Ibiza Tdi 02 reg ASZ engine.Overboost?

[ESCY]

I am working on this 02 reg Ibiza TDi 6 speed which has the following symptom. During hard acceleration after a few seconds the engine loses power & goes into a limp mode,& remains with lack of power until stopped & restarted.It then has full power until driven hard again.Fault 17965 Charge pressure control positive deviation is recorded each time.It thus appears that there is overboost.
1/The MAF has been renewed.
2/During actuator test the vacuum control unit pulses at the appropriate times.
3/Acctuator test lists a boost pressure solenoid test-could this be the culprit?
3/I understand egr faults can give this symptom?
4/Has it a variable vane turbo & could this be at fault?
Any hints gratefully received!
PS/ I also have an identical scenario on my Sk@!a Octavia TDi-which I have been too busy to investigate!
Regards Andrew Newman.

 

[stoneyfordNI]

yep sticky vanes by the sound of it , mine went off scale a fe times ( +2 bar scary)

i fixed mine by spraying 10K boost straight into the EGR valve, hist 2.0 bar the odd time , but not as much

 

[ESCY]

Hi mate;thanks for coming back so quickly.
Please elaborate-what is 10K boost-some sort of injector cleaner type stuff? How do you access egr valve?
Appreciate the help.
A.

 

[stoneyfordNI]

10k boost is an aerosol , dissolves stuff basically , if u remove the engine cover , there is pipe that runs along the left of the engine then turns righ into a valve (egr) i removed that elbow , youll see the clips , and started the carwhich was already at running temp, then follow the instructiions on the can , i got my can in halfords for 19.99 , n id say it worked , have vagcom data to prove it , somewhere,

just watch because there is diesel and petrol vversions of this stuff

 

[basstard]

no point in swapping the maf and a sticking egr would make you loose pressure, not going too high.

try the 10k or some WD40 onto the actuator arm of the VNT control.
the 10k stays in the cold part of the turbo and goes thru the vanes only when it's been burnt so theorically shouldn't be effective for sticky vanes. Many a person tho told me it freed up the vanes so who knows??

 

[ESCY]

Many thanks fellas;got to be worth a go.
Halfords tomorrow then.
Appreciate your time.
A.

 

[ESCY]

Just a thought- what is this N75 valve I keep hearing about & where does it live?
Cheers.

 

[Neo_VR]

Just a thought- what is this N75 valve I keep hearing about & where does it live?
Cheers.

On the ibiza its the black box on the drivers side suspension turrett..
its the valve that controls the vaynes on the turbo

 

[ESCY]

The box with all the vac pipes to/from it?
A

 

[muddyboots]

Yep. On earlier TDIs there were several separate valves (N75, N18, N239) but on the Mk4 Ibiza they were all combined into the black box on top of the (UK) driver's side suspension turret - yep, the one with all the vac pipes coming out of it.

 

[ESCY]

Many thanks Muddyboots.The mystery is unravelling!
A.