Stock and only hitting 5psi......Where to look?

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GTEASER
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Stock and only hitting 5psi......Where to look?

Post by GTEASER »

Hey guys!!! First I want to say that this board is AWESOME!!!

Before I get any "do a search" comments, I have done a search, many searches, and I have been doing lots of reading, but there is a lot to process, especially with a car I am not yet familiar with. I just got my completely stock '92 SS last week and the learning curve is very steep. The car has 158k miles on it and is in pretty good condition overall and looks well taken care of throughout its life. The car runs very well, so I figured it would a good idea to get a boost gauge right away to make sure the turbo is performing properly and I am hitting stock target boost before I start with any mods such as an intercooler, the Apexi intake, or exhaust.

So I picked up a mechanical Autometer SportComp boost gauge and installed it last night. It only came with a Tee for 1/8" vac lines so I was relegated to installing it on the vac line that comes off the Cylinder 1 intake runner near the charcoal canister. I would have preferred putting it on the reference vac line going to the BPV, but that is 1/4" hose. I have ordered a 1/4" tee and it should be here by the end of the week.

At idle vac is a solid 21 in/hg and on decal in gear it drops to 25 in/hg. With moderate throttle input it quickly comes out of vac and climbs to 0 psi, but at WOT it won't seem to hit anything more than 4-5 psi of boost.

Now the interesting part, and something I was only able to verify with the boost gauge........as soon as I get into positive boost pressure, a whistling sound starts coming from under the hood. It increases a little louder with more throttle input but really stays very constant as long as I am in boost.

So it would appear that I have a boost leak somewhere after the compressor, or... the wastegate or BPV are not working properly. Any other ideas? And is there a diagram somewhere on this board so that I can be certain that I have checked all vac lines and connections? Is there a good way to test the wastegate and BPV?

Thanks in advance!!!
cj91legss
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Re: Stock and only hitting 5psi......Where to look?

Post by cj91legss »

Here's the vacuum hose reference.

http://bbs.legacycentral.org/viewtopic.php?f=1&t=15268

When our Turbo Legacys are pushing 5 psi, it usually means the car is in limp mode. Do you have a check engine light? If so I would pull the codes and start there. It does sound like you have a boost leak. With the car idling I would spray all the pcv and vacuum hoses with starter fluid to see if the idle increases. If the idle does increase, it's a good indicator of a leak.
91 L-TW Wagon with a full Swap -RIP
92 SS Prefaced, GD dash swapped, 22T/205 Hybrid 20 psi - BEAST!
93 SS Bone Stock Gone!
94 TW Bone Stock Gone!
91 SS 4EAT Sold!
98 LGT 4EAT
98 LGT Wagon 4EAT
subaru_styles
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Re: Stock and only hitting 5psi......Where to look?

Post by subaru_styles »

had the 5psi problem with my car for MONTHS with no cel light. tried new knock sensor, plugs, wires, coilpack, n didnt fix it.......

.even though there was no fault code for it, cleaned my maf. instanly back to normal
1994 SS "JDM-OEM"

1997 2.5gt wagon

1999 2.5gt wagon

1994 gt wagon
GTEASER
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Re: Stock and only hitting 5psi......Where to look?

Post by GTEASER »

Thanks guys!! No CEL. I will try the starter fluid trick and also clean the MAF and report back. I printed out the vac diagram as well as the PCV diagram.
cj91legss
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Re: Stock and only hitting 5psi......Where to look?

Post by cj91legss »

Use MAF cleaner on the MAF. It doesn't leave a residue like brake parts cleaner would.
91 L-TW Wagon with a full Swap -RIP
92 SS Prefaced, GD dash swapped, 22T/205 Hybrid 20 psi - BEAST!
93 SS Bone Stock Gone!
94 TW Bone Stock Gone!
91 SS 4EAT Sold!
98 LGT 4EAT
98 LGT Wagon 4EAT
GTEASER
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Location: SF Bay Area, CA

Re: Stock and only hitting 5psi......Where to look?

Post by GTEASER »

cj91legss wrote:Use MAF cleaner on the MAF. It doesn't leave a residue like brake parts cleaner would.
Yep, thank you, gonna pick some up after my meeting tonight. I will clean the MAF and reset the ECU and see what happens on the way to work in the morning.
Legacy777
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Re: Stock and only hitting 5psi......Where to look?

Post by Legacy777 »

The other thing to mention is that in partial boost you can sometimes hear the turbo noise which kind of sounds like a fluttering. Does the noise you hear sound like a whistle or something slightly different?
Josh

surrealmirage.com/subaru
1990 Legacy (AWD, 6MT, & EJ22T Swap)
2020 Outback Limted XT

If you need to get a hold of me please email me rather then pm
GTEASER
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Re: Stock and only hitting 5psi......Where to look?

Post by GTEASER »

A whistle. I will be getting to this later today. Will update.
GTEASER
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Re: Stock and only hitting 5psi......Where to look?

Post by GTEASER »

That was it guys! Thanks so much subaru_styles! The MAF was visibly dirty and it took a lot of squirts of the MAF cleaner to get the black gunk off of it. Shiny clean wires now. I disconnected the battery to reset the ECU so it can relearn. I'm hitting 8 psi now and the car pulls much harder in the lower rpm's, and runs noticeably smoother all around.
Legacy777
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Re: Stock and only hitting 5psi......Where to look?

Post by Legacy777 »

Glad to hear you got it fixed.
Josh

surrealmirage.com/subaru
1990 Legacy (AWD, 6MT, & EJ22T Swap)
2020 Outback Limted XT

If you need to get a hold of me please email me rather then pm
subaru_styles
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Re: Stock and only hitting 5psi......Where to look?

Post by subaru_styles »

GTEASER wrote:That was it guys! Thanks so much subaru_styles! The MAF was visibly dirty and it took a lot of squirts of the MAF cleaner to get the black gunk off of it. Shiny clean wires now. I disconnected the battery to reset the ECU so it can relearn. I'm hitting 8 psi now and the car pulls much harder in the lower rpm's, and runs noticeably smoother all around. Image
8)
1994 SS "JDM-OEM"

1997 2.5gt wagon

1999 2.5gt wagon

1994 gt wagon
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