Positive Deviation (overboost) 17965

[Chrispb]

Well it's finally happened after 7 years of me driving our Mk2 with no problems and now passing her over to my daughter since the arrival of the new Mk3 the dreaded overboost has shown it's ugly head, coincidently after a new EGR valve fitted.

I blame her for her mega stop/start short journeys

Will start with manifold cleaning and possible turbo strip down hopefully it comes apart without bolts shearing off (doubtful)  now on 118000 mls
Will keep updated on the progress.

[Mirez]

Bugger! It might just need a bit of a work out?

Take some photos if you strip the turbo down will ya?

[Chrispb]

Yes of course.

[Chrispb]

Update
Had the intake manifold off first, a 1 to 2mm layer of sticky soot adjacent to the EGR flange, the cylinder head end more oily and less soot so no real problem there.
Next removed turbo to check vanes, ground down a 17mm spanner to hold the oil supply pipe union from turning while undoing the pipe, dismantling the turbo all fixing bolts came undone without shearing off
A light coating of dusty soot, most of which blew out with airline, again not the problem but glad I done it anyway.
Waiting for new gaskets now and will clean all the other bits tomorrow.
Have taken a few photo's of the turbo vanes removed, will post up later.
Will also be checking Cat for blockage as it's still the original.

[Chrispb]

Further Update

Rigged up a temporary canopy to keep the rain off, then refitted turbo and inlet manifold, removed cat and front pipe, although pretty corroded on the outside the honeycomb looks good so have refitted.
Will give a good road test tomorrow with vagcom hooked up.

[Mirez]

So not the cat, turbo or intake? Faulty actuator and/or N95 is all that's left isn't it?

[Chrispb]

Well after all that hard work with removing manifold and turbo, cleaning off all the soot which was nothing compared with the photo's of your's Mark.
Have run the car today with vagcom no faults collected and the log looks OK to me which have uploaded here, could you convert  the relevant part to a graph as I don't know how you did that

[Mirez]

Looks ok, there are some deviations though - most evident in section2. The logs so big though I couldn't graph it all as I didn't have the time so I've done random sections from the parts...

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[Chrispb]

Cheers for that Mark am back to work today but will do the pics asap