No Boost - Help!!

S

SteveSmith

Active member
Hi all,

Yesterday I lost all boost! Flat out, changed gear and I lost all boost.

I’m hoping it’s nothing too serious as it felt like a boost hose popped off or something.

I can’t see any obvious loose hoses and due to having no boost what so over I’m guessing it’s not a split hose.

The turbo is still spoiling but it’s as if the divertor valve is stuck open or the wastegate it stuck open.

Can anyone tell me if this wastegate is stuck open?

474C5A07-710E-46FC-A9B3-B74D9ABCFDD4.jpeg

Any help or advice would be appreciated! BMW can’t get the car in until Thursday!!
 
Be interested to see if the piggy back unit has anything to do with it?
 
Hi, just taken this pic of mine for you, I’ve heard of the solenoid failing on these electronic waste gates before :?
F5136CD8-E8FD-4ECF-9378-D7A18490393D.jpeg
Rob
 
Smartbear said:
Hi, just taken this pic of mine for you, I’ve heard of the solenoid failing on these electronic waste gates before :?
F5136CD8-E8FD-4ECF-9378-D7A18490393D.jpeg
Rob
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You legend. Is that with engine off? Does it change when the engine is running?

If it’s not the wastegate then it might be the diverter valve. Hopefully!
 
Hi Steve, that's with the engine off & I'm not sure but assume the wastegate opens with load and not rpm to bleed off boost?
Rob
 
Smartbear said:
Hi Steve, that's with the engine off & I'm not sure but assume the wastegate opens with load and not rpm to bleed off boost?
Rob
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Half correct Rob, works off compressor pressure opening it. It bleeds off exhaust gasses back into the exhaust not boost though as the wastegate is mounted on the turbine housing not the compressor housing. The turbo actuator gets boost pressure from the compressor wheel and when this builds enough it overcomes the vacuum in the actuator thus forcing it to move, which in turn pushes the actuator rod attatched and opens the wastegate on the turbine housing.
 
SteveSmith said:
john-e89 said:
SteveSmith said:
Should it move freely when not running??
Click to expand...

Yes, it’s just mechanical. The actuator is vacuum operated but it should all move freely.
Click to expand...

That is the issue then as it definitely is t moving freely!
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If possible try getting a pair of long nose pliers or a small hammer and either pull it shut or tap the actuator rod on the wastegate end. Might just be stuck and needs a tap to free it off.
 
john-e89 said:
SteveSmith said:
john-e89 said:
Try moving the actuator rod by hand Steve, it may just need freeing off and lubricating.
Click to expand...

Should it move freely when not running??
Click to expand...

Yes, it’s just mechanical. The actuator is vacuum operated but it should all move freely.
Click to expand...

Hi John, I don’t think these are vacuum operated? The earlier cars had one like that but the lci models went to a solenoid activated wastegate. :?
Rob
 
Smartbear said:
john-e89 said:
SteveSmith said:
Should it move freely when not running??
Click to expand...

Yes, it’s just mechanical. The actuator is vacuum operated but it should all move freely.
Click to expand...

Hi John, I don’t think these are vacuum operated? The earlier cars had one like that but the lci models went to a solenoid activated wastegate. :?
Rob
Click to expand...

Yes I think you’re correct on that Rob.... :oops: My mistake. Sorry Steve, wrong year.

Cheers Rob, good spot, my bad.
 
No worries John, I think most of us learn something new about these cars every time we look on the forum :)
Rob
 
Waste Gates op mechs have changed a lot over the years .
The Saab turbo was operated by exhaust gas pressure on top of a diaphragm!
 
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