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Old 10-20-2010, 10:12 PM   #1376
teslamaster
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Quote:
Originally Posted by RaceFaceXC View Post
The most effective means would be welding on the ports. I get the idea that welding isn't an option for you to do yourself, though.

An easy and probably still satisfactory means could be using riv nuts of the appropriate size. 1/4" should be about perfect. Use aluminum or stainless steel. other steels may cause corrosion issues with the alum intake pipe after a relatively short period of time, not to mention that they will rust.

These are Riv Nuts
Avoid using stainless with the aluminum pipe due to galvanic corrosion.

If you know someone who can TIG aluminum it wouldn't take them long to do it for you.
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Old 10-21-2010, 08:29 PM   #1377
wmdoucette
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Drilled holes, ran in shortend pipe thread nipples, epoxied... hasn't leaked in a year.
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Old 10-27-2010, 03:23 PM   #1378
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Hey everyone,
Im new to the forum and pretty new to Subaru. Apologies if this has been answered already but I don't have the time to read through 56 pages...

I own a 2002 Impreza 2.5RS n/a, I believe that my car has a MAP sensor and this problem does not affect me in any way? Am I correct, partially correct?

Any help is great!
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Old 10-27-2010, 03:36 PM   #1379
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Originally Posted by sr5.2 View Post
Hey everyone,
Im new to the forum and pretty new to Subaru. Apologies if this has been answered already but I don't have the time to read through 56 pages...
You're making a horrible first impression.
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Old 10-27-2010, 03:51 PM   #1380
sr5.2
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I understand this but would it be possible at all for someone to tell me if I am right?
I have done a little research behind this that's how I 'guessed' that I have the MAP, Im just looking for a confirmation from a petrol-head. That's all, thanks in advance.
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Old 10-27-2010, 04:04 PM   #1381
renyo
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You want confirmation you have a MAP sensor, or you want confirmation that you don't have to worry about problems?

99% sure you have a MAP sensor. Unless you have a sensor with a 5 wire plug next to the airbox on the passenger side of the car, you have a MAP sensor.

If you're looking for confirmation that you don't have to worry about problems, then refer to my previous post.
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Old 10-27-2010, 05:28 PM   #1382
williaty
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Quote:
Originally Posted by sr5.2 View Post
Hey everyone,
Im new to the forum and pretty new to Subaru. Apologies if this has been answered already but I don't have the time to read through 56 pages...

I own a 2002 Impreza 2.5RS n/a, I believe that my car has a MAP sensor and this problem does not affect me in any way? Am I correct, partially correct?

Any help is great!
You are MAP based and therefore this problem doesn't apply to you.







Is this Opposite Day, or what? I just posted the concise, non-snarky answer. I think hell might just have frozen over.
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Old 10-29-2010, 03:45 PM   #1383
sr5.2
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Thank you williaty! Im just not as experienced so I seek to my elders for advice

@renyo thanks too! And no, I wasn't looking for a confirmation that I won't have any problems...hehe, I bought a used car, I know how it works.

Thanks guys! Loving the forum
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Old 10-29-2010, 11:26 PM   #1384
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Oh, well sorry for being a bit of a ****. You wouldn't have been the first person to come to this thread and ask if the problem happened with the MAP sensor setup (if that was what you had actually been asking).
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Old 11-03-2010, 11:40 AM   #1385
joey horvath
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what happed to the good old days when a little trip to the plumbing department and canadian tire was all it took for a c a i
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Old 11-03-2010, 02:02 PM   #1386
Soul Shinobi
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Computerized fuel injection happened.
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Old 11-07-2010, 08:35 PM   #1387
BlueMolecule
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hey williaty would you help me build a hybrid intake. how far is deleware county from pittsburgh? trying to figure out what I would need to do this, its all scattered on this forum different model years and parts from ebay, going to search.
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Old 11-07-2010, 08:38 PM   #1388
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Yes, I'd help, but it's a damned long drive. Probably 5 hours one way.
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Old 11-07-2010, 08:56 PM   #1389
BlueMolecule
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Originally Posted by williaty View Post
Yes, I'd help, but it's a damned long drive. Probably 5 hours one way.
damn that is far, didnt look quite so distant on google maps. well maybe in the spring or something. I just remembered that i had subscribed to the 08 hybrid forum.
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Old 11-09-2010, 08:31 PM   #1390
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ive read about 10 pages of this so far and was just curious, did the maf spike occur at WOT or was the error proportional to the % of throttle
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Old 11-09-2010, 08:34 PM   #1391
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Originally Posted by nasa779 View Post
ive read about 10 pages of this so far and was just curious, did the maf spike occur at WOT or was the error proportional to the % of throttle
It's proportional to the throttle opening. At low throttle opening angles it gets small enough you don't have to care about it.
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Old 11-10-2010, 09:50 AM   #1392
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I just think iits weird that no matter the amount of airflow going through the intake, the resonance is still there and it doesn't change what rpm it the resonance occurs
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Old 11-10-2010, 10:07 AM   #1393
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Well (if I understand it correctly) the resonance is caused by the intake valves and their timing.

