Anyone who has made their own MAF to airbox connection for home brew might want to see this.........

JasonS4+Festicle · 11-17-2005, 08:17 AM

So, I'm running home brew stage III. Was using an 85mm MAF from VAST mated to an open element filter. Anyone that has used a set-up like this knows it is a bit louder than using a stock airbox. I was hoping to get rid of the noise so went back to the same MAF housing mated to a stock airbox top.

Apprently, the way the MAF housing is mated makes a big difference in MAF readings and consequently fueling.

So, I put the MAF to stock box in and immediately was running rich - like 10.0 on my wideband (that's as rich as it goes).

Tried pulling fuel with Lemmi - no better.

Mike2KS4 suggested I change how the MAF was mated since any turbulent airflow can really mess things up.

Here are some before pics:

Again A/F pinned at 10.0 on my wideband. This is with greentops and -22% primary fuel pulled.

Notice the blue epoxy areas that seem to cause a tiny narrowing before the MAF.

Thanks to WindyCityS4 for his help and Mike2kS4 for his suggestions, as well as Piggie who mentioned opening up this area. I dremmeled away (and used a die grinder) some of the extra "stuff". I then used an epoxy paste to fill any new holes I created.

The result:

A/F ratio now mid 11's to 12's. No other changes - just made sure the opening in front of the MAF had no areas that could cause turbulence.

Our MAF sensors are very sensative and even this little bit of abnormal flow was apparently causing bad readings.

My g/s went DOWN after opening up that area. I think I was getting a falsely elevated airflow reading causing my car to give more fuel than it needed.

Hopefully, this will help anyone who might be having odd fuel issues.

~~ModifiedA4~~ · 11-17-2005, 08:24 AM

Arcteryx::Stock Rods · 11-17-2005, 08:25 AM

2000s4biturbo::Uli · 11-17-2005, 08:28 AM

Audeye A6 · 11-17-2005, 08:30 AM

lemieux@curbside · 11-17-2005, 08:36 AM

and build jb weld all around it .. it would be perfect if you can find a bell mouth 4"

i was thinking about doing that for the next summer.
btw i have the exact same MAF.

~~ModifiedA4~~ · 11-17-2005, 08:37 AM

i wonder if a short velocity stack at the maf/airbox junction would be a good idea.

WindyCityS4 · 11-17-2005, 08:38 AM

Todd/A.W.E. · 11-17-2005, 08:41 AM

our MAF housing design.

That is why the straightener was a necessary part for us.

The turbulence is from the airbox, not from the "step" in our housing.

Captain Matt, I be · 11-17-2005, 08:44 AM

11-17-2005, 08:17 AM	#1
JasonS4+Festicle AudiWorld Super User Garage is empty, add now Join Date: May 2002 Posts: 7,229	Anyone who has made their own MAF to airbox connection for home brew might want to see this......... So, I'm running home brew stage III. Was using an 85mm MAF from VAST mated to an open element filter. Anyone that has used a set-up like this knows it is a bit louder than using a stock airbox. I was hoping to get rid of the noise so went back to the same MAF housing mated to a stock airbox top. Apprently, the way the MAF housing is mated makes a big difference in MAF readings and consequently fueling. So, I put the MAF to stock box in and immediately was running rich - like 10.0 on my wideband (that's as rich as it goes). Tried pulling fuel with Lemmi - no better. Mike2KS4 suggested I change how the MAF was mated since any turbulent airflow can really mess things up. Here are some before pics: Again A/F pinned at 10.0 on my wideband. This is with greentops and -22% primary fuel pulled. Notice the blue epoxy areas that seem to cause a tiny narrowing before the MAF. Thanks to WindyCityS4 for his help and Mike2kS4 for his suggestions, as well as Piggie who mentioned opening up this area. I dremmeled away (and used a die grinder) some of the extra "stuff". I then used an epoxy paste to fill any new holes I created. The result: A/F ratio now mid 11's to 12's. No other changes - just made sure the opening in front of the MAF had no areas that could cause turbulence. Our MAF sensors are very sensative and even this little bit of abnormal flow was apparently causing bad readings. My g/s went DOWN after opening up that area. I think I was getting a falsely elevated airflow reading causing my car to give more fuel than it needed. Hopefully, this will help anyone who might be having odd fuel issues.

