Author Topic: MAF Conversion 2.0 ...let's get this figured out (Read 4111 times)

bmwman91 · « **on:** September 23, 2006, 01:39:38 PM »

Alright I got mad about the thing acting poorly as described in the attached text file (the original post before I edited it & wrote all this).

So, being pissed off, I did what I do best when mad. I had a crazy idea and ran with it. Lol, see the pic in post #2. Yes, yes it is a dirty sock I found in the garage.

So, with the sock-filter I took it around the block real quick. It no longer dies at ~2500RPM. It has a real crappy powerband all around, but it does not die. So, what does this mean?

It means the obviosu that I have sorta known all along about a MAF sensor. The thing is calibrated not only to the housing it sits in, but to the intake hoses & stuff sitting before it. When I bench-tested it, it was not on the OE airbox. Now, since there is a real short space between the airbox anf the MAF, and there is a square-to-round transition, I bet it just won't work right with the thing. I AM going to re-calibrate the MAF in hopes that this thing will actually work right in the airbox, but I have my doubts. Corss your fingers & pray to the fluid-mechanics gods.

So, whether or not it works with the OE airbox is one issue. The other is...some people who would want one do not use a factory airbox anymore. Since this MAF is seemingly really cranky about this stuff, it would behave differently (potentially) with a cone filter.

So, this brings me to the bad news. Say I get it working 100%. It might not be as cheap as I had hoped to produce. I might have to get custom ABS fittings made that are required to be used with this to ensure that every install works the same. I hope it does not come to this as I know everyone wants to have a cheap MAF converter available. I think I am about done messing with this for the weekend though...I have to get ready for my Half Dome hike...we are heading to Yosemite around midnight and starting the hike at ~3AM...you can carry a lot less water when hiking at night.

bmwman91 · « **Reply #1 on:** September 23, 2006, 01:43:14 PM »

Here is the joke-filter I rigged up. Getting mad DOES help every now & then.....

nickmpower · « **Reply #2 on:** September 23, 2006, 01:44:01 PM »

are u sure the maf is good?

bmwman91 · « **Reply #3 on:** September 23, 2006, 02:18:24 PM »

Yeah I am sure it is. More testing has to be done now....grrrr.

Stupid fluid. Why can't you just flow into the sensor the same way regardless of what is in front of it!!!? Lol, I heard somewhere that Einstein or someone said that if they were allowed to ask god 2 questions they would be:
1) What is the meaning of life?
2) Why turbulence?

Euro Nation · « **Reply #4 on:** September 23, 2006, 04:16:32 PM »

I love you too

Ramblin MAn · « **Reply #5 on:** September 23, 2006, 04:59:24 PM »

You're description of the stall/ power loss sounds a lot like what I was experiencing in my other post.

Does anyone have the resistance values of the stock AFM at closed half and wide open? I'm still trying to figure out what the curve is supposed to look like. Both AFMs I have do a bell shape, but both may be bad for all I know.

Gizmo318i · « **Reply #6 on:** September 23, 2006, 07:20:08 PM »

I was told this by my tuner, you need a bit of pipe length (ram tube) before the MAF to straighten the airflow so you get accurate readings over the hotwire sensor. If your intake length is too short/ non-existant then you will have turbulent airflow over the hotwire sensor, giving inconsistant values. ie, car idles and runs rough.

bmwman91 · « **Reply #7 on:** September 25, 2006, 10:18:45 AM »

Quote from: Gizmo318i

I was told this by my tuner, you need a bit of pipe length (ram tube) before the MAF to straighten the airflow so you get accurate readings over the hotwire sensor. If your intake length is too short/ non-existant then you will have turbulent airflow over the hotwire sensor, giving inconsistant values. ie, car idles and runs rough.

Yes, this is exactly what I was thinking might be going on. Considering the car runs vastly different whenever I change a physical parameter (obstructions in MAF's inlet path), I would say this is the next logical way to investigate. I will see if I can source an ABS plastic 'horn' like the one in Euro Nation's graciously provided pic. Hell, just for around-the-block testing purposes I can make a test rig from cardboard.

Quote from: Euro Nation

I love you too

Does your wife know yet? :p
Thanks for the pic man, it actually helps me a lot in figuring out my next move.