Changing the throttle angle should just change how much of the wave is reflected back into the engine side of the intake. The more energy that's reflected back, the less energy that propagates into the MAF side of the intake. Less energy is less amplitude.
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Old 11-10-2010, 12:45 PM   #1394
williaty
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Quote:
Originally Posted by nasa779 View Post
I just think iits weird that no matter the amount of airflow going through the intake, the resonance is still there and it doesn't change what rpm it the resonance occurs
The resonance occurs at the RPM at which the valves are opening and closing at the same frequency as the resonant frequency of the intake tract. The resonant frequency of the intake tract is determined by the wavelength of the standing wave in the intake tract. The length of the standing wave in the intake tract is determined by the length of the intake tract itself. This is why the resonance always occurs at the same RPM: the intake tract is always the same length.

The really interesting question is why don't we see smaller resonances at octave multiples of the primary? I haven't figured that one out yet.


Quote:
Originally Posted by renyo View Post
Well (if I understand it correctly) the resonance is caused by the intake valves and their timing.

Changing the throttle angle should just change how much of the wave is reflected back into the engine side of the intake. The more energy that's reflected back, the less energy that propagates into the MAF side of the intake. Less energy is less amplitude.
It's unclear if the throttle is determining the amplitude of the resonance via being an obstruction to the propagation of the wave or by controlling flow velocity.
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Old 11-27-2010, 11:33 PM   #1395
Navi271
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Hmm, pretty much decided to get rid of my weapon R intake, and use the same pipe to make a hybrid. I'm wondering if this is why I seem to go slower at WOT than I do at just under WOT?

Either way, going back to stock kinda. I seem to be doing that a lot with my car lately. I think now that I'm older and wiser I see that the things I did to the car early on are not necessarily better for it. I've grown tired of the noise the SRI would make too. Can't wait for that to go away.
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Old 11-28-2010, 12:48 AM   #1396
Soul Shinobi
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Originally Posted by Navi271 View Post
Hmm, pretty much decided to get rid of my weapon R intake, and use the same pipe to make a hybrid. I'm wondering if this is why I seem to go slower at WOT than I do at just under WOT?

Either way, going back to stock kinda. I seem to be doing that a lot with my car lately. I think now that I'm older and wiser I see that the things I did to the car early on are not necessarily better for it. I've grown tired of the noise the SRI would make too. Can't wait for that to go away.
I feel the same thing, faster just before WOT. I think it's the switchover to open loop, using preset fuel maps at WOT that are rich to protect the engine. I'd love to hear someone who knows exactly what happens explain it though.
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Old 11-29-2010, 01:20 AM   #1397
Kevin Thomas
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If you have an sri, is there any reason to believe that the air filter itself could be instigating the low end maf voltage spikes and that perhaps a different air filter will show a different result? I have a little experience with changing a Weapon R air filter on a dyno and the results were eye-opening (On a non-subaru vehicle). I just did not capture the air/fuel ratio down to that low of an rpm range (or maf voltage for that matter).

Also, couldn't an SAFC counter the running rich causing spike of an SRI so you have the best of both worlds?
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Old 11-29-2010, 01:25 AM   #1398
williaty
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No, this is being caused by the lack of a Helmholtz resonator, not the air filter.

No, an SAFC or other piggyback device can't do anything at all for this because of the way the ECU operates.
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Old 11-29-2010, 02:23 AM   #1399
Kevin Thomas
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Quote:
Originally Posted by williaty View Post
No, this is being caused by the lack of a Helmholtz resonator, not the air filter.

No, an SAFC or other piggyback device can't do anything at all for this because of the way the ECU operates.
You were very specific in your original post -->
"This report applies to any MAF-based naturally-aspirated GD/GG H4 Subaru. Most of the people who will be interested in this are going to be 05 2.5RS owners and 06-07 2.5i owners."

My apologies!

I just ordered a bluetooth OBD2 elm scantool for the android phone right after reading this whole thing. Gonna download some OBD2 apps and check some logs. The 1997 Outback is turbocharged but it is still worth a look with this as well as a couple other cars. Thanks!
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Old 11-29-2010, 02:31 AM   #1400
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I'll be interested to see if a generic scan tool (aka anything other than RomRaider) can poll the ECU fast enough to catch this.
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