11-17-2005, 08:24 AM	#2
~~ModifiedA4~~ Banned Garage is empty, add now Join Date: Mar 2000 Posts: 34,550	pics work now...(edited)

11-17-2005, 08:25 AM	#3
Arcteryx::Stock Rods AudiWorld Super User Garage is empty, add now Join Date: Feb 2004 Posts: 8,200	thanks for the post....when/if i get my car, i'll make a mental note to check it out. __________________ Bored 2.8/9.1CR JE Pistons/034 Rods/RS4 Heads KO4's Port Polished/VAST Meth Injection RS4 Intake Manifold/Throttle Body X-1 Intake/ER IC's ASP Exhaust Heads to Tips Clutchmaster Stage IV with LWFW STaSIS Ohlins 700/800 AWE DTS Alcons 355 6 Piston BBK

11-17-2005, 08:28 AM	#4
2000s4biturbo::Uli Elder Member Garage is empty, add now Join Date: Nov 2003 Posts: 14,238	is it glued directly to the maf? __________________ MY BABIES a.k.a. CARS you want the best for your car? tell him i sent you. FATS database NOT stock ;^P nogaro 6mt my00, casa 6mt my01.5

11-17-2005, 08:30 AM	#5
Audeye A6 AudiWorld Super User Garage is empty, add now Join Date: Dec 2003 Posts: 4,246	pictures worky now. __________________ 2001 2.7T / 6spd / Cold Weather Pkg. / Premium Pkg. EPL Custom Tuned Stage III / 93 Oct Bilstein-HD / B&G Sport Coils / H-Sports KO4/997 Hybrids, EV14 Inj, ASP MAF Vast Kevlar Clutch,RS4 PP & Throwout bearing Autospeed Trans. stabilizer bar AWE/McNeil Downpipes/graphite rapped AWE/McNeil Intercoolers APR exhaust/snub mount Port/Polished/Ceramic coat exh. mani's JHM short shifter Hardwired/stealth V1

11-17-2005, 08:36 AM	#6
lemieux@curbside AudiWorld Super User Garage is empty, add now Join Date: Dec 2002 Posts: 17,781	better find a round 4" pipe and drive through the airbox (let it stick inside 1-2 inches) and build jb weld all around it .. it would be perfect if you can find a bell mouth 4" i was thinking about doing that for the next summer. btw i have the exact same MAF. __________________ ************************************************ ************************************* "it's a B5 S4 ,it may break down, but its far enough ahead, by the time its fixed, you still haven't caught up." -best line i've heard AUDI B5 S4 detail info (pdf file) that everyone should read and have saved on his computer AUDI B5 RS4 study guide detail info (pdf file) FATS database VAG-COM LOCATOR ASP Hands down the "BESTEST" tuner out there.

11-17-2005, 08:37 AM	#7
~~ModifiedA4~~ Banned Garage is empty, add now Join Date: Mar 2000 Posts: 34,550	good info... i wonder if a short velocity stack at the maf/airbox junction would be a good idea.

11-17-2005, 08:38 AM	#8
WindyCityS4 AudiWorld Super User Garage is empty, add now Join Date: Mar 2003 Posts: 7,553	The MAF housing is "glued" to the airbox, but the MAF sensor can be removed. __________________ In a world of constant change, it is the learners that shall inherit the future. For the learned soon find themselves capable of living in a world that no longer exists. Autobahn Country Club (North, South, combined), Blackhawk Farms, Gingerman, Grattan, Mid-Ohio, Putnam Park, Road America, Sears Point, Thunderhill and "The Ring"

11-17-2005, 08:41 AM	#9
Todd/A.W.E. Member Garage is empty, add now Join Date: Mar 2000 Posts: 4,109	Maybe now people will start to believe that the MAF issues we had during development were NOT from our MAF housing design. That is why the straightener was a necessary part for us. The turbulence is from the airbox, not from the "step" in our housing. __________________ Todd Sager President A.W.E. Tuning Order line: 1-888-565-2257 Tech line: 215-658-1670

11-17-2005, 08:44 AM	#10
Captain Matt, I be AudiWorld Expert Garage is empty, add now Join Date: Oct 2001 Posts: 32,081	i have some interesting ideas about rigging something up, i need to find a spare airbox cheap. __________________ Support Innovation for the B5 Platform - www.autospeedperformance.com www.vastperformance.com B5 S4 Forum Cliff's Notes B5 S4 RNS-E Nav+ Installation

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