WTB: RPI scoop

[JJZ4MR]

I'm curious about this OBDII data mpathic refers to. Where would I see these "wonky MAF readings" My car is straight up stock, except for new mods mentioned in post # 20

[mpathic]

Sounds like someone else isn't talking from first hand experience.

You will get "wonky" MAF readings if you remove the little air horn from the top of the airbox. This is the horn that is just in front of the screens and MAF sensor.
KEEP the little inlet horn because its essential for air velocity at low RPM so that you still get an even enough air flow across the MAF sensor at low/mid RPM to avoid rough or uneven throttle response and to pass California smog.

There are no adverse consequences of remove the screen that comes between that little inlet horn and the MAF sensor. The screen definitely blocks air flow versus a wide open circle.

The final version 231hp M54 engines as used on the E60 use the same air filter and nearly identical airbox, _without a screen in front of the MAF sensor. These also have a one pieces, straighter, less accordion shaped intake air boot. Otherwise, they're the same 3.0 liters that were 225hp on older models that had MAF screens and two piece rubber accordion air boots. The 235hp ZHP 3.0 liter engines in the E46 had the older breathing and smaller air box and air filter, with bigger cams.

OBDII data:
MAF flow data always tells the truth, not subject to internet hearsay.
The OBDII data stream can be read and logged by numerous available devices. I like the Innovate OT2 to send a wify to an iPad that runs the Innovate app.
For in place more advanced diagnosis and module resets, and for fun to see all of what's going on in the vehicle electronics, I suggest the Foxwell (no commercial connection) unit as sold by several EBay and Amazon vendors.
I log MAF flow across the rev range to see what difference intake and exhaust changes have.
Rule of thumb is that power increase is 1/2 the intake air flow increase. So 10% MAF flow increase = 5% power increase.
Remember that air temperature changes air density, so MAF readings will vary in hotter or colder air.
hth, Barry

[JJZ4MR]

Very interesting stuff here. Trying to get to the bottom of this good vs bad mod. Also trying to tie info together from this post and the MAF post. Still not 100% clear on the removal of the air box baffle ? Is it a carbon fiber baffle that is in the top half of the air box ? I need some pics. on the three pieces you are recommended be removed for a gain of 23 HP for "free" I,ve researched the MAF itself and feel I've got a pretty good understanding of it now. I looked at all the various options of aFe filters flat VS conical. aFe has SO MANY options, on the flat OE style they offer 4 different that are for use in the Z4M in the type of material that you can order when purchasing. Claims of increased HP/Flow/Torque stated are comparing thiers to a paper filter, which who has a paper filter...no one...am I right on this ?

[mpathic]

To help visualize:
Remove #10 and optionally #12 on
http://www.realoem.com/bmw/enUS/show...diagId=13_1174
You can get at #10 by removing the left grill and giving #10 a hard pull and twist.
#12 comes out by removing the bottom section of the airbox. Also dump out the sand and pebbles that accumulate in that bottom section.
Though not a performance advantage, removing #12 will help prevent much of that sand and pebble buildup.

Inside the top part of #1,
First remove the paper baffle that's inside a plastic frame that's snapped into the top part. This is the restrictor plate that serves no use purpose except to restrict power output.
Then notice the little stubby air horn, screwed into the airbox cover.
Unscrew the air horn with a T30? socket. Then pop out the screen. Then screw air horn back in.

The RPI piece goes on in place of #10, but removing #10 takes away the big restriction.
Removing #12 will get out a bit more pleasing intake sound, with possibly 1% more air flow at higher rpms. Along with stopping some of the pebbles and sand from building up in the bottom of the airbox.

Note:
Be CAREFUL when working around the MAF sensor. Or remove it from the airbox before removing the baffle and screen.
While you have access to it, clean the MAF sensor with CRC brand MAF sensor cleaner. I clean my air filter and MAF sensor with each oil change.
hth

Originally Posted by JJZ4MR

Very interesting stuff here. Trying to get to the bottom of this good vs bad mod. Also trying to tie info together from this post and the MAF post. Still not 100% clear on the removal of the air box baffle ? Is it a carbon fiber baffle that is in the top half of the air box ? I need some pics. on the three pieces you are recommended be removed for a gain of 23 HP for "free" I,ve researched the MAF itself and feel I've got a pretty good understanding of it now. I looked at all the various options of aFe filters flat VS conical. aFe has SO MANY options, on the flat OE style they offer 4 different that are for use in the Z4M in the type of material that you can order when purchasing. Claims of increased HP/Flow/Torque stated are comparing thiers to a paper filter, which who has a paper filter...no one...am I right on this ?

[JJZ4MR]

Thanks for the clarified explanation. I'm pretty OCD. I'm going to get under the hood, match the diagram with the car. I like debate on these forums, especially when two posters have differences an there is PROOF one is right and one is wrong. As long as it's all constructive and helps others, even years down the road.

mpathic, really appreciate your input on this subject. You certainly seem to have all the answers. I'm just surprised this is not more widely known and discussed by others, or perhaps I've just not found it.