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The mkiv Supra Owners Club

Boost problem


Stonkin

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Hi guys, put this in here instead of Tech in the hope to get some quicker thoughts as my mechanic is waiting to try a few things.

 

I had my manifold removed and welded as it was cracked. Even with it cracked the boost controller would still run 1.0 and 1.4 bar on high and low boost. It was fixed and put back, but when i was given the car back it seems like the boost controller isnt doing anything, it doesnt make more than about 0.8 bar of boost, almost like its just off the waste gate spring. We then noticed the downpipe had a crack running round the pipe right next to the hot side of the turbo. So it went back and this has just been welded and rewrapped. Currently this is still off the car.

 

He is saying that if you were sat in the drivers seat looking at the hotside of the turbo (t61) spinning the blade anticlockwise it spins freely, spinng it clockwise which is the way he said it will spin there is a resistance there.

 

He is also wondering when the manifold has been welded if there is any welding marks on the inside which could be restricting flow.

 

He said he can take the manifold off to check with a camera.

 

The boost valve under the bonnet (apexi avcr) appears to be wired back up as it was. One side labelled NO goes to a T piece which 1 side splits to the compressor and the other side goes down to the wastegate. The other side of the apexi valve also goes down to the wastegate.

 

Its possible he could put the downpipe back now it has been welded and all is fine, but in trying to save labour costs, is there any other ideas that could be restricting boost?

 

Any quick ideas hugely appreciated :)

 

cheers guys

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Yeah that seems to be a common problem mate from doing a search. They are definetly connected as it was and how the diagrams on here show. It's back together but not being road tested till the morning.

 

Can only think there is a leak somewhere? Will be very surprised if it works properly after the crack in downpipe fixed.

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Have just been called. He has done a test of clamping a pipe. The one that comes out from the No side of the apexi valve, goes to a T piece which splits 1 side to the compressor and the other side goes down to the side port on the wastegate. He clamped it in between where it goes from the T piece down to the wastegate. Took it for a drive and it peaked very quickly at 1.6 bar but didnt fully rev it because of this.

 

Now i dont totally understand what this means, but he is saying there is therefore no problem with any work done when fixing the manifold/downpipe and putting everything back together.

 

With this pipe being blocked off surely the boost controller isnt doing its job, but the wastegate spring cant do its job either as its blocked off, hence why it would just keep boosting if you let it?

 

One thought i just had, when i put the emu back in the car and i put up a post not entirely knowing what this black power connector was

 

image

 

Could this be anything to do with powering the apexi valve, or would that come directly from the avcr?

Edited by Stonkin (see edit history)
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Still waiting to hear if this connector being plugged in has made any difference. Either way car is coming home tonight as the mechanic is blaming the boost controller and nothing mechanical.

 

Ive read that some controllers have a switch to change between internal and external wastegate, does the avcr have this? wondering if i have knocked it.

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It's an avcr mate. Got car back now, still only making 0.8 bar

 

was considering doing a complete reset on the avcr, but don't fancy setting the whole thing up again.

 

I've connected the laptop to the emu but can't see where I can check what the option 1 & 2 ports on the emu have been setup to connect to. Just wondering if the avcr should be plugged into option 2 instead of 1

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It's an avcr mate. Got car back now, still only making 0.8 bar

 

was considering doing a complete reset on the avcr, but don't fancy setting the whole thing up again.

 

I've connected the laptop to the emu but can't see where I can check what the option 1 & 2 ports on the emu have been setup to connect to. Just wondering if the avcr should be plugged into option 2 instead of 1

 

Drop Ian C a PM, he is pretty good with the EMU. :)

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Found in google where to check, under parameters, front panel. 1 is setup for greedy pressure sensor (which is where it is) and 2 as other, which will be the datalog as said before.

 

Tempted to turn the gain up on the 1 bar setting to see if it increases it above the .8 but there's no reason why I should have to do that is there.

 

This is doing my head in

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Battery was disconnected a few times yes, but I have done so loads of times and always keeps them. Have gone right through it and all still there.

 

Went out just now set at 1 bar, it made .78 , the gain set at 46%, I increased it to 51% and it made .84 which I thought was progress. Increased it to 63% and it stayed at .84 so definetly not that as that high increase in % should and always used to make a big difference. Now put back to 46% and giving in for the night.

 

It's going to AFR Saturday morning

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Been down at AFR today. The wastegate was removed and taken apart to inspect, it was given a clean inside and put back together and appears to be working ok. All vacuum pipes were inspected from the apexi valve, 1 was very hard and had a small slice in it. This was replaced and i would have put money on it working. Road tested and still the same!

 

We then replaced the valve with another apexi one, road tested, still the same. My valve and the spare were then checked out power wise and both were functioning fine.

 

The guys had a chat with Matt who has recommended he tries another boost controller on Monday. No idea what could have happened to mine, but it seems a good shout and i'm not sure what other options there are.

 

Anyone with any ideas, feel free to shout :)

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As an update on this, it seems the main issue is that the blades of the turbo are spinning freely one way, but spinning the way they should go there is a lot of resistance there.

 

Its weird that the car still makes .8 bar, infact i think Matt got it to just over a bar with the duty right up. There is no bad noises from the turbo, so not really making sense.

 

I had a chat with b'have earlier, get well soon pal :thumbs: , he explained how the turbo should have been removed and fitted when it was taken off to do the manifold before, i obviously dont know how it was done. Maybe something isnt together right here. I believe Dude is going to have a look.

 

Not sure if fitting a bleed valve as a test could be a good idea just to totally eliminate the boost controller?

 

Otherwise it could well be new turbo time in the hope that fixes it

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As an update on this, it seems the main issue is that the blades of the turbo are spinning freely one way, but spinning the way they should go there is a lot of resistance there.

 

I know this isnt the answer your looking for mate but is your turbo BB or journal type? A journal type should have slight resistance when spinning, BB turbos spin freely.

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In that case it does sound like the turbo, possible the bearing, is knackered then.

 

As i said journal bearings should have a little resistance a little bit like a viscous coupling so to speak, best example i can think of, but shouldnt be difficult to spin although they dont spin 100% freely.

 

Take a look at this video to see what i mean :)

 

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