# DIY: 4" MAF for C2 programming



## rado_speed (Oct 6, 2005)

*DIY: 4" MAF for C2 programming (56k... well who has that anyways...*

The weather sucked here in PA today so I couldnt work on my diesel mk1, so after somehow buying/recieving an obd2 4" MAF instead of an OBD1 from a vortexer last week, I decided to stop Fking around and make my own in my basment with a junk piece of 4" galvanized. Going for somthing like this one  Here 
I own no welder, so the only tools I used were:
Drill Press
Jigsaw
Dremel/sand paper/metal file
wire wheel
Circular saw with metal cutting blade

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First I measured the part of the maf sensor that I wanted to sit inside the cut, outlined it on the pipe, and drilled 4 large pilot holes in that area for the jig saw. After cutting:

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After a little work with the dremel and file, along with a few test fits:

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After a cut and some time with a wire wheel:

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Like I said it was trash piece of pipe, so I plan on painting it tomorrow, as well as picking up some silicone to seal it all up. All in all it will have cost me about 10 bucks.

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edit: ^^^my crappy digi makes it look out of round, but its not
_Modified by rado_speed at 5:37 PM 11-23-2006_
_Modified by rado_speed at 5:40 PM 11-23-2006_

_Modified by rado_speed at 5:42 PM 11-23-2006_


_Modified by rado_speed at 3:41 AM 11-24-2006_


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## fastslc (Sep 14, 1999)

*Re: DIY: 4" MAF for C2 programming (rado_speed)*

does not look 'centered' .. not sure if the air flow readings will be the same..
cool idea though


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## Buddha92SLC (Jul 22, 2001)

*Re: DIY: 4" MAF for C2 programming (rado_speed)*

Looks good. I took the pics in the link... or the one you modeled yours after. Mine is not centered either.
DO NOT USE SILICONE THOUGH. Pick yourself up some Marine Goop. That is actually the name of the stuff. It dries hard, unlike silicone. You don't want that sensor moving around at all. Marine Goop is water proof also, but dries hard.
Good luck!


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## 6pack (Apr 18, 2006)

cool. I used PVC and some "pvc sement" to make mine. whole 6 bucks. The sement actually "melts" the two peices together.


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## Jefnes3 (Aug 17, 2001)

*Re: DIY: 4" MAF for C2 programming (fastslc)*

Rado_speed: be sure to chat with Zach (original test car) to get specs on his intake pipe. You need to run a length of 4" pipe infront
of the sensor, ~how the sensor sees the air is critical to how
the ecu delivers the fuel.
nice work.

-Jeff


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## rado_speed (Oct 6, 2005)

*Re: (6pack)*

will pick up some Marine Goop tomorrow, http://****************.com/smile/emthup.gif good looking out
and I am more than familiar with similar Shoe Goop from back in my skating days








I had actually made one from a big piece of PVC pipe I had a few weeks ago, but I thought it was way too thick and it kept the sensor even farther from the center.Glad to see it might have worked though.
The inside looks almost exactly like Buddha's, it really is as far down as it can go due to the sides that wrap around the top. 
No problems with yours as of yet, Buddha??


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## rado_speed (Oct 6, 2005)

*Re: (rado_speed)*

thanks jeff, do you think I should make a 4" piece w/ nipple for my bov to dump into, or is 3" for that ok?


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## rickyrunamuk (Sep 13, 2004)

Rado_speed Please keep us updated on your progress, this is something I want to do as well


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## Buddha92SLC (Jul 22, 2001)

*Re: (rado_speed)*

The only problem I ever had with my car is when I removed the 4" 90" that my air filter is attached to before the custom maf housing. You WILL NOT just be able to put a filter on the end of that housing. Gonna have to run a 4" 90 like I did. Just make the hole bigger where the carbon canister is. Nothing like a turbo car sucking in nice cold air. IM me if you have more questions. I'll give you my cell # if you have any more questions.


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## Buddha92SLC (Jul 22, 2001)

*Re: (rado_speed)*

I just noticed your in E. PA. I'm in Allentown, we could even meet up so I can show you my car if need be.


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## mk2vrooom (Oct 15, 2003)

*Re: (Buddha92SLC)*

im also in north east PA if you need to check anything out?...i have the c2 4 inch on my car...


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## phatvw (Aug 29, 2001)

*Re: DIY: 4" MAF for C2 programming (Jefnes3)*


_Quote, originally posted by *Jefnes3* »_Rado_speed: be sure to chat with Zach (original test car) to get specs on his intake pipe. You need to run a length of 4" pipe infront
of the sensor, ~how the sensor sees the air is critical to how
the ecu delivers the fuel.
nice work.

