is it a bad idea to put the air filter directly on to the maf?

I have heard that it isn't good to place the filter directly on the maf either, I think about 8 straight inches should be good, they say if placed directly to the maf that you will get turbulence from the fans that disrupts the maf readings. But I run the stock box with a k&n so I don't know.

That's how I have mine? Still waiting on a tune from the performance shop, so I would like to see what others have to say as well. Never thought to ask, though I have an electric fan that has yet to turn on with the 3 row aluminum rad. up front, just tooling around the neighborhood?

I have mine directly off the MAF, but mine is in the fender wall so no problems.

AFAIK the best way to plumb a MAF is to have like 6-8 of straight/same dia. tubing leading to and after the MAF. having bends or diameter changes throws the accuracy off. the good thing is with a method to tune, you can tune it out.

say if a meter is flowtested at the manufacturer, with a straight pipe in front of the MAF. and then you put it on your car with a 90* bend right in front of the maf meter. the maf curve will be slightly off. if you have a tuner and can get on a dyno you can tune to your application and make it perfect again, there are alot of variables that affect the MAF's accuracy, the only surefire way to to actually tune the maf to the cars its actually going to be one, thats the preferred way.

another alternative is to have the meter flowtested and a new maf transfer generated, and have the tester try and simulate your air intake as best as possible. like if you know your going to have a bend right in front of the maf, the tester can clamp on a bend in front of the maf on the flow bench to more accuratly simulate your application. even still, the curve woul ideally still need tweaking on the car, like i said there are alot of variables that affect it all. even the air rushing under the car skews things a bit.

when its all said and done, i would bet the adaptive strategy would be able to correct for the error, thats assuming the MAF is close to begin with.
me personally i would never trust a "calirated" af to ever be accurate, to get things ACCURATE you need custom tuning. not knocking on the "calibrated" stuff, they do work and alot of peope have good luck, but if you were hook up a WB and monitor what the EEC is targeting, i would bet it would be suprising on how much error you might see.

with no WB or anything to see any of that, its hard to tell. an engine can run a wide range of AFRs and still run and act the same pretty much. a mustang could be running "great" at WOT but could be rather rich. for gasoline the ideal AFRs for WOT power are around 12.5-13 but black smoke doesnt really become present until the AFRs reaches the 9s or so. so you could be in the 10s in AFR, with no black smoke and the car could run awesome, but you could have some hidden power hiding and not even know it. like i said before, most of the time the calibrated stuff can get things close enough that CL correction and adaptive control can take care of things during CL/normal driving and will be good there. if the WOT is off, it will never be corrected, there is no sort of correction for WOT, since adaptive control uses the o2s to determine error and correct. stock o2s are useless for WOT so your stuck with whatever it runs, if you get a WB and means to tune, you can fix it.

when you have the tools and a WB etc to watch all that stuff, you can see even the smallest error and sometimes you can drive yourself nuts trying to fix it lol, when in all actuality its plenty good enough.

Mine is on the maf also. With the vortec in the way it leaves no room

ive always had my k&n's on the end of my maf's and I never have had anyidling issues or anything, however if you have a C&L you will have problems with this..

I have the Pro-M 75mm Bullet meter and what I have is the K&N panel filter, with the air silencer deleted. It probably has less cfm's than the cone filter that mounts on the maf, but it breaths fender air, not engine compartment air. The filter is also protected from fan wash. Also, air rushes into the fender area when the car is moving so the air kinda gets pushed into the filter box outlet. Personally, I'd rather have the panel filter with no air silencer, than a cone filter.