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space
Samba Member
Joined: November 19, 2017
Posts: 673
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 Posted: Wed Jun 07, 2023 5:43 am Post subject: designing a fresh air intake subie 2.5 |
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In another thread I experienced problems with lagging/bucking while traveling out west
The suggestions were fuel pump and filter replacements
My trouble codes were p0171 and p0457 (lean bank 1 and loose or missing gas cap, respectively)
I didnt have my code reader at the time ("Dash Command" gave me the generic readings)
When I arrived home I used my actual diagnostic tool
and saw my long term trim was very high, as was the shrt term (+25 combined)
after removing the air filter it dropped to 0 LT and +- 5ish ST
After installing a new air filter ST went to +15, which seems high (LT still 0 for now)
I have an 87 jag xl6 filter/housing
So my questions are:
1 would it be prudent to enlarge the intake side of the housing (currently 1-1.5 inches) to allow more air flow?
2 the oem subie setup has what appears to be a catch basin style intake which I assume is to collect heavier particulate, Is it necessary?
3 my thoughts are to extend the housing intake up the pillar, add a pre filter/rain sock and a catch basin style "P trap" to collect the heavier particulate or install an inline pre filter such as this https://www.westatesystems.com/products/turbo-flexnline/
4 Am I Rube Goldberging the solution?
Any thoughts?
fwiw Ive searched the site and came up with many of these ideas, but no one is using an 87 jag set up
T
_________________
82 westy
w:
2.5 JDM Subie
Rear discs
Last edited by space on Wed Jun 07, 2023 6:09 am; edited 2 times in total |
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dobryan
Samba Member
Joined: March 24, 2006
Posts: 16505
Location: Brookeville, MD
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| Posted: Wed Jun 07, 2023 5:58 am Post subject: Re: designing an fresh air intake subie 2.5 |
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| space wrote: |
So my questions are:
1 would it be prudent to enlarge the intake side of the housing (currently 1-1.5 inches) to allow more air flow? |
Are you saying that you are feeding the entire intake thru a 1-1.5" opening?
If so, that seems way too small. I use the stock subie airbox and the tubes are the same size as the throttle body opening.
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Dave O
'87 Westy w/ 2002 Subaru EJ25 and Peloquin TBD
"To travel hopefully is a better thing than to arrive." Robert Louis Stevenson
MD>Canada>AK>WA>OR>CA>AZ>UT>WY>SD
https://www.thesamba.com/vw/forum/viewtopic.php?t=620646
Building a bus for travel in Europe (euroBus)
https://www.thesamba.com/vw/forum/viewtopic.php?t=695371
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https://www.thesamba.com/vw/forum/viewtopic.php?t=746794 |
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space
Samba Member
Joined: November 19, 2017
Posts: 673
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| Posted: Wed Jun 07, 2023 6:03 am Post subject: Re: designing an fresh air intake subie 2.5 |
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| dobryan wrote: |
| space wrote: |
So my questions are:
1 would it be prudent to enlarge the intake side of the housing (currently 1-1.5 inches) to allow more air flow? |
Are you saying that you are feeding the entire intake thru a 1-1.5" opening?
If so, that seems way too small. I use the stock subie airbox and the tubes are the same size as the throttle body opening. |
The "funnel" fresh air side opening is approx 1.5" flaring to approx 3" at the can
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Franklinstower
Samba Member
Joined: September 21, 2006
Posts: 1896
Location: PNW
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| Posted: Wed Jun 07, 2023 7:07 am Post subject: Re: designing a fresh air intake subie 2.5 |
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The jag air filter was designed for 4.2 ltrs. I would doubt that is the issue. If your lean in bank 1, more air isn't going to help. I would look at your maf and your fuel pressure before messing with a new filter box. Or am I missing something?
Maybe smoke your intake for leaks.
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'89 Westy - EJ25/22 Frank 4.44 5mt
'75 Miami Blue Sunroof FI Standard Bug |
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space
Samba Member
Joined: November 19, 2017
Posts: 673
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| Posted: Wed Jun 07, 2023 8:42 am Post subject: Re: designing a fresh air intake subie 2.5 |
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| Franklinstower wrote: |
The jag air filter was designed for 4.2 ltrs. I would doubt that is the issue. If your lean in bank 1, more air isn't going to help. I would look at your maf and your fuel pressure before messing with a new filter box. Or am I missing something?
