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The mkiv Supra Owners Club

No second turbo :(


Thorin

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Went out for a bit of a drive this morning, accelerating up to the point where the 2nd turbo should kick in I was hitting 0.65-0.7 boost. At the point where the second turbo should come in it briefly rises to 0.75-0.8 but then drops back down to 0.65 again. :(

 

Now is this...

 

a) boost leak somewhere

b) fubar turbo

c) something else?

 

I'm praying for A. Other than the lack of boost car seemed normal, didn't notice any smoke out the back or anything like that. Not happy.

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Originally posted by Alex Holdroyd

Sounds like a leak to me...check all the small hoses towards the back...not just to see if they are connected but also for splits.

 

Thats what I'm hoping it is anyway. I had a quick look earlier and couldn't see any that had popped off, but it's too dark to have a proper look now. Which hoses should I be checking as the main culprits?

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Originally posted by GavinL

misread your sig "UK Spec Brakes"

 

In that case the second turbo could well have blown :D

 

I hope not! Just thought, could this be caused by a holed intercooler? Just that as I was looking around earlier I noticed that my IC really is fooked now and in need of a new one.

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Ok so I presume that the large pipe going off into the wing goes to the IC? And I also presume that oil residue being present inside that pipe means my turbo is shafted. :mad:

 

How much is a new turbo from Toyota or has anyone got one for sale? Also how big a job is it to do, so I can have an idea as to how much it's going to cost me to get done.

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Yep that is the IC pipe, however, I remember being told to expect some oil residue from the turbos when I was worried about seing deposits around the stock BOV. As long as it is a residue and not a torrent, I would assume one of those (extremely hard to get to) tiny hoses has sprung a leak.

 

Guys, apart from loss of boost, isn't there usually some other big indicator suggesting loss of the #2 turbo? Like smoke, excessive noise?:(

 

Just my 2cents worth...

 

Rgds,

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Originally posted by Thorin

Ok so I presume that the large pipe going off into the wing goes to the IC? And I also presume that oil residue being present inside that pipe means my turbo is shafted. :mad:

 

How much is a new turbo from Toyota or has anyone got one for sale? Also how big a job is it to do, so I can have an idea as to how much it's going to cost me to get done.

 

calm down .....oil in the IC pipes is usual....you will give yourself a coronary at this rate!

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Originally posted by Thorin

Well I'm buggered if I can find any pipes off or leaks anywhere. Bloody car.

 

I have now had 3 cases wher the butterfly valve that diverst gasses between turbos has failed mechanically. Probably not a job you'd want to attack yourself, some tricky dismantling and perfectly accurate and heat shielded TIG welding required. Look down at where the turbo elbow meets the downpipe, there's a metal canister there with a small vac hose to it. It operates the valve in the elbow section via a quadrant, see if the quadrant has become detached from the rod it turns. There are ceramic parts within, and the assembly if bought new is VERY expensive.

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Originally posted by Chris Wilson

I have now had 3 cases wher the butterfly valve that diverst gasses between turbos has failed mechanically. Probably not a job you'd want to attack yourself, some tricky dismantling and perfectly accurate and heat shielded TIG welding required. Look down at where the turbo elbow meets the downpipe, there's a metal canister there with a small vac hose to it. It operates the valve in the elbow section via a quadrant, see if the quadrant has become detached from the rod it turns. There are ceramic parts within, and the assembly if bought new is VERY expensive.

 

Ok Chris stop upsetting me :(

 

Er, I'll have to have a look for this metal canister thingy, what the hell does a quadrant look like? I'll have a look in the morning.

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Originally posted by Chris Wilson

I have now had 3 cases wher the butterfly valve that diverst gasses between turbos has failed mechanically. Probably not a job you'd want to attack yourself, some tricky dismantling and perfectly accurate and heat shielded TIG welding required. Look down at where the turbo elbow meets the downpipe, there's a metal canister there with a small vac hose to it. It operates the valve in the elbow section via a quadrant, see if the quadrant has become detached from the rod it turns. There are ceramic parts within, and the assembly if bought new is VERY expensive.

chris do you mean this part

it has a small butterfly inside

 

was not sure weather to take the arm off to poilsh it up

there is a small cannister on top where a vacuum pipe goes to.

it looks like some sort of actuatar.

 

image

 

image

 

 

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Try

This picture

It's as good a shot as I could get. You can see a tiny bit of the vac hose (blue in this piccy as I replaced the black on that kept popping off) on the right, it connects to the coke-can sized actuator for the exhaust gas control valve. An arm comes out of it to the exhaust pipe, which controls the valve inside.

 

This section of exhaust mixes the streams from the two turbos. The valve is shut when only turbo 1 should be online, thus preventing turbo 2 from experiencing exhaust flow. It opens up around 3500-4000rpm and allows the turbo to spin and create boost.

 

If this is indeed buggered on yours, I have a whole assembly - exhaust section (with the butterfly valve in it), arm, and actuator - spare for velly good plice :)

 

However, I don't think it's this as when the intake air control valve opens to allow the airflow from turbo 2 to enter the intake stream, if turbo 2 isn't turning it doesn't add any air. that in turn means the airflow from turbo 1 takes the path of least resistance and heads down the throat of turbo 2 and spins it backwards! That's the symptoms you get if the wee hose on the EGCV pops off, so it will be what happens if the the actuator arm has failed as well - same result, the butterfly flap doesn't open.

 

You are getting what seems to be full pressure of turbo 1 with a small loss in the system somewhere, and turbo 2 not doing anything. Try the intake air control valve

IACV

It's the VSV with two blue hoses and brass-coloured actuator bit, just down and right from the centre.

 

Also check the resources area of this site for piccies and descriptions of the turbo hoses and a pressure map diagram.

 

-Ian

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