-Jeff

Hey Jeff,
In the Kinetic kits with the 4" MAF, the filter just sticks right on the end of the MAF housing:








Would it be better to extend the pipe a few more inches in this application?


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## Jefnes3 (Aug 17, 2001)

*Re: DIY: 4" MAF for C2 programming (phatvw)*

I didn't think it would matter (dizzy vr6) but it DOES.
Zach and I spent ~weeks scratching our heads. 
The car went home running like a CHAMP. 
He did a little maintainece and moved
the airfilter to end of the MAF.... ran like CRAP.
Put back to ~original = runs like its supposed to.
You need to run the SAME set-up that I did making the tune.
Another note the mk4 12v MAF sensor is VERY different
than the Distributor VR6 MAF sensor. (Mk4 hot film vs hot wire)
Experiment all you like, just remember how to get back to ~original set-up.
-Jeff


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## rado_speed (Oct 6, 2005)

*Re: DIY: 4" MAF for C2 programming (Jefnes3)*

thanks for the replies buddha92slc and jefnes... I just got back from Cleaveland for the weekend, so I should be able to get everything finished tomorrow. Ill post the pics up as soon as I get them too.
and BUDDHA: yes If you can, I would like to take a look at your car sometime, just to get an idea of how the maf/ filter plumbing looks. Im guessing you just honed out the CC hole a little? I also have a few other questions for you.


_Modified by rado_speed at 5:16 PM 11-26-2006_


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## rado_speed (Oct 6, 2005)

*Re: DIY: 4" MAF for C2 programming (MK4futurayellowVR6)*

_Modified by rado_speed at 10:37 PM 11-30-2006_


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## rado_speed (Oct 6, 2005)

*Re: DIY: 4" MAF for C2 programming (mikemcnair)*

thanks for the props Mike!
Marine Goop is setting up as I type this, Ill get some pics up when its dry, and when my atp order comes in (hopefully this week)


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## VWeezly (Jul 5, 2005)

*Re: DIY: 4" MAF for C2 programming (rado_speed)*

That's sweet dude! Glad I could take the model off your hands







. I take it you're building a vrt?


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## rado_speed (Oct 6, 2005)

*Re: DIY: 4" MAF for C2 programming (VWeezly)*

yes sir I am.... 

almost 1 year in the making (doh!) but she's so close I can almost _taste_ the boost


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## VWeezly (Jul 5, 2005)

*Re: DIY: 4" MAF for C2 programming (rado_speed)*

I'v been searching for parts and researching for about a year. I'm modeling it after the Kinetics kit low boost and nonintercooled. What's your setup? If you want to take it to IM's that's cool... because it's not on topic with your post. http://****************.com/smile/emthup.gif


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## MigAce312 (Nov 22, 2002)

*Re: DIY: 4" MAF for C2 programming (Jefnes3)*


_Quote, originally posted by *Jefnes3* »_Rado_speed: be sure to chat with Zach (original test car) to get specs on his intake pipe. You need to run a length of 4" pipe infront
of the sensor, ~how the sensor sees the air is critical to how
the ecu delivers the fuel.
nice work.

-Jeff

How long a piece should be on there? My car didn't come with stock intake so I have no idea how far up the inatke track it was originally. Is this necessary even on MK3's?


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## brilliantyellowg60 (Aug 30, 2001)

*Re: DIY: 4" MAF for C2 programming (MigAce312)*

i was unaware C2 had sofware for as 4" 1-piece MAF


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## fastslc (Sep 14, 1999)

*Re: DIY: 4" MAF for C2 programming (brilliantyellowg60)*

^^ and 42 lb/hr @ 17 psi .. u slipping bad son !


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## AnotherA2VR6 (Jun 20, 2002)

*Re: DIY: 4" MAF for C2 programming (MigAce312)*

The OBD1 hot wire maf sensor is very sensitive to air flow disturbances, much more than the mk3 OBD2 style hot film maf or the mk4 style hot film maf. I made a 4" hot wire maf for my OBD1 and added a 8" length of 4" OD pipe before the maf with a cone filter at the end. This helped "straighten" the airflow and reduced fluctuations at idle, or low flow. I still have an issue at idle when the fans come on since my turbo intake is on the drivers side, i.e. mk4 style. I've built a separator between the cone filter and engine but the fans cause air disturbances at the filter making the maf signal rise and fall. The fix is to fabricate an "airbox" to block the airflow disturbances, (tested by making a cardboard airbox template, almost no fluctuations with this).
My advice is to make the pre-maf pipe as long as possible, (recommended to me by Jeff), and talk to the original test car owner who Jeff mentioned to get the exact specs.


