A very good and generous friend of mine has VCDS, so logged my car accelerating in 3rd from a rolling start to check pressure and see if we can get a HP estimate.

 

Out of the logs we produced some charts. I've no doubt my DV has a gaping hole in it!!!

 

Think I'll get back those missing 20HP when it's fixed? Looks like at around 3000rpm, something just lets go and the pressure plummets! 

 

No idea why I'm sharing.....just thought they were interesting graphs! Maybe someone else will.

 

Any comments from those more experienced with these kinds of things? (car is booked in for a full service and DV replacement)

 

 

 

 

 

 

 

 

 

Are you sure those boost pressure charts are in mbar?

 

I would of expected circa 1400 - 1600 mbar before deducting atmospheric pressure.  But the charts do not show any  significant under delivery of boost relative to specified boost, so I don't think they show a diverter valve leakage problem anyway. The downward slope surprises me a bit but the specified boost follows the same slope. It doesn't appear to be scaled in mbar though so not sure we are looking at the right plots.. 

Are you sure those boost pressure charts are in mbar?

 

I would of expected circa 1400 - 1600 mbar before deducting atmospheric pressure.  But the charts do not show any  significant under delivery of boost relative to specified boost, so I don't think they show a diverter valve leakage problem anyway. The downward slope surprises me a bit but the specified boost follows the same slope. It doesn't appear to be scaled in mbar though so not sure we are looking at the right plots.. 

 

Ah ok, I may have used the wrong units there. I'll double check.

 

Why would the specified be doing that? I don't understand why it's requesting drops so suddenly? It's not right is it?

If your turbo is the K03 they struggle to produce boost higher up. If the specified boost was higher you would end up damaging the turbo very quickly.

Ah ok, I may have used the wrong units there. I'll double check.

 

Why would the specified be doing that? I don't understand why it's requesting drops so suddenly? It's not right is it?

Boost becomes lower at higher RPMs.

 

The engine requires less boost and the engine and turbo may not be able to cope with higher boost at high RPMs. So that is how they are programmed.  

 

The downward slope steepness without any plateau looks a bit different to what I would expect but given the confusion of units, it is hard to be categorical or whether the units or scale is distorting. The blue line, specified boost, is effectively one of the engine ECU map parameters. In the plots you have, the actual delivered boost follows the requested boost very closely, with a slight characteristic overboost as boost builds at the start.  That is what is normally expected.  Hence my first comment that it doesn't look like a diverter valve is losing boost.

 

If you search Golf Mk5 GTI or Octavia VRS TFSI or EA113 boost plots, boost graphs etc. You will find some plots to compare.

Boost becomes lower at higher RPMs.

 

The engine requires less boost and the engine and turbo may not be able to cope with higher boost at high RPMs. So that is how they are programmed.  

 

The downward slope steepness without any plateau looks a bit different to what I would expect but given the confusion of units, it is hard to be categorical or whether the units or scale is distorting. The blue line, specified boost, is effectively one of the engine ECU map parameters. In the plots you have, the actual delivered boost follows the requested boost very closely, with a slight characteristic overboost as boost builds at the start.  That is what is normally expected.  Hence my first comment that it doesn't look like a diverter valve is losing boost.

 

If you search Golf Mk5 GTI or Octavia VRS TFSI or EA113 boost plots, boost graphs etc. You will find some plots to compare.

 

 

 

Many thanks!

 

I've put the raw data online - I have done something funny with the mbar in the formula.

 

https://drive.google.com/file/d/0BxGeSs6ygIrdYlVITW1HXzFGVm8/view

 

 

Does the raw data give anything away?

OK.

 

Your raw data is then enhanced by formulas at the side. In the formulas for actual and specified boost, there are calculations that remove 1013mbar (atmospheric) and /14.5 which is an approximation of Bar:PSI. [edit: 14.5 is correct conversion]

 

So, your boost is in PSI and is with Atmospheric excluded. Which is a decent way of presenting it.

 

I stand by the fact that it looks ok. I think the long downward slope is probably due to the presence of a lot of high RPM all the way to 6,800 plus.  Most people when looking at boost look at the operating range probably between, 1,800- 3,500 or 4,000. That is where most of the turbo action is. If you plot up to that RPM range only the graph will look flatter and you will see more of a plateau.  

 

Peak boosts of 10psi+ and holding 7psi until after 4,000 rpm seem in line with expectations to me.

 

I'd be surprised if your DV is faulty looking at this. 

Edited 6 January, 20179 yr by TheClient

OK.

 

Your raw data is then enhanced by formulas at the side. In the formulas for actual and specified boost, there are calculations that remove 1013mbar (atmospheric) and /14.5 which is an approximation of Bar:PSI. [edit: 14.5 is correct conversion]

 

So, your boost is in PSI and is with Atmospheric excluded. Which is a decent way of presenting it.

 

I stand by the fact that it looks ok. I think the long downward slope is probably due to the presence of a lot of high RPM all the way to 6,800 plus.  Most people when looking at boost look at the operating range probably between, 1,800- 3,500 or 4,000. That is where most of the turbo action is. If you plot up to that RPM range only the graph will look flatter and you will see more of a plateau.  

 

Peak boosts of 10psi+ and holding 7psi until after 4,000 rpm seem in line with expectations to me.

 

I'd be surprised if your DV is faulty looking at this. 

 

Many thanks for checking that out for me.

No Worries.

 

Following on what I was saying about RPM range,. This is your run 1 data with a shorter rpm range selected and you'll see it looks a bit flatter and there is more of a plateau visible of relatively stable boost visible up to about 3,600-700 rpm before starting to recede.

 

Here's my stage 1 TFSI boost plot for comparison, atmospheric not deducted.

Thanks guys, really appreciate it.