i removed the screen last night to see if it was a restriction in limiting my boost....i picked up about 1 psi. but as i remembered, the idle got shitty..hunting all over...not all the time...seemed to clear up once i drove it a bit....blm's went up into the 140's....wideband off the high end at idle...way lean...why does this happen? the car did feel like it pulled harder once it spooled...
stock maf and screen removal ?
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m233roller
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You say you removed THE screen? You have to have one in there, that's why your getting all the funny stuff.
did you get my pm?
i thought Eric's chips were open loop at idle?
mikestertwo
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Removing the screen upsets the calibration of the MAF. The idea of the screens is to give a laminar flow of air across the sensing elements in the MAF. Removing the screens creates air turbulance changing the MAF calibration causing fueling to be off.
I got your pm. Leaving it out won't hurt anything under power as long as it's not leaning it from increased mass flow. It's likely picked up a decent amount of mass flow without the screen. Looking at a/f and adding fuel will get you where you need to be. At this point you can add additional spring pressure to your wastegate actuator. You need a chip burned for no screens or replace the mafs with a larger aftermarket one.
To give you an idea of how much the MAF is a restriction. Steve Yaklin, developer of a MAFless set up, told me he saw about a tenth of a second gain in the 1/4 going to his MAFless set up on a mid 10 sec car. If you are going through the trouble of getting a new chip might as well go the TurboTweak SD chip route. At lease you wont have to deal with dead MAFs either. I had 2 MAFS die so I went the SD route a few years ago. hard to say if the car is any faster but I am glad it is gone. 
so i am not imagining that the car felt a little quicker? it did lean out from 11.2s to 11.7s...i will add some fuel....as i already said, my wg rod is as tight as it will go.....
Sweet6 said:To give you an idea of how much the MAF is a restriction. Steve Yaklin, developer of a MAFless set up, told me he saw about a tenth of a second gain in the 1/4 going to his MAFless set up on a mid 10 sec car. If you are going through the trouble of getting a new chip might as well go the TurboTweak SD chip route. At lease you wont have to deal with dead MAFs either. I had 2 MAFS die so I went the SD route a few years ago. hard to say if the car is any faster but I am glad it is gone.
With a 60-1 it was more than a tenth of a second in my experience. I couldn't get more than 24-25psi with the wastegate closed. After removal I was able to get 30+psi on the same engine. More like 3-4 tenths. I was working a smaller turbo a lot harder though so I showed a larger gain because I was boost limited by compressor inlet restriction. You actually chop off a large portion of a compressor map by having excessive Vacuum at the inlet. Most Compressor maps assume about .5" Vacuum. If you have 4" vacuum there you are cutting your balls off if trying to use a small compressor to get it done. Turning it back to 24-25psi on the chassis dyno was only showing about 12whp peak over the stock MAF though it picked up power everywhere. Just not much. Spool was drastically improved. Backpressure actually drops when removing inlet restriction also because it takes less energy to drive the turbine so there is some gain in mass flow and more opportunity to fill the cylinder because of it. That is likely where my power gain was on the back to back test at the same boost pressure.
trbojo said:
That's probably a 40hp increase. There's definitley a mass flow increase there and our air is terrible lately. Hot and humid. In dry
60* sea level air you would see a lot more mass flow and a lot more energy to drive the turbine.
i may have been confusing in my post...i was referring to afr's, not times....but if you understood me correct, will i lose that increase when i add fuel to bring the afr back where it should be?
You are leaner because the engine is moving a higher mass flow and the fueling is the same as it was when it was flowing less. You will probably lose a few hp correcting it back to your old target. it's too lean the way it is.
