Thread: Disco td5 overboosting?

Your findings are consistent with a sticky modulator. If it has stuck completely then you can test it (with ign off). By default it should allow full airflow from the turbo outlet pressure line direct to the wastegate actuator but when its stuck in the unmodulated position, you cannot blow through, or if partially stuck you can blow through to the turbo inlet pressure line.
They are quite inexpensive.

Edit. It can be bypassed by connecting the turbo outlet pressure line direct to the wastegate actuator to prove the fault on the road.

A little light libricating oil and a good working with a spanner or similar on the linkage can free it up and fix the problem. Did mine a while ago and just done a friends 300 TDi with the same issues.

Thanks for your answers.
Urban Panzer,your site is kind of an inspiration for the "DIY selfers" Disco owners - keep going.
Graeme i thought of bypassing the modulator,you confirmed-l'll do it!
Just for the record the full description of the faults is:
03-05 driver demand problem 1 current
and
20-02 turbocharger overboosting logged.
I pushed the linkage with a long screwdriver,it moved - albeit with large resistance from wastegate actuator i guess.
Couldn't get