No boost on secondary

[Rosssub]

That\'s the Secondary Relief Valve. Yeah should be VF18/19.

The VF27 has no Waste Gate but the VF19 does, afaik. Someone will clarify.

So you could run into Secondary Waste Gate/ECU/Differential Sensor trouble/CEL 65/66? I assume when Subaru deleted the Secondary Waste Gate they increased the use of the ECV and Primary Duty Solenoid to compensate.

Maybe ignore my VF27 comment and stick with looking for a VF19 ;D with no or very minimal shaft play and no visible fin damage front and back.

This should be ok with only 100000ish kms:

http://www.trademe.co.nz/motors/car-parts-accessories/subaru/engines/auction-701092543.htm

[Marky]

Secondary wastegate was not operational 99% of the time

Don\'t stress about it

[TerryM]

Thanks guys. Will find a replacement and let you know how I get on once its fitted. Cheers!

[telemekas]

"The VF27 has no Waste Gate but the VF19 does, afaik. Someone will clarify."

Secondary turbo waste gates only on the series I VF14 and VF17 turbos.

[Rosssub]

 telemekas said:

"The VF27 has no Waste Gate but the VF19 does, afaik. Someone will clarify."

Secondary turbo waste gates only on the series I VF14 and VF17 turbos.

Thanks Telemekas.

So Marc\'s VF27 will be a perfect/direct fit and also a good upgrade over the OEM VF19.

[TerryM]

Thanks Rosssub. Bugger as I already bought the VF19 with 108000km off trademe.

[TerryM]

Spent the morning pulling the secondary turbo out to discover it\'s in better condition than the replacement one I bought. No evidence of oil, compressor wheel clean, no damage, no shaft play. As it looked in better condition I put it back on.

Now I\'m a bit stumped as all signs were pointing to dead turbo but I don\'t believe it\'s the case.

I blocked the secondary relief valve and went for another drive to double check it wasn\'t leaking but still not getting full boost on secondary.

Now thinking it may have something to do with exhaust? I wouldn\'t think there would be a blockage before the turbo, then after the turbo there isn\'t a cat until after the y join, so if the cat was blocked I would assume it would affect primary being able to make boost too?

Any further ideas on what to check next? I\'m a bit lost now...

[GorGasmSpecB]

Try removing the wastegate lines and see if it will free boost. SRS option.

Will tell you if it\'s turbo system or boost control/electronics related.

[Rosssub]

 GorGasmSpecB said:

Try removing the wastegate lines and see if it will free boost. SRS option.

Will tell you if it\'s turbo system or boost control/electronics related.

Carefully, be ready to button off.

[B4_685]

Just a dumb question - what fuel are you running?

B4_685 via Tapatalk HD

[TerryM]

Thanks guys. By waste gate lines do you mean the vacuum lines to the secondary exhaust control valve diaphragm thing? There is a secondary relief valve but don\'t believe there is a secondary waste gate on my model (vf19).

I have already forced it into twin turbo mode and it only made 3psi.

Been running BP 98 for the last 10 years.

Could it be a blocked exhaust causing the issue?

[Rosssub]

Primary Waste Gate, both Turbo\'s share it. Could be an Exhaust Restriction, but this should rule that out.

Disconnect and block (or just disconnect), hose 23 at the Primary Waste Gate Actuator.

This will stop your Waste Gate from opening at all. So the Turbo should make Max Possible Boost and go crazy. It could go over 20psi so be ready to back off instantly.

[GorGasmSpecB]

Hrm, might be indicative of a problem with mine, I never got over 15 on primary or ~18 on secondary at redline with the wastegate disconnected heh.

[Rosssub]

If it doesn\'t Free Boost (mine is over 20psi by 2000rpm) with Waste Gate disconnected.

Either a massive Boost Leak, or sad Turbo.

Waste Gate not seating/sealing. Broken Waste Gate Spring (flapping). Waste Gate seized open.

Blocked or Restrictive Exhaust. Cats or Muffler. (In neutral at 3000rpm Vac will drop away, or lesson with steady throttle. Rather than flicker and hold steady.)

Blocked/Restrictive Intake, collapsed Inlet Pipe? Rag? Really bad Filter?

[TerryM]

Will try that out when I\'m back home.

If the waste gate is seized open or not closing properly etc wouldn\'t that be causing boost problems on primary as well and not just secondary? Cheers

[Rosssub]

 TerryM said:

Will try that out when I\'m back home.

If the waste gate is seized open or not closing properly etc wouldn\'t that be causing boost problems on primary as well and not just secondary? Cheers

Yip. OEM Boost should be around 11psi Primary and 15psi Twin.

[TerryM]

Thanks Rosssub, so that may explain why I\'m getting 7-8psi on primary and not 11. But then if the waste gate could hold 8psi I would expect there to be 8psi when in twin mode too...

[Rosssub]

 TerryM said:

Thanks Rosssub, so that may explain why I\'m getting 7-8psi on primary and not 11. But then if the waste gate could hold 8psi I would expect there to be 8psi when in twin mode too...

During Twin the Secondary is open. Changing Exhaust Flow/Waste Gate Usage etc.

[TerryM]

Hi Rosssub thanks for the reply but I don\'t quite follow. In twin mode the IACV under the intercooler opens, and the exhaust control valve under the secondary turbo opens. There is no wastegate on the secondary turbo.

So you are saying it is possible for the primary side wastegate could be causing boost issues when in twin mode?

Also if I disconnect hose 23 isn\'t that just checking the primary turbo can make boost? The secondary exhaust control valve won\'t be open at 2000rpm so the secondary wouldn\'t be spinning...

[Rosssub]

Yes, the Primary Waste Gate/Primary Duty Solenoid controls Engine Boost Levels, during Single and during Twin.

Yes, disconnecting Hose 23 (Free Boosting) will test Primary Turbo Operation/Waste Gate/Cat Convertor/Exhaust Restrictions etc.

It would blow to pieces before you got to Twin ;D

[TerryM]

Ah ok that makes sense. I\'ll let you know how I get on. Thanks for all the help so far! I\'d be lost without this forum.

[TerryM]

Disconnected hose 23 from primary wastegate actuator then went for a drive. Boost gauge reacted same as if hose 23 was connected. Was getting about 9psi on primary at roughly 4000rpm.

Next took off rear muffler (section from diff backwards) and swapped for one that is bloody loud as all the baffling has been blown out so just a straight pipe really.

With loud muffler on and hose 23 reconnected car boosted about 10psi primary and 10-12ish secondary.

So after all the fluffing around it appears the issue is exhaust related.

Could the rear muffler be partially blocked? How can you check without cutting it in half?

Or could the mid section of the exhaust or cat etc be blocked and the free flow from hollow rear muffler overcome a partially blocked mid section? Can you check?

[Rosssub]

Have you got a Cat in the Mid Section? Or just in the Primary Down Pipe?

So just changing Rear Muffler you\'ve gone from 9psi Primary/4psi Twin, to 10psi Primary/12psi Twin?

[TerryM]

Yes I think there is a cat in the mid section. If it\'s not a cat then it is some sort of muffler? Flat square ish shape?

[TerryM]

Yes only changed rear muffler to one that doesn\'t do much muffling. Yes to those boost numbers above. Interesting how much difference there is with that small change.