Hey folks,

Got a problem with my boost, seems I have far too much of it.

Upon accelerating I'm sure I got some kind of fuel cut or over boost. I seen the boost had spiked up to 1.8 bar and 90% on the solenoid (AVCR boost Controller).

Tried again, but a bit gentler on accelerating and boost was going well above the 1.5 bar which it is set at.

So I put the AVCR setting to OFF so that it would boost on wastegate pressure but i was still boosting far too high.


My question is, I suspect the actuator is seized or jammed hence giving me lots of boost, so with the engine off i tried to move it by hand. Should I be able to move the actuator on the turbo by hand? Do i need to put an alternative air pressure supply onto it to test it? or is it jammed/seized as suspected?

Thanks for any info/advice on this

Rich

 

What turbo are you running? Have you checked the boost control pipework for splits or bad fitting, any leaks in the boost control pipework will cause your symptoms.

Cheers Iain

 

Hi Iain,

Its a TD05 20G turbo.

I initially checked all hoses to see they were all connected which they were but I never looked closely enough to check for any splits, I'll do that today and report back

Thanks

Rich

 

Take a clean pipe and connet one end to the actuator and one to the compressor housing.

This should then produce 0.5 bar of boost. If it does, there's a problem within the pipework and if it doesn't, theres an issue probably with the actuator.

 

Hi I had the same problem it sounds like turbo creep and it's the waste gate valve on the turbo not shutting fully after boost hence it creeping up over it's normal amount of boost

 

If it didn't shut you'd make less boost...

Mine is wedged shut by the ( stupid APS ) exhaust system and makes 2 bar all the time.

dunx

 

Found a burst pipe, typical its in an awkward position on the turbo compressor housing.

Glad its an easy fix but if it was the actuator/wastegate then it would have been a good excuse to get it rebuilt.

So my understanding is that the boost from the compressor housing is fed to the boost solenoid then a feed from that goes back to the actuator on the turbo. With no feed to the solenoid then there was no output air pressure from the solenoid to the actuator. With no air signal on the actuator then the wastegate would remain closed and hence producing the maximum boost that the turbo can achieve?

Thanks for all your advice gentlemen

Rich

 

That is basically correct mate, the turbo produces the air pressure required to operate the wastegate actuator, if you imagine the solenoid was switched off, the pressure from the turbo would go straight through the solenoid to the actuator which would limit your boost to whatever your actuator spring rate is (wastegate pressure), what the solenoid does is bleeds off a controlled flow of air from the actuator system which keeps the pressure in the actuator system below the actuator spring rate so the wastegate remains closed until the target boost pressure is achieved.



Cheers Iain

 

Yes but it over boosts to compensate for the loss of boost

 

No!
It over boosts because the pipe is split. There is no 'loss' of boost pressure. In fact, in this situation, the turbo will boost to destruction. Not to compensate for any thing, simply because the control system has a fault.

 

No because all pipes actuator and everything checked so only thing it will be is the waste gate not shutting properly

 

 

Replaced my burst pipe/hose today and the car is running normal again.

I had excess vacuum hose running to the dump valve so robbed about 100 mm length from there. The hose that was split came off the turbo and onto a connector which then fed another hose back to the boost solenoid so only needed a small piece.

Very fiddly job as I ended up romoving the intercooler pipework and filter/maf to get access to the turbo housing connection.

Post no.10 is correct

Cheers

Rich