Maybe smoke your intake for leaks. |
More air did help bring the fuel trims into spec (Testing w/o the filter)
Once the new filter was installed the stft went to +15 which should eventually have an effect on the ltft
MAF is at spec, havent checked fuel pressure yet
T
Edit: I do have a spare MAF sensor I can test whether the readings are consistent
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82 westy
w:
2.5 JDM Subie
Rear discs
Last edited by space on Wed Jun 07, 2023 8:55 am; edited 1 time in total |
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dobryan
Samba Member
Joined: March 24, 2006
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Location: Brookeville, MD
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| Posted: Wed Jun 07, 2023 8:45 am Post subject: Re: designing a fresh air intake subie 2.5 |
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| space wrote: |
| Franklinstower wrote: |
The jag air filter was designed for 4.2 ltrs. I would doubt that is the issue. If your lean in bank 1, more air isn't going to help. I would look at your maf and your fuel pressure before messing with a new filter box. Or am I missing something?
Maybe smoke your intake for leaks. |
More air did help bring the fuel trims into spec (Testing w/o the filter)
Once the new filter was installed the stft went to +15 which should eventually have an effect on the ltft
MAF is at spec, havent checked fuel pressure yet
T |
Can you remove that intake funnel to see what difference it may make?
(I know it is designed for the 4.2l Jag but my head hurts thinking about feeding an engine with a 1.5" opening.)
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Dave O
'87 Westy w/ 2002 Subaru EJ25 and Peloquin TBD
"To travel hopefully is a better thing than to arrive." Robert Louis Stevenson
MD>Canada>AK>WA>OR>CA>AZ>UT>WY>SD
https://www.thesamba.com/vw/forum/viewtopic.php?t=620646
Building a bus for travel in Europe (euroBus)
https://www.thesamba.com/vw/forum/viewtopic.php?t=695371
The Western Syncro build
https://www.thesamba.com/vw/forum/viewtopic.php?t=746794 |
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Crankey
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space
Samba Member
Joined: November 19, 2017
Posts: 673
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| Posted: Wed Jun 07, 2023 8:56 am Post subject: Re: designing a fresh air intake subie 2.5 |
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| dobryan wrote: |
| space wrote: |
| Franklinstower wrote: |
The jag air filter was designed for 4.2 ltrs. I would doubt that is the issue. If your lean in bank 1, more air isn't going to help. I would look at your maf and your fuel pressure before messing with a new filter box. Or am I missing something?
Maybe smoke your intake for leaks. |
More air did help bring the fuel trims into spec (Testing w/o the filter)
Once the new filter was installed the stft went to +15 which should eventually have an effect on the ltft
MAF is at spec, havent checked fuel pressure yet
T |
Can you remove that intake funnel to see what difference it may make?
(I know it is designed for the 4.2l Jag but my head hurts thinking about feeding an engine with a 1.5" opening.) |
Was thinking the same!
I will check it out when Im back home
btw how did u get the oem subie air filter to work?
There doesnt seem to be enough room in the engine bay
T
_________________
82 westy
w:
2.5 JDM Subie
Rear discs
Last edited by space on Wed Jun 07, 2023 8:59 am; edited 2 times in total |
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space
Samba Member
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| Posted: Wed Jun 07, 2023 8:58 am Post subject: Re: designing a fresh air intake subie 2.5 |
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Saw that in my search
Definitely a fall back solution
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11BC2
Samba Member
Joined: August 27, 2017
Posts: 495
Location: Cool, California
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| Posted: Wed Jun 07, 2023 9:02 am Post subject: Re: designing a fresh air intake subie 2.5 |
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| What year is the engine & ECM? |
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space
Samba Member
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| Posted: Wed Jun 07, 2023 9:05 am Post subject: Re: designing a fresh air intake subie 2.5 |
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| 11BC2 wrote: |
| What year is the engine & ECM? |
2005
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Franklinstower
Samba Member
Joined: September 21, 2006
Posts: 1896
Location: PNW
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| Posted: Wed Jun 07, 2023 9:22 am Post subject: Re: designing a fresh air intake subie 2.5 |
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| space wrote: |
| 11BC2 wrote: |
| What year is the engine & ECM? |
2005 |
Okay, I have an '05 outback (my sons) and it was having consistently poor idle and stumble. I can't remember the codes I pulled, but it was a lean condition. I thought MAF, so I changed it. That worked for a couple of months. But it came back, tried a different MAF (these were all Pick-n-Pull MAF's) that worked for a while. I was about to go through the fuel pressure check, when I cleaned and installed a third MAF sensor. I have now been trouble free for 2 years with the last MAF installed.
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'89 Westy - EJ25/22 Frank 4.44 5mt
'75 Miami Blue Sunroof FI Standard Bug
Last edited by Franklinstower on Wed Jun 07, 2023 11:23 am; edited 1 time in total |
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skills@eurocarsplus
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Joined: January 01, 2007
Posts: 16879
Location: sticksville, ct.
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| Posted: Wed Jun 07, 2023 9:29 am Post subject: Re: designing a fresh air intake subie 2.5 |
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| space wrote: |
2 the oem subie setup has what appears to be a catch basin style intake which I assume is to collect heavier particulate, Is it necessary?
