Hi All,

Been trying the solve my turbo problem for a few weeks now and was wondering if anyone can suggest any advice?

2004 Superb.

My problem started back in December engine light coming on, emission workshop up on the display and the dreaded limp mode and loss of power.

Fault code on VCDS is 17964 charge pressure control - negative deviation - intermittent.

What I have tried so far: replaced N75 with a new one & two doses of Mr Muscle into the turbo, I can move the turbo actuator with my finger( it's stiff but it moves up then down).

The engine light has cleared on its own over the last few weeks but always come back, did 7 miles the other day and the car was pulling like a train right up the rev range. On the return leg home first time I put my foot down in 3rd at 3200rpm ish light came and lost power..have noticed this a few times 3rd gear and 3000ish rpm activating the fault.

Any suggestions what to check next? I have a VCDS so can do some live logging.

Try the boost sensor at the back of the engine common fault on 1.9 diesel (its on the air pipe with a plug simlar to the one on the maf sensor)

Using VCDS, carry out live logging. In 3rd gear, log engine measuring block 011. This will log boost pressure, actual vs specified, along with engine RPM and N75 duty cycle, and should give you an idea of what you engine, ECU and turbo are doing. Create a graph in excel or equivalent and post back.

 

Similar to this:

 

 

 

Hi PosterBoy,

 

Did 2 runs tonight and have made some graphs, first run limp mode kicked in early, so I stopped cycled the engine and did a second run. What do you think?

I logged blocks 003 and 010 as well...just for ****s and giggles.

 

Run 2

 

Under-delivering clearly.  Considered a boost leak?

Alternatively the actual vacuum actuator not moving due to leaky diaphragm?

So today was the first chance I have had (due to this lovely weather & work) to check all the pipes and actuator, used a brake bleed hand pump to pull a vac on the actuator and it moves freely like it should. I purchased some 3mm silicon hose to replace the vacuum lines and I am glad I did as look what I found....

 

This was on the hose that runs from the one way valve right down to the N75 - Didn't get chance to put the airbox back together but I am confident I have found the cause of my trouble....a 10p nasty plastic hose.

 

Thanks for all your help.

 

 

Yes - My first thing was going to say a vacuum leak, as I had similar symptoms gradually onset when my hose to the actuator came loose from its bracket and rested on the exhaust manifold - slowly melting.....

 

That should sort it.  Underboost is usually a lot more clear cut / easy to sort, compared to overboost (positive deviation)

Got it all back together today - didn't even bother logging a run on VCDS as she pulls like a train and the MPG is back where it should be.