hi there ive got a problem with my mk8 ST sadly ive been trying to ask everywhere even searching on google for the problem but no luck i want to know the problem before sending it off to a mechanic but i get very rough idle on start up and shortly after it will completely stall the only thing i can see at the moment is the turbo throttle elbow that goes onto the rubber pipe onto the intercooler it seems like that pipe is squeezing itself with suffocation that indicates that there is some sort of air issue aslong this section would be this a throttle body issue and possibly need a new one as i did get all the sensors and they seem to be ok ie not cracks etc.

 

thank you liam 

Sounds like it could just be a faulty pipe.  They aren't solid rubber, they have an internal structure that should prevent them sucking in under vacuum.  If the pipe is collapsing internally, that will restrict the flow through the MAF.

We can't access Mk8 parts catalogues so I'm not sure which pipe it is.  Have you got a picture?

10 hours ago, Liam xarter said:

hi there ive got a problem with my mk8 ST

Does your profile need updating ????? 🤔

28 minutes ago, unofix said:

Does your profile need updating ????? 🤔

yes it does sadly as i only made an account last night 

 

45 minutes ago, TomsFocus said:

Sounds like it could just be a faulty pipe.  They aren't solid rubber, they have an internal structure that should prevent them sucking in under vacuum.  If the pipe is collapsing internally, that will restrict the flow through the MAF.

We can't access Mk8 parts catalogues so I'm not sure which pipe it is.  Have you got a picture?

ive attatched a photo where the throttle elbow is and it connects to the rubber hose and clamp that goes all the way to the intercooler that rubber hose is where the air is getting restricted and squeezing itself i do have a video but cant send it through here.

Hmm, ok.  That photo is very small on a laptop but I think it's the long intercooler pipe on the right hand side of that diagram?  Then the TB is connected directly to the inlet manifold?

As that pipe is 'before' the throttle body in the intake tract, I don't see how the throttle body itself could be causing excess vacuum inside that pipe.  There must be a restriction before that.  Potentially in the intercooler but that's almost impossible unless something was accidentally dropped in there while the pipes were open.  Potentially the air filter is clogged up or something like a crisp packet has been sucked into the airbox from the road?  (Unsure how large the intake holes are at the front on these)  Either way, I think I would be looking at the air box and filter next.

 

I've also had a quick look at used engines on ebay as not very familiar with this engine.  There appears to be some sort of additional air pipe between the turbo inlet and outlet pipes with a valve on it.  That valve could potentially be restricting the inlet flow if it's designed to allow non-charged air to bypass the turbo when boost isn't required, such as at idle speed.  That is only a rough theory though, if anyone can confirm exactly what that valve is for that would be ideal.

5 minutes ago, TomsFocus said:

Hmm, ok.  That photo is very small on a laptop but I think it's the long intercooler pipe on the right hand side of that diagram?  Then the TB is connected directly to the inlet manifold?

As that pipe is 'before' the throttle body in the intake tract, I don't see how the throttle body itself could be causing excess vacuum inside that pipe.  There must be a restriction before that.  Potentially in the intercooler but that's almost impossible unless something was accidentally dropped in there while the pipes were open.  Potentially the air filter is clogged up or something like a crisp packet has been sucked into the airbox from the road?  (Unsure how large the intake holes are at the front on these)  Either way, I think I would be looking at the air box and filter next.

 

I've also had a quick look at used engines on ebay as not very familiar with this engine.  There appears to be some sort of additional air pipe between the turbo inlet and outlet pipes with a valve on it.  That valve could potentially be restricting the inlet flow if it's designed to allow non-charged air to bypass the turbo when boost isn't required, such as at idle speed.  That is only a rough theory though, if anyone can confirm exactly what that valve is for that would be ideal.

it does have the mountune air filter so i may put the paper filter in to see if that changes anything but yes its along that side of the pipe where its not liking the air delivery and it does do a small squeek along that side aswell when you turn the engine off before it stalls so possibly a leak in the pipe? i did ring up ford about that pipe which isnt cheap by all means 

15 minutes ago, Liam xarter said:

it does have the mountune air filter so i may put the paper filter in to see if that changes anything but yes its along that side of the pipe where its not liking the air delivery and it does do a small squeek along that side aswell when you turn the engine off before it stalls so possibly a leak in the pipe? i did ring up ford about that pipe which isnt cheap by all means 

If there was a leak it could just suck the extra air from outside rather than crushing the pipe.  A split in that pipe would generally cause big problems under boost as well, so I'm not convinced it's that.

The Mountune filter shouldn't be causing any problems itself.  Though it does create the opportunity for someone to have dropped a piece of tissue or plastic wrapping into the intake while the filter was removed.

Does it have any upgraded pipework or is it just the filter that was replaced?

 

There are loads of used MK8 ST engines on ebay so it shouldn't be difficult to find a used intercooler pipe if you do want to try replacing that.

2 minutes ago, TomsFocus said:

If there was a leak it could just suck the extra air from outside rather than crushing the pipe.  A split in that pipe would generally cause big problems under boost as well, so I'm not convinced it's that.

