Question about Subaru Legacy

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I have no turbo boost from my 2.0 GT twin stage turbo

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  • dmskeine Jul 25, 2008

    1997 subaru legacy ej20 gt twin turbo with no turbo boost

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If your boost is gone, your best first bet is to look at vacuum lines in the engine bay - make sure none of them are cracked or dry-rotted. A vacuum leak will cause your boost pressure to vent to the atmosphere.

The car has a valve called a diverter valve or recirculation valve on it as well. Usually the OEM valves have plastic diaphragms that can fail and will cause your boost to bleed off. This valve will be piped into one of the inlet pipes between your intercooler and throttle body via a vacuum line - trace your vacuum lines back and you should be able to find it. An owner's forum for your car will probably have photos to show you its location. If that has failed (which can happen if your mileage is somewhat high, or if you have a boost controller to raise the boost), you'll have no boost.

Vacuum leaks of some sort or other are the typical culprit in lost boost pressure about 99% of the time - most of the time you can find them just by inspecting the vacuum lines. If you find one that's disconnected, reconnect it, and if one is cracked or broken, replace it, and your problem should be solved.

Posted on Jul 25, 2008

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  • Subaru Master
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You need to check power to low pressure switch, that is on the accumulator.
If there is no power in there, then the problem is between the switch and control panel.It is possible the compressor clutch s bad.if there is power to the compressor and still does not run then compressor clutch is bad.

Posted on Jul 24, 2008

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SOURCE: no boost

Check all the rubber hoses to and from the inner cooler for cracks, make sure all the clamps are tight.

Posted on Aug 07, 2008

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1 Answer

Turbo not boosting opel corsa 1.7dti club bakkie


In the old days the turbo would boost as soon as the engine speed was sufficiently high and any over pressure would be dumped by a relief valve or controlled by a wastegate.



In these modern times of electronics the turbo wastegate is normally open instead of normally closed so there is no automatic boost. The engine management system decides when there will be boost and how much boost there will be.



Turbo chargers are amazingly reliable unless they are abused or there has been foreign matter ingress. When looking for the cause of no boost it is wise to disconnect the intake trunking and turn the compressor vanes by hand to ensure all is well.



Disconnect the vacuum line to the wastegate servo and apply suction to the servo to ensure the servo, the linkage and wastegate is moving and in good order.



The next stage is to examine the vacuum line and connections back to source and then ensure the vacuum supply is adequate.



If all is found to be well with those physical checks the cause of no boost is either the failure of one of the vacuum switches (or the electrical wiring or connections to them) or a fault condition exists that has caused the engine management to decide not to provide turbo boost.



In that case diagnostic equipment will be needed.

May 21, 2016 | Opel Cars & Trucks

1 Answer

Losing boost!! I have a 1993 mazda rx7 13b twin turbo with the stock turbos. When i punch it my boost goes up to about 10psi. But bleeds off and i can head it blowing out. Was thinking it was blow off...


Have you checked all the tubing cuplings? When mine was doing that i had a cupling that would keep sliding off just enuff that it was letting out air and loosing me boost.

Mar 29, 2012 | 1993 Mazda RX-7

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I have a 1994 honda civic dx and i want to install a turbo


make sure you have a good oil feed to the turbo and its not over boosting and the engine runs smooth through the boost stage

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1 Answer

Subaru Legacy GT CEL code 66


There is a differential pressure sensor mounted beside the 2wd fuse link with a couple of 5mm pressure lines going in each end. These lines connect to each turbo output. The two pressures acting on each side of this sensor produces a voltage read by the ecm which tells it the differential pressure between both turbo boosts during acceleration. Normally the primary turbo leads the boost and the secondary turbo plays catch up until the pressures are even then air valves get opened and shut to bring the second turbo compression in parallel with the first turbo. The two turbos simply act in sequence but function in parallel. Its just like having one big turbo but operating down two smaller paths.
The sensor measures the changing boost pressures as the second turbo rises to equal the first.
If the generated voltage is not what it expects it shows as a code 66. As you can start to see there could be many different reasons why there might be an imbalance in the two pressures.
It could be either turbo causing the imbalance or a faulty bypass valve or pressure relief valve or a number of other issues. It doesnt necessarily have to be a turbo or a solenoid which is faulty. All it means is that the pressure difference between the two boosts is wrong.
The real question is why is it wrong.
There is a lot you can do yourself to diagnose the cause. If you are able to study the manual which is available free off the internet (do a search for the link) then you will see that you can test many of the component parts quite easily at home and also temporarily replumb the turbos to bypass aspects of the system control to figure it out for yourself. To do this you will have to gain an understanding of how the twin turbo system works. However its not hard if youi strip away the complex jargon hiding simple functions.. There is a mystique of fear concerning working on these motors which is not justified.Just use common sense and logic.
Or you take it to a shop and pay someone else to do it for you.

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1 Answer

Just wondering if it possible to make the twin turbos on a 2002 legacy gt work at the same time like a single turbo instead of converting it to single turbo


The turbos are two different types.One is designed to start a bit lower in the revs and the other to come in when the revs are higher.Its called compounding boost.It can be changed but to put it on a sinlgle turbo would cost a fair bit.If you hot up the ones you have by recalibrating them and exhaust,you do get VERY big gains.The car is more driveable and you can get big boosts in power if the tuner knows what he is doing.Some really big horsepower units come from triple compounding turbos and the torque levels are extremely high.Hope this helps

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1 Answer

Check engine light comes on and goes...and no boost on turbo


all turbo vehicles can only make boost if induction system is sealed,at this stage rather than looking for a fault with actuator controls,i would check to see if all ducting(piping) is secure.from airfilter,intercooler,turbo etc to engine,just check that there are no leaks,if there are any loose,revving it on the spot to cut in turbo should cause a loud rushing of air.if this is all ok then we need to further.

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2 Answers

My sub


Importcarparts.com

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look for the turbo under the hood it looks like a snail kinda

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1 Answer

No boost


Check all the rubber hoses to and from the inner cooler for cracks, make sure all the clamps are tight.

Jul 24, 2008 | 1997 Subaru Legacy

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