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Old 05-16-2000, 04:13 PM   #1
Overtime
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Member#: 1346
Join Date: Apr 2000
Post 99 Intake...any good solutions?

From what I can tell (and it ain't much, since I'm not a tech forum guy) the Weapon R intake offered for the 99 is just trouble waiting to happen. Is there a good solution to this or is the MAF always going to be causing problems?

Thanks-I'm considering buying an intake and I want to know if there's any way to get around the MY99 problems.
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Old 05-16-2000, 04:19 PM   #2
Strepto
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Join Date: Sep 1999
Location: San Antonio, TX
Vehicle:
2001 Arctic White
Camaro SS #1800

Post

I've had my JC Sports intake for a good 8K miles. My MAF is yet to blow. The streets out here are crap and if the MAF could get vibrations it would be here, but I haven't had a problem. I've made a few road trips as well, again with no problems.

(note: everyone knows the problems with JC Sports as a company. there's no reason to bash them now. I'm just saying it's a good product)
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Old 05-16-2000, 04:26 PM   #3
NYRS
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Location: Levittown, NY, USA
Post

I've also had the JC Sports intake on my 99' for about 12k now without a blown MAF. The only problem I get is sucking in some water in really bad rain storms or when I go through a nasty puddle, but as soon as everything dries its back to normal.
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Old 05-16-2000, 06:06 PM   #4
rjones
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Location: Cambridge, MA
Vehicle:
2003 wrx wagon
silver

Post

I'm about to fiddle with my MY 99 induction as well. I'm not as concerned with blowing out the MAF as I am with the lean condition. IS there anyone running a jc/weapon r without a fuel controller. I'd like to avoid engine damage...

rj
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Old 05-17-2000, 05:48 AM   #5
Scooter
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Location: Farmington,CT,USA
Post

As I've posted before, the MY99 Hot film mass air flow sensor is made by Bosch. In a patent covering improvements to the design of this MAF (or HFM as it is known on some other BBs), Bosch specifically talks about the errors that can occur in the presence of intake pulses, especially at higher RPM. The improvements supposedly reduce the MAF's sensitivity to these pulses.

With the older design, like on the MY99, the car manufacturer had to design intake features to reduce the strength of these pulses in order to prevent errors. On the MY99, the "plenum" just behind the throttle body and the dead ended tube (helmholtz resonator)sticking off the intake tubing near the MAF are two such features. Any intake mod that involves removing either of those two features will allow stronger pulses to reach the MAF. This could, and actually has been shown to result in errors in the mass flow rate reading at certain RPMs.

I feel a good solution to this problem may be finding a MAF with the above mentioned improvements that is swappable with the MY99 unit. Does one exist? I'm not sure yet. I have seen a lot of pictures of engine bays with MAFs that look just like our unit (mostly on newer BMWs).

What would need to be done to find a swappable unit? Well first off, the output voltage versus mass flow rate curve for the MY99 unit needs to be established. This can be obtained with either just a OBD II Scan tool or Scan tool and DDM. If the Scan Tool can display both the MAF's output voltage and mass flow rate, then that's all one needs. If the Scan tool can't display the output voltage, then you'll need a DDM to measure that. (Note: I have yet to do this myself, because I presently don't have a laptop to run the Scan tool software on.)

The next step would be to search out MAFs on MY2000 cars that have a Bosch MAF with the same connector and the same Inner diameter as ours. Then you would have to repeat the proceedure above to establish the voltage versus flow rate curve. If the two curves match, we have a winner.

Of course, it would be a lot simpler if SOA would just provide an improved version through their dealers parts departments. But we all know how proactive SOA is.

Oh yeah, the other possibility would be to modify the existing MAF with the improvements. Either buy a second one or modify the one on your car.

Now, I'm not saying this will definitely solve the problems with MY99s, but I think it is at least worth experimenting with. Hot film MAFs can't be all that bad if companies like BMW are using them on their top of the line cars like the M3, M5, Z8(which actually has two), etc., etc..



[This message has been edited by Scooter (edited May 17, 2000).]
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Old 05-17-2000, 06:52 AM   #6
Subie Gal
GC84Ever
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Chapter/Region: NWIC
Location: WA
Vehicle:
1970 FF-1 & '70 Van
02 WRX/01 RS

Post

I've had the WeaponR on my 99 since last Aug and have had no problems at all...

The MAF issues were thought to be caused by vibration - too much play after installing the intake. I used a bracket to support/brace the MAF - i bolted the bracket onto the wheel well and have never had a single problem.

