Lack of boost and backfire

[Stanza.001]

Hey all, I recently bought a 99" legacy b4. It backfires/pops every now and again and even sometimes when I change up gears?. But my main reason for turning to forums is the lack of boost. Both turbos are only hitting 5psi, 6 if im lucky. This is my 1st twin turbo, and its confused the S*** out of me lol. Does anybody know what the problem could be?. Any help is appreciated, thanks in advance.

 

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[Kiwi_Fozze]

There should be a stored or constant check engine light. Get those codes read and go from there. Boost that low is normally either a big leak or ecu initiated "limp" mode

[Stanza.001]

There should be a stored or constant check engine light. Get those codes read and go from there. Boost that low is normally either a big leak or ecu initiated "limp" mode

Cheers man thank u, will have a look after work today. I cant hear any boost leak at all so it must be chilling in limp mode.

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[Kiwi_Fozze]

If it's a 2001 legacy (I'm taking a stab based on your username) you'll need a code reader to pull em, the black plugs under the dash trick doesn't work for the revision d's

[Andy_Mac]

14 minutes ago, Kiwi_Fozze said:

If it's a 2001 legacy (I'm taking a stab based on your username) you'll need a code reader to pull em, the black plugs under the dash trick doesn't work for the revision d's

 

User pic would indicate it isn’t a rev D though. Look at the front bumper and headlights plus the bit where they say it’s a 99 is a dead giveaway it aint an 01 

[Kiwi_Fozze]

9 hours ago, Andy_Mac said:

 

User pic would indicate it isn’t a rev D though. Look at the front bumper and headlights plus the bit where they say it’s a 99 is a dead giveaway it aint an 01 

Nightshifts do funny things to people's brains, herpaderp

[Stanza.001]

Just tried the 2 black cables, check light just kept flashing, continuously at the same pace?. No lights come on while I drive around normally, just low boost.

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[Stanza.001]

There should be a stored or constant check engine light. Get those codes read and go from there. Boost that low is normally either a big leak or ecu initiated "limp" mode

If it is in limp mode, how do I get it out?.


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[Decap]

Get it out of limp mode by resetting the ECU. I've got a Tactrix cable and a laptop personally and I use that with Romraider Logger to reset my ECU. FreeSSM with most cheap ODB2 cables should work too.

Other than this you may be able to do it by disconnecting your battery, but not 100% sure on this. There should also be a manual reset you can google.

 

I also recently spent $200 tracking down a boost leak I COULDN'T find after stripping the whole intake up the intake manifold out! In the end I gave up and took it to Pitstop for a smoke test and they found the leak under the dash. Still kicking myself for not trying to cut the Boost Gauge out of the loop!!! It never occurred to me that a tiny little hose split could leak so much boost!

 

I was only boosting 4PSI and the car stalled in the middle of the f'n motorway! After this was all fixed up I'm back to 15psi.

[Stanza.001]

Get it out of limp mode by resetting the ECU. I've got a Tactrix cable and a laptop personally and I use that with Romraider Logger to reset my ECU. FreeSSM with most cheap ODB2 cables should work too.
Other than this you may be able to do it by disconnecting your battery, but not 100% sure on this. There should also be a manual reset you can google.
 
I also recently spent $200 tracking down a boost leak I COULDN'T find after stripping the whole intake up the intake manifold out! In the end I gave up and took it to Pitstop for a smoke test and they found the leak under the dash. Still kicking myself for not trying to cut the Boost Gauge out of the loop!!! It never occurred to me that a tiny little hose split could leak so much boost!
 
I was only boosting 4PSI and the car stalled in the middle of the f'n motorway! After this was all fixed up I'm back to 15psi.

Cheers man, I might have a look tomorrow. Ive had a really bad feeling about my boost gauge, so I might check the hose in the dash. No obvious air leak though, and ive done the battery reset also, still no luck. Looking forward to that 15psi though lol, 5psi just isnt cutting it

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[Decap]

1 hour ago, Stanza.001 said:

Cheers man, I might have a look tomorrow. Ive had a really bad feeling about my boost gauge, so I might check the hose in the dash. No obvious air leak though, and ive done the battery reset also, still no luck. Looking forward to that 15psi though lol, 5psi just isnt cutting it

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Easiest thing to do would be to use a short piece of vac hose with a plug on the side of the T-connector in the engine bay that normally has your boost gauge vac hose. This would be easier than working under the dash for testing.

 

Edited November 28, 2017 by Decap