Twin Turbo Boost + Misc
09 January 2003, 08:47 PM
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Hi Jeff
Not sure about the boosting problem on the secondary turbo - mine is quite stable. Considered a boost guage? There is definitely a rush at about 4.5-5K, and then settles, but not the surging you describe.
The wires are indeed for heated seats, but if they're not plugged into anything then they're there already for the heated seat option - if they're plugged in I think you'll find they're for the setbelt warning light.
The rocker head gasket (common problem!) is the same as an Impreza.
Not sure about the boosting problem on the secondary turbo - mine is quite stable. Considered a boost guage? There is definitely a rush at about 4.5-5K, and then settles, but not the surging you describe.
The wires are indeed for heated seats, but if they're not plugged into anything then they're there already for the heated seat option - if they're plugged in I think you'll find they're for the setbelt warning light.
The rocker head gasket (common problem!) is the same as an Impreza.
10 January 2003, 11:35 AM
#4
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Being new to legacy's, unfortunatley cant give you any advice regarding boost pulses.
std boost however is 0.5 primary and 0.9 secondary.
Ecu is self learning.
What fuel are you running?
Just give some time on the b4 site, most of the people with knowledge, are on the other side of the planet.
'bansheemax' legacyb4
Mark
std boost however is 0.5 primary and 0.9 secondary.
Ecu is self learning.
What fuel are you running?
Just give some time on the b4 site, most of the people with knowledge, are on the other side of the planet.
'bansheemax' legacyb4
Mark
10 January 2003, 03:11 PM
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Jeff,
"If my boost pressure is oscillating up and down, what is the likely cause and how can I fix it?"
The twin-turbo setup is too complex to guess about. Fit a boost gauge - its not difficult or expensive - and see for sure whats happening. I havn't spent time/money on a pukka installation (yet).
The restrictor affects the dynamics of the boost control it doesnt affect the quantity of boost (unless you make it so big or small that you disable boost control). Thats controlled by bleeding pressure from the wastegate vacuum line by the ecu-controlled boost solenoid. Some people replace the boost solenoid with a mechanical bleed valve such as the Dawes device. Fitting one will remove over-boost oscillation (if thats what you have) BUT it also removes the overboost protection that the ecu provides (and in my case is what is giving oscillation). Also the ecu can control boost levels for when the primary only is running & then for prim&secondary together, and you cant do that with a Dawes.
I'll let you know how I get on with the adjustable restrictor but my car is going to be off the road for a few weeks yet.
The ecu can be reset but an overnight battery disconnect.
I'm afraid we're all groping in the dark with these cars, there are no experts on them outside Subaru and they're not going to help you!
"If my boost pressure is oscillating up and down, what is the likely cause and how can I fix it?"
The twin-turbo setup is too complex to guess about. Fit a boost gauge - its not difficult or expensive - and see for sure whats happening. I havn't spent time/money on a pukka installation (yet).
The restrictor affects the dynamics of the boost control it doesnt affect the quantity of boost (unless you make it so big or small that you disable boost control). Thats controlled by bleeding pressure from the wastegate vacuum line by the ecu-controlled boost solenoid. Some people replace the boost solenoid with a mechanical bleed valve such as the Dawes device. Fitting one will remove over-boost oscillation (if thats what you have) BUT it also removes the overboost protection that the ecu provides (and in my case is what is giving oscillation). Also the ecu can control boost levels for when the primary only is running & then for prim&secondary together, and you cant do that with a Dawes.
I'll let you know how I get on with the adjustable restrictor but my car is going to be off the road for a few weeks yet.
The ecu can be reset but an overnight battery disconnect.
I'm afraid we're all groping in the dark with these cars, there are no experts on them outside Subaru and they're not going to help you!
11 January 2003, 10:11 AM
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Blimey Jeffrey, how'd you get to Sept of 2003 already 
Anyway, the start point could also be to make sure the vacuum pipes are all intact and in good condition. Make sure that none are loose - I had one that would blow off just enough to let some
air in/out on the road and then at idle would cheekily slip back into place at idle. I ended up clamping all the buggers down!
TT's advice on the B4 group is sound too.
