Boost tailing off too early and goin too low!

[prj]

If the throttle isn't fully open how do you get max boost at the start? my understanding of the ecu was unless it got the code for WOT that it wouldn't fully boost

Motronic has a 3D map for requested boost - RPM vs Throttle position.
So it depends how it is mapped...

On his car, if throttle did not go past say 80 degrees then exactly this would happen.

[s2tommy]

Well I think it's the waste gate now. After cleaning every up, the valve stem itself is badly scored one side/half and has a step at the top half way around to, the bass bush looks very rough! And I can see on the bottom flat surface of the valve you can see where it has been seating and half way around it is steped! So to me it's worn out and has been shutting at a slight angle. I will take some pics but don't know really how to get them on here has I only have a iPhone lol

[prj]

Yeah that makes sense. If it goes in at an angle it can stick half open and cause this problem.

[s2tommy]

Guys, when you are suggesting things, don't forget that this car has run properly and made the required boost in the past.
So it is not a fundamental flaw of something not operating at all - I have logs of this car making more than 2 bar boost to redline each and every time.

Tommy, I pm-ed you two things to check with VAG-COM... might want to do that before you take the whole car apart.

Btw, I think the throttle is not opening fully or the altitude sensor is shot.

I know the throttle is ok, because I fitted a new tps on Saturday and pluged it into vag com, at idel the lowest angle I could get was 7.4 7.5, I found on here that it should be 5-7 deg's. was thinking of needle filing the slotted holes and see if can get it within the 5-7 deg's??
And was getting 94% on foot pedal an 96% by hand.
Forgot totally aberter sensor! Sorry will look tonite hopfully
And I get different voltage on the tps car plug! Pin 1 & 2 = 4.96v pin 2 & 3 = 6.00v and I read these be both the same voltage give or take 0.5v

[Rusty]

So did this issue exist before you changed the TPS?

[Jamo]

Well I think it's the waste gate now. After cleaning every up, the valve stem itself is badly scored one side/half and has a step at the top half way around to, the bass bush looks very rough! And I can see on the bottom flat surface of the valve you can see where it has been seating and half way around it is steped! So to me it's worn out and has been shutting at a slight angle. I will take some pics but don't know really how to get them on here has I only have a iPhone lol

1st thing we said at the MRC RR day

[Jamo]

Motronic has a 3D map for requested boost - RPM vs Throttle position.
So it depends how it is mapped...

On his car, if throttle did not go past say 80 degrees then exactly this would happen.

Now that makes sense

[s2tommy]

So did this issue exist before you changed the TPS?

I don't really know when problem has started has its was mapped over 12 months ago now, at 2.3bar I don't really like taking my eyes off the road to look hard at boost gauge lol
I was having a issue with coming off throttle and to idel and when sat at a curtain rpm say 60 mph it would sputter an cut out! Got two fault codes both tps so removed and fitted a new unit. Hence checking on vag com after fittin new one. Drives lovely now just want more power what is rightly MINE lol

[prj]

If throttle shows 94 when you put your foot down, then everything is OK with it from ECU perspective. Don't worry about the angle so much on idle. As long as you hear a click from the close throttle switch when lifting it off fully then it's OK.

But since you found scoring on the wastegate, most likely this is the problem.

You can always check the altitude sensor for good measure - if it shows around 1000 its OK.