Posted about my next mod on some local boards and this is what someone had to say...

Any thoughts, I'd love to give him some info that he wasn't aware of.


"Here's my experience with messing with MAF's.

On my 05 STI I installed a GPMoto short ram intake which had a housing for the MAF. The housing was of a larger diameter than stock, Allowing more flow at a lower reading. This increased power, throttle response etc.

Why though? Was it more flow? no. It was because by increasing the housing diameter you're allowing the same amount of air to be pulled in as before but now your MAF reading is lower. Your MAF readings is a voltage signal, indicating how much air is being pulled in. By increasing the size you increase the "ceiling" for the amount of air you can read. Meaning, if before you maxed out your MAF voltage (5 volts) at 450 hp, now you can max it out at 500.

However, since you're not changing anything but the housing you're "tricking" the ECU into reading less air. As a result, your fuel is less. Now, since your fuel is less and your airflow is the same, your AFR's are leaner. This is where you're temporarily making power.

Now, OBD2 systems are going to take into account several things. One of which is your o2 reading. The computer will realized the fuel trim calculations are not correct and it will slowly adjust fuel until it's happy. This takes time.

Second of which will be your knock readings. As you lean out the car and leave the timing alone, you're throwing off the "equalibrium" the ECU is currently in. It's going to read more knock and have to retard your timing.

There goes your power. Eventually your power levels, throttle response, etc. will be back to what it was previously, as the ECU learns. However, in the learning process your ****'s going to be all outta whack.

The moral of the story is, messing with MAF housing diameter should be done for one reason only. Increasing the airflow ceiling for HP applications that extend beyond the stock MAF's capabilities. And Engine Management should ALWAYS accompany such a change."

 

delta in airflow - it balances the air-fuel ratio through hardware design (no change in programming needed).

 

What do you mean by hardware design?

 

The MAF diameter and FPR (4-bar) design are hardware, programming (which isn't needed) is software.

 

I really don't understand what you're saying.

I'd like to provide some info to this guy as to why it won't do what he says, but from what I'm reading... maybe he's right.

 

the guy (your acquaintance) is correct in his analysis, thus the need for *either* a hardware or a software correction.

 

... and the **** uses a hardware correction, with the REQUIRED 4-bar regulator.

 

By only increasing the air flow by fooling the MAF he is totally correct. Eventually the computer will correct the mixture. When you buy the **** you should get the 4 bar FPR (fuel pressure regulator). This also increases the amount of fuel per pulse of the injector. The computer will fine tune the mix just as if it was stock but we will (mine is on the way I hope) be burning more fuel with the accompaning air.

 

or an adjustable.

 

That's spot on.