x the pipe it feeds,
everything but the dirtiest filters will allow about the same volume.

As for MAF position I agree. If there was a short piece of pipe between the filter box and the MAF that
stayed there with other filters, the flow characteristics would most likely be the same.

 

so if i have a super afc .. then i can run an aftermarket intake with no probs then since i can correct the a/f curve ?