no boost

[Pirvu Eugen]

Massive vacuum!!!! Blocked air filter or again...turbo seized..

[UrS4boy]

With diaphragm broken....you will have boost. Only if the turbo is not spinning or the wastegate stuck open you have no boost..

I was grasping at "straws". You are right. If the wastegate diaphragm was ripped, there would still be spring pressure-based boost. As you say, assuming that the turbo is spinning and the wasteagate isn't stuck open. Based on the design of the exhaust system, the turbo will always be spinning at least a bit, even at idle. Which is why the engine vacuum on a turbo 20VT /3BAAN/ABY/ADUat idle is also less than it would be on a 7A at the same RPM.

Easy to check the turbo by removing the MAF to turbo inlet hose and seeing if the compressor (and turbine) can spin or not.

[newsh]

no boost

If the WG diaphragm is ripped the WG will not open and there will be way too much boost.

Derek says the turbo spins ok but I'm not sure if he's looked at the hot side.

[Pirvu Eugen]

Air intake blocked then....air filter, maf...
How bad the hot side of the turbo has to be to not produce any boost at all....

[Error404]

I would think WG jammed open / spring broken or turbine wheel is dead / MIA

[GazzaG60]

seen this before.

either. no boost hose on turbo, ic endtank destroyed (both unlikely) or broken turbo shaft or wheel.

happened due to oil starvation on 5 pot volvo twice. new unit lasted about 10 miles.

[Bowie69]

Given you have 'massive vacuum up to 2000rpm', I am going to say an air filter that has collapsed, or a blocked/collapsed cat (maybe).

Do the cheap/easy one first.

[DEREKCO]

No boost

OK guys I am a mechanic of 42 years MAF hose off engine runs turbo spins ,it drives OK till 2000rpm anything above that it does not boost the turbo is not broken or seized ,I have pressurised all hoses no holes or leaks the DV valve works when I pressurised intake hose and intercooler ,it gives no hint of any boost the idle stabilisation valve is work no leaks , if that is the case no boost at all means the wastegate is stuck open ,correct me please.Derek

[DEREKCO]

No boost

Sorry guys I get vacuum when driving off NOT up to 2000rpm as I pick up speed the vacuum drops as I accelerate hard gauge reads 0 no boost no matter how hard I accelerate boost is at 0 ,forget about the massive vacuum .The car starts fine ticks over fine drives fine no misfire or lumpy tickover just no boost

[DEREKCO]

No boost

Also new air filter fitted

[dbojar]

If You checked all pressure hoses and are ok, so You have no pressure in it. Check WG, turbo and ex manifold.

Wysłane z mojego GT-I9505 przy użyciu Tapatalka

[UrS4boy]

Some thoughts

You can test if there is an issue with a tear in the diaphragm or the wastegate sticking open, by trying to pressurize the wastegate chamber from below (via the blue "line" in the diagram below)



Disconnect the hose that goes to be bottom of the wastegate chamber from the N75 WGFV and try to pressurize the chamber (Mity Vac in pressure mode, etc). If you can't pressurize the chamber, then you can confirm whether it is the wastegate diaphragm or the wastegate valve by applying a vacuum to the nipple on the wastegate cap. If the wastegate diaphragm is good, you will be able to hold a vacuum and the issue is the wastegate valve. If not, the diaphragm is torn (very unlikely)

[quattro-nick]

remove the intake hose from throttlebody and give full throttle with engine running so you can feel whether the turbo blows or not,maybe you have a blocked ic?
you also can remove the waste gate flexi to see if this is not loosing exhaust gases when engine is running on idle or with some given throttle
maybe a blocked catalyst may also be the cause but that does not explain the large vacuum
i hope this help

[newsh]

OK guys I am a mechanic of 42 years MAF hose off engine runs turbo spins ,it drives OK till 2000rpm anything above that it does not boost the turbo is not broken or seized ,I have pressurised all hoses no holes or leaks the DV valve works when I pressurised intake hose and intercooler ,it gives no hint of any boost the idle stabilisation valve is work no leaks , if that is the case no boost at all means the wastegate is stuck open ,correct me please.Derek

Have you seen the hotside of the turbo? Are you 100% sure the wheel is there?

You can easily take the WG cap off and have a look, see if the valve is jammed open or the spring broken.

[Error404]

If you have 0 bar on the boost gauge, this is atmospheric pressure, indicating WOT with no boost, not vacuum.
Id first check the WG, if that seems fine, remove the down pipe and check the turbine wheel