HTH
Anyway, the start point could also be to make sure the vacuum pipes are all intact and in good condition. Make sure that none are loose - I had one that would blow off just enough to let some
air in/out on the road and then at idle would cheekily slip back into place at idle. I ended up clamping all the buggers down!
TT's advice on the B4 group is sound too.
HTH
11 January 2003, 10:15 AM
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Ooh, one other thing - what oil are you using?
We have had one case of 15w weight Motul oil causing some interesting boost, too (and after speaking to some other owners on the Japanese list, there seemed to have been a couple of such cases). It seems that the TTs prefer 10w at most, and in winter I run 5w, in fact all the Japan based guys are running 5w-40 at the mo' AFAIK.
Cheers,
Anton
We have had one case of 15w weight Motul oil causing some interesting boost, too (and after speaking to some other owners on the Japanese list, there seemed to have been a couple of such cases). It seems that the TTs prefer 10w at most, and in winter I run 5w, in fact all the Japan based guys are running 5w-40 at the mo' AFAIK.
Cheers,
Anton
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12 January 2003, 05:06 PM
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Only one I've seen listed for Scoobs here is 100% synth.
Just remember that I said "seems" coz I have not used the Motul stuff myself, nor have I experienced the boost issues (I always use 5w-40 in winter, and will use 10w-50 in summer on occaision).
Just remember that I said "seems" coz I have not used the Motul stuff myself, nor have I experienced the boost issues (I always use 5w-40 in winter, and will use 10w-50 in summer on occaision).
01 September 2003, 05:31 PM
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I have recently purchased a 95 Legacy GT Twin Turbo Manual Estate.
I have been experiencing fluctuating boost pressure (on the secondary turbo) and am trying to find out why this is happening and hopefully how to fix the problem. Am using Optimax fuel.
I have read several threads on restrictors, sizes etc. and how they affect the overboost - does the size of the restrictor also affect the steady state boost pressure or does it simply affect the overboost?
I assume (but am not certain) that Subaru intended it's turbo engined cars to have a second or so of higher boost before dropping back to a lower steady state boost pressure, is this correct?
If my boost pressure is oscillating up and down, what is the likely cause and how can I fix it?
What is the standard boost on the primary and secondary turbo's and can these be increased by simply changing the restrictor(s)?
I have seen people saying you must do an ECU reset after certain mods, does this mean the ECU has some sort of 'adaptive learning' if so what does it 'learn' and why does a reset help? Can a reset be achieved by simply disconnecting the battery for a while?
What are the wires under the front seats for? Are they heated, if so how do I turn them on?
I have a leaky cam cover gasket which needs replacing, what sort can I buy from Subaru to fit?
Sorry for the 100's of questions but I am new to the Subaru world and need to get up to speed on all the nitty gritty, any help would be gratefully received.
Many thanks.
Jeffrey
[Edited by Telephonewire - 1/10/2003 12:02:16 PM]
I have been experiencing fluctuating boost pressure (on the secondary turbo) and am trying to find out why this is happening and hopefully how to fix the problem. Am using Optimax fuel.
I have read several threads on restrictors, sizes etc. and how they affect the overboost - does the size of the restrictor also affect the steady state boost pressure or does it simply affect the overboost?
I assume (but am not certain) that Subaru intended it's turbo engined cars to have a second or so of higher boost before dropping back to a lower steady state boost pressure, is this correct?
If my boost pressure is oscillating up and down, what is the likely cause and how can I fix it?
What is the standard boost on the primary and secondary turbo's and can these be increased by simply changing the restrictor(s)?
I have seen people saying you must do an ECU reset after certain mods, does this mean the ECU has some sort of 'adaptive learning' if so what does it 'learn' and why does a reset help? Can a reset be achieved by simply disconnecting the battery for a while?
What are the wires under the front seats for? Are they heated, if so how do I turn them on?
I have a leaky cam cover gasket which needs replacing, what sort can I buy from Subaru to fit?
Sorry for the 100's of questions but I am new to the Subaru world and need to get up to speed on all the nitty gritty, any help would be gratefully received.
Many thanks.
Jeffrey
[Edited by Telephonewire - 1/10/2003 12:02:16 PM]
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