Turbo activates very late | VCDS log - help

dtr

Member
Joined
Feb 19, 2018
Location
UK
TDI
2009 Passat B6, 2007 EOS 2.0TDI
Hi, I have VW with 2.0TDI BMM engine and it was never quite right with the boost but now things got to a point they can't be ignored any longer.

I've done a VCDS log in 3rd gear. I've only started from 1800rpm for safety resasons on a short and busy stretch but you could imagine turbo sitting all the way until then below 1100.
The graph on the right is just a normal DSG accelleration for comparison.
Also there are NO engine error codes or EML except one isolated occasion of flashing coil.



Full log is available here (middle rows is the 3rd gear)

https://drive.google.com/file/d/1XsnsyHyf-YiVV_8BuuVdIVGccmTxrzKb/view?usp=sharing

It is obvious turbo spools up way too late and I have to force the car into higher gear first to accelerate. Cat is gutted and there are very weird airy sounds when accelerating.

I have done the turbo actuator test with VCDS and the arm is clearly moving back and forth, but actual pressure doesn't change at 1400rpm.

I've checked the hoses from N75 to and the actual actuator hold pressure well. I had spare brand new MAP sensor and it didn't change anything at all.

Full boost system air leakdown test would be nice but I have no means and my usual mechanic has no interest other than going for full turbo replacement straight away. If someone in the Midlands UK area could help I'd appreciate.

Is there any way to tell from the graphs if the turbo is at fault or maybe an air leak somewhere.
If I can do anything else with VCDS or basic tools I am happy to try. Anything further will need someone better equipped to take over - happy to discuss all options!
 
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dtr

Member
Joined
Feb 19, 2018
Location
UK
TDI
2009 Passat B6, 2007 EOS 2.0TDI
The rod appears to move smoothly and responsively enough to my untrained eye. I couldn't see if it moves all the way to the end with a pocket mirror - it would stop at around 17inHg-ish.

I've got a bottle of Forte Turbo cleaner. I wonder if it worth a shot or best saved for another time?
 

dtr

Member
Joined
Feb 19, 2018
Location
UK
TDI
2009 Passat B6, 2007 EOS 2.0TDI
When does it start to move? Could be a lazy N75 or bad tunes or vacuum.
It moves very happily at 1400rpm with VCDS basic settings 'test'
Unless of course it doesn't move far enough which I couldn't 100% confirm yet

when driving I am simply not sure? unless you can tell from duty cycle in the graphs??

Brakes are a bit poo now but it is perhaps I got a tiny bit of air changing rear pads. Or it could be tiny bit of vacuum loss. I'll have to get it bled shortly one way or another.

Map is standard except DPF delete.
 

1854sailor

Resident Curmudgeon
Joined
Aug 10, 2004
Location
Westerly, RI
TDI
2015 Golf SE SportWagen, 2015 Golf SE Hatch Back.
...there are very weird airy sounds when accelerating...
Sounds like you have a boost leak. Check all of the hoses and seals in the charge air system, as well as the intercooler.
 

dtr

Member
Joined
Feb 19, 2018
Location
UK
TDI
2009 Passat B6, 2007 EOS 2.0TDI
Sounds like you have a boost leak. Check all of the hoses and seals in the charge air system, as well as the intercooler.
Possibly. Everything is a lot louder without cat so hopefully it is not just something I imagine. It sounds somewhat like a high pressure line initially somewhere in the middle left side of the engine bay. When the boost catches up the air noise is more or less gone.
Could be even leaky exhaust manifold for all I could imagine but I can't see any soot from the top without removing EGR and many other bits. So it could still be almost anything.

I'll have to find someone reputable to do the tests as I'm not sure I can handle this myself on a driveway and without a compressor.
 

1854sailor

Resident Curmudgeon
Joined
Aug 10, 2004
Location
Westerly, RI
TDI
2015 Golf SE SportWagen, 2015 Golf SE Hatch Back.
If you can hear a whooshing sound, the leak is probably big enough that you can see it. Look for a tell-tale oily film on the hoses and connections.
 

POWERSTROKE

Top Post Dawg
Joined
Jul 17, 2000
Location
Staten Island (The Dump)
TDI
2002 Golf
Put your finger in the actuator rod with a mityvac on it. See if it starts and goes through it’s tracel smoothly. If it is getting stuck at the beginning of its travel, which is very possible, you will get delayed boost.
 

1854sailor

Resident Curmudgeon
Joined
Aug 10, 2004
Location
Westerly, RI
TDI
2015 Golf SE SportWagen, 2015 Golf SE Hatch Back.
The OP says that he can hear what sounds, to me at least, like a boost leak. That's where I'd start. Just my 2¢...
 

dtr

Member
Joined
Feb 19, 2018
Location
UK
TDI
2009 Passat B6, 2007 EOS 2.0TDI
True. Checking the function and the smoothness of the actuator. It’s one of the simplest things to eliminate. Let’s see what he comes back with.
I had a play this morning.

The first push with the tool gives very faint creaking sound - it feels almost normal with the finger on the rod though - and then it is very smooth from there on. It returns back to 0 very very easily and smoothly.

I think it stops moving at at 15.5 inHg if the chinese tool scale could be trusted.

I may try this on my 2009 CR Passat to compare if it the actuator is similar as it has electronics right on top so may not be applicable? Edit: no, I can't get a feel of the rod in a Passat. It is very different.

Yesterday I put a bottle of Forte in the car and went for a good drive. Maybe it is now marginally pulling better but there is little in it. The airy sound is definitely there.
 
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