The Mountune filter shouldn't be causing any problems itself.  Though it does create the opportunity for someone to have dropped a piece of tissue or plastic wrapping into the intake while the filter was removed.

Does it have any upgraded pipework or is it just the filter that was replaced?

 

There are loads of used MK8 ST engines on ebay so it shouldn't be difficult to find a used intercooler pipe if you do want to try replacing that.

it has the mountune rear intake silicone pipe and mountune turbo elbow and of course the mountune airbox and i did contact them yesterday and told me this wouldnt cause the issue and i double checked all the pipe work i installed and theres 0 leaks all of it is very tight and secure im sort of running out of ideas what it is 

Ah ok.  In that case, there could be a restriction in one of those parts.  Personally I'd disconnect the turbo intake elbow so it's just open to air and try idling it.  If the IC pipe doesn't suck closed then the problem definitely lies before the turbo in one of the new parts.  Obviously take care not to suck anything into the turbo while the intake is off.

2 hours ago, TomsFocus said:

Ah ok.  In that case, there could be a restriction in one of those parts.  Personally I'd disconnect the turbo intake elbow so it's just open to air and try idling it.  If the IC pipe doesn't suck closed then the problem definitely lies before the turbo in one of the new parts.  Obviously take care not to suck anything into the turbo while the intake is off.

hi tom ive just done what you recommended to me to do so the car throttle is fine and the tube isnt squeezing so when the throttle body is disconnected soon as i bolt it back up the problem comes back is this a sensor or a throttle body replacement ? 

4 minutes ago, Liam xarter said:

hi tom ive just done what you recommended to me to do so the car throttle is fine and the tube isnt squeezing so when the throttle body is disconnected soon as i bolt it back up the problem comes back is this a sensor or a throttle body replacement ? 

Not a sensor or TB fault.  There must be a physical restriction in the pipework somewhere before that pipe. 

If the aftermarket pipes and filter have only just been fitted, I would check inside them for any packaging plastic or paper or even a bit of latex glove.  The pipes themselves shouldn't cause a restriction as they are made for the car, but there could easily be something loose inside them that shouldn't be there. 

You could also take off the bottom hose from the intercooler pipe on the other side as if there was something in the pipes after the turbo, that is where it will get stuck on that side of the intercooler.

4 minutes ago, TomsFocus said:

Not a sensor or TB fault.  There must be a physical restriction in the pipework somewhere before that pipe. 

If the aftermarket pipes and filter have only just been fitted, I would check inside them for any packaging plastic or paper or even a bit of latex glove.  The pipes themselves shouldn't cause a restriction as they are made for the car, but there could easily be something loose inside them that shouldn't be there. 

You could also take off the bottom hose from the intercooler pipe on the other side as if there was something in the pipes after the turbo, that is where it will get stuck on that side of the intercooler.

right ok just that ive looked in the airbox its all clean i even put the paper filter back in just that the error code and the suffocation of air  only appears when that elbow its screwed back into the housing on the throttle body the charge pipe end hot side theres no leaks there only thing i havent checked is the rubber hose end there it connects to the intercooler so that might be the best bet to look but i did give it a wiggle anyway when the airbox was out but i will take a look just incase sorry if im being a pain at all just this issue is very questionable to where the leak is 

1 minute ago, Liam xarter said:

right ok just that ive looked in the airbox its all clean i even put the paper filter back in just that the error code and the suffocation of air  only appears when that elbow its screwed back into the housing on the throttle body the charge pipe end hot side theres no leaks there only thing i havent checked is the rubber hose end there it connects to the intercooler so that might be the best bet to look but i did give it a wiggle anyway when the airbox was out but i will take a look just incase sorry if im being a pain at all just this issue is very questionable to where the leak is 

There isn't a leak at all.  If there was a leak, the pipework wouldn't be able to crush, it would just suck air in through the leak instead. 

The engine will suck a certain amount of air all the time (the size of the cylinders multiplied by the number of revolutions per minute).  If it can't suck enough air through the pipework from the grill intake, through the airbox, through the turbo and through the intercooler, it will start to suck in the soft pipes until it completely runs out of air and stalls because there is no longer enough air to fill the cylinders.

So we are looking for a large physical object blocking up part of the pipework somewhere.  Not a leak.

2 hours ago, TomsFocus said:

There isn't a leak at all.  If there was a leak, the pipework wouldn't be able to crush, it would just suck air in through the leak instead. 

The engine will suck a certain amount of air all the time (the size of the cylinders multiplied by the number of revolutions per minute).  If it can't suck enough air through the pipework from the grill intake, through the airbox, through the turbo and through the intercooler, it will start to suck in the soft pipes until it completely runs out of air and stalls because there is no longer enough air to fill the cylinders.

So we are looking for a large physical object blocking up part of the pipework somewhere.  Not a leak.

im gonna have another look again tomorrow as i do agree with you something is blocking some part of the air flow up ill keep you updated