I don't know if it's the brand of intake, or how you mount it that's causing the problems. I can just relay what I have done and it's worked for me.

j.
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Old 05-17-2000, 07:03 AM   #7
mpaone
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Chapter/Region: South East
Location: Alfretter Geeoja
Vehicle:
2012 Geeteeeye
and 71' VW Gulf Beetle

Question

In the last issue of SCC, I saw an ad for an air filter that was supposed to reduce intake pulses. They stated that this would help with cars that have MAS sensors. It showed a picture of one and it was in an RS engine compartment. The web address is www.monsterflow.com. Anyone have one of these?
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Old 05-17-2000, 07:18 AM   #8
Eric
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Chapter/Region: MAIC
Location: Charlotte Hall, Maryland, USA
Vehicle:
1999 Impretza 2.5
silver

Post

I have every thing from the sensor out replaced with a MRT setup. I came with a very strong brace that the filter mounts to. It really supports the sensor. But I left the rest, all the stock stuff from sensor to throttle body is intact.

Its been about 10k or more and no problems. Its a oiled foam unifilter element, and stays very clean with my homemade heat shield. Im about to make a new post regarding my next project with the intake.

Eric
Silver 99 RS
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Old 05-17-2000, 10:03 AM   #9
Scooter
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Member#: 75
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Location: Farmington,CT,USA
Post

mpaone,
There was a previous post/topic on the Monster flow unit. I believe the picture of the unit mounted in an RS belongs to a member of the iClub. (Sorry, I forgot your name. To lazy to do a search)

Anyhow, I believe the Monster flow unit is claimed to reduce turbulance at the opening of the intake system, not pulses. With my knowledge of Fluid dynamics, I can see how the unit would reduce entrance turbulance, but I don't see how it could reduce the strength of pulses that originate in the intake ports and propogate back through the system to the MAF.

Subie Gal and Eric,
When you say no problems, do you mean no failures or do you mean you're not running leaner at any RPM band than you did before the mod? Though these two problems maybe related, I don't think it has been proven that the same phenomenon that causes the MY99 MAF to misread is the same one that causes it to fail.
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Old 05-17-2000, 10:08 AM   #10
SubePwr
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Member#: 140
Join Date: Aug 1999
Location: Seoul South Korea
Vehicle:
1999 RS 2.5
Blue

Exclamation

I have had my Minnim(SP?)on my99 for over 18000 miles and no prob.

Now if I could only get the car back from Sube, they have had it for over 3 weeks for clutch, flywheel, and pressure plate replacement. arrrrrrrrrrr buttheads...

Jim
Subeless in OKC
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Old 05-17-2000, 01:13 PM   #11
Overtime
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Exclamation

So it seems to me like the vibration while not actually causing the problem is where the cure will lie?

Sounds pretty good to me. I'm looking forward to the relatively cheap NA power an intake gives you...plus the sound and the rush and all.

Thanks for taking the time to reply, all.
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Old 05-17-2000, 09:23 PM   #12
Peaty
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2010 Legacy 3.6R Lim
Azurite Blue Pearl

Arrow

I built my own intake and kept the rear airbox. After reading about the pulsing problem I thought I'd better leave that there. I did put a gasket in place of the filter that was there though. I also mounted the MAF on there so it dosen't vibrate. I had it in for around 6K miles and no MAF problems so far. I don't seem to have any flat spots either all the way to the rev limiter. I have some info and pics here:
http://www.azscooby.freeservers.com/

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Old 05-17-2000, 09:57 PM   #13
biomed_eng_2000
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Location: San Diego
Post

Scooter,
I talked with the guys at MonsterFlow and for the MY99 they recommended that the stock plenum above the throttle body be retained along with the short dead end tube that sticks out of the main intake tube. They make no claim concerning pulse reduction.

[This message has been edited by biomed_eng_2000 (edited May 17, 2000).]
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Old 05-18-2000, 05:05 AM   #14
Scooter
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Member#: 75
Join Date: Jul 1999
Location: Farmington,CT,USA
Post

Thanks biomed, that's what I thought.

Like Eric stated, he kept everything from the MAF to the throttle body intact and hasn't had any problems. However, others have stated that they removed some or all of the intake plumbing between the MAF and throttle body and have experienced no problems as well. I have some theories on that, but they would take too long to explain and would be getting of topic.

For now, you can go to the AZ Scooby web site listed in Peaty's post above and take a look at the failed MAF pictures. The pictures aren't the greatest, but they were the best I could do at the time. I hope to have better ones soon. Also, below is a link to the US patent that Bosch has on the improvemnets to the MAF design. You'll need to get the right plug-ins to view the images. Once you can view the images you'll se how they compare to the pictures of the MAF I took apart.
http://164.195.1 00.11/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=/netahtml/srchnum.htm&r=1&f=G&l=50&s1='5948975'.WKU.&OS=PN/5948975&RS=PN/5948975

Or just go to this site instead. http://www.patents.ibm.com/cgi-bin/v...d/US05948975__



[This message has been edited by Scooter (edited May 18, 2000).]
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Old 05-18-2000, 06:22 AM   #15
mpaone
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Chapter/Region: South East
Location: Alfretter Geeoja
Vehicle:
2012 Geeteeeye
and 71' VW Gulf Beetle

Post

I remember this being covered before but... would leaving the stock tubing and rear "plenium" intact (and adding a high flow intake) remove the necessity for a fuel computer in the 99's?
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