T |
what you're seeing is called a helmholtz resonator.
it helps more with MAF based cars, MAP based cars don't seem to care as much but a properly sized intake should help out
either way, your STFT should be around +10 to -10 so you're not very far off.
the LTFT should average about the same. obviously, the closer it is to zero the better you are...
from your description, it sounds to me like you may have too small of a fresh air intake on your swap
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Sodo
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Joined: July 06, 2007
Posts: 9615
Location: Western WA
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| Posted: Wed Jun 07, 2023 9:45 am Post subject: Re: designing a fresh air intake subie 2.5 |
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| Franklinstower wrote: |
| The jag air filter was designed for 4.2 ltrs. I would doubt that is the issue. |
Agreed. If you need much air as a 4.2L engine, you would need that much fuel too.
Your gearbox will appreciate any "limitations" to full-power (that it can get).
But a limit on your throttle-plate full-opening is better than a limit on the airbox intake.
An SVX friend has limited the throttle plate to 60% and he says the gearbox still still doesn't last very long.
I think a lot of EJ25s have oil consumption problems because dust gets past the filter and wears out the piston rings.
Even on Subaru OEM airboxes.
Hows the "white glove test" in your intake, on the clean side of the filter?
An air pre-cleaner is a beautiful thing for dusty roads, but kinda bulky otherwise.
It's fairly easy to plumb up to the high "VW air intake" to get clean air for most cases even on dusty roads.
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space
Samba Member
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| Posted: Wed Jun 07, 2023 10:45 am Post subject: Re: designing a fresh air intake subie 2.5 |
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Thanks for all the input and ideas
Gives me direction to proceed
As far as "white glove test" it was imo, pretty dusty on the clean side of the filter housing
thanks again everyone
I will report back
T
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Rear discs |
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valvecovergasket
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Joined: October 10, 2018
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| Posted: Wed Jun 07, 2023 10:52 am Post subject: Re: designing a fresh air intake subie 2.5 |
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| Sodo wrote: |
It's fairly easy to plumb up to the high "VW air intake" to get clean air for most cases even on dusty roads. |
i will add here that i recently redid the air plumbing on my tdi swap - which i built originally to use only the rmw subaru box pulling from the bottom of the drivers side pillar.
a few thousand miles of around town driving and camping on not-overly-extreme dusty roads the filter that the airbox shipped with was absolutely done for.
it was incredibly dusty pulling only from the lower portion of the pillar
none of that was making it past the filter, but the filter was shockingly full.
so definitely consider getting fresh air from higher up somewhere.
ive now plumbed in the spectre universal kit up to the factory snorkel (which you can still buy new...) high up in the pillar.
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space
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| Posted: Wed Jun 07, 2023 10:59 am Post subject: Re: designing a fresh air intake subie 2.5 |
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[quote="valvecovergasket"]
| Sodo wrote: |
It's fairly easy to plumb up to the high "VW air intake" to get clean air for m
ive now plumbed in the spectre universal kit up to the factory snorkel (which you can still buy new...) high up in the pillar. |
You wouldnt happen to have a spectre part number for the universal kit?
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valvecovergasket
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| Posted: Wed Jun 07, 2023 11:07 am Post subject: Re: designing a fresh air intake subie 2.5 |
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looks like i got both on amazon
Spectre 8741 for the hose and adapters
Spectre 8148 for the flange
here it is mounted to the RMW box
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11BC2
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| Posted: Wed Jun 07, 2023 12:33 pm Post subject: Re: designing a fresh air intake subie 2.5 |
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OK.
The MAF has to be in the same size tube/hose/ducting as the OEM Subaru ducting.
If it is, have you checked smoke tested the intake for leaks?
If no leaks, and fuel pressure is good(can't remember the last time I changed a Subaru FPR), I'd suggest a new DENSO MAF and AFR.
Post pictures of your setup. |
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space
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| Posted: Wed Jun 07, 2023 1:47 pm Post subject: Re: designing a fresh air intake subie 2.5 |
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| 11BC2 wrote: |
OK.
The MAF has to be in the same size tube/hose/ducting as the OEM Subaru ducting.
If it is, have you checked smoke tested the intake for leaks?
If no leaks, and fuel pressure is good(can't remember the last time I changed a Subaru FPR), I'd suggest a new DENSO MAF and AFR.
Post pictures of your setup. |
I did a smoke test (prelim, not with a smoke machine)
Im thinking the gas cap may be letting unmetered air in
Cap is on order
Checked trims w "funnel" off, seems to have stabilized the readings (+15 to +16 combined)
I do think it maybe prudent to run a full size intake hose/pipe in the pillar
Ive had the existing setup for 20k miles and it never let me down
That being said I hadnt taken trim readings on the motor before
The filter was pretty dirty when the issues were occurring
Being an odd filter its not easily obtainable by a quick trip to the parts store
T
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