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## fastslc (Sep 14, 1999)

*Re: DIY: 4" MAF for C2 programming (AnotherA2VR6)*

I've seen designs on Subarus STI's with larger MAFs where they incorporate a smaller diameter tube around the sensor and then your specified larger MAF around that
Smaller diameter tube = better idle since the air flow is slower
Larger diameter tube = higher RPM
d


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## Weak VR (Jun 26, 2006)

*Re: DIY: 4" MAF for C2 programming (fastslc)*

can someone explain to me the difference between and obd1 4in maf and on obd2 4in maf?


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## [email protected]! (Nov 7, 2006)

*Re: DIY: 4" MAF for C2 programming (Weak VR)*

do u need a 4" maf for a SCvr 8-14psi?


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## mikemcnair (Mar 28, 2003)

*Re: DIY: 4" MAF for C2 programming ([email protected]!)*

the difference in the obd1 and 2 maf is tthe way it reads the air. one does it with a really hot wire, and the other with foil(i believe). what happens in the more air that passes over it, the greater the change in temp of the wire, and the difference in resistance on the current to/from the wire. the ecu reads this, and alters your fuel curve. 
the wire is more sensative to turbulance in the air track. tha's why the longer distance from the filter is needed. it allows the turbulance from the filter to streighten itself out. 
i hoe that makes sense. 

_Quote, originally posted by *[email protected]!* »_do u need a 4" maf for a SCvr 8-14psi?

no, you will rarely have sustained 14psi. on a SC car you will peak there, but rarely. 
also, the need for a 4" is based on the fuel as well. you need 4" maf when you go 42 # inj or above. 
Jeff, chime in if i am wrong here http://****************.com/smile/emthup.gif


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## [email protected]! (Nov 7, 2006)

*Re: DIY: 4" MAF for C2 programming (mikemcnair)*

well jeff just told me ill need the 4" maf. thats running 36lb njectors...


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## mikemcnair (Mar 28, 2003)

*Re: DIY: 4" MAF for C2 programming ([email protected]!)*

i forget that you can run 36's. i can't on C2 so i immediately discard them as an option. sorry.


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## [email protected]! (Nov 7, 2006)

*Re: DIY: 4" MAF for C2 programming (mikemcnair)*

why cant you on c2? i cant run 30# on my 95 vr


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## mikemcnair (Mar 28, 2003)

*Re: DIY: 4" MAF for C2 programming ([email protected]!)*

() mikemcnair: do you make a 36# chip for OBD 1 Dizzy???????
() Jefnes3: not for dizzy cars. for dizzy i have 30 and 42#


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## [email protected]! (Nov 7, 2006)

*Re: DIY: 4" MAF for C2 programming (mikemcnair)*

well for the 36lb i guess ill need one of these maf's


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## Weak VR (Jun 26, 2006)

*Re: DIY: 4" MAF for C2 programming (mikemcnair)*


_Quote, originally posted by *mikemcnair* »_the difference in the obd1 and 2 maf is tthe way it reads the air. one does it with a really hot wire, and the other with foil(i believe). what happens in the more air that passes over it, the greater the change in temp of the wire, and the difference in resistance on the current to/from the wire. the ecu reads this, and alters your fuel curve. 
the wire is more sensative to turbulance in the air track. tha's why the longer distance from the filter is needed. it allows the turbulance from the filter to streighten itself out. 
i hoe that makes sense. 



well on the kinetics site it lists a 95mm maf, but thats only 3.75in....whats up with that?


_Modified by Weak VR at 1:28 AM 12-2-2006_


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## [email protected]! (Nov 7, 2006)

*Re: DIY: 4" MAF for C2 programming (Weak VR)*

yeah wtf is up with that?


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## AlexiGTIVR6 (Jul 21, 2000)

*Re: DIY: 4" MAF for C2 programming (Weak VR)*


_Quote, originally posted by *Weak VR* »_
well on the kinetics site it lists a 95mm maf, but thats only 3.75in....whats up with that?
_Modified by Weak VR at 1:28 AM 12-2-2006_

95mm is ID, The wall thickness is 1/8" so the OD = 4"


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## mikemcnair (Mar 28, 2003)

*Re: DIY: 4" MAF for C2 programming (AlexiGTIVR6)*

bump for recognition. http://****************.com/smile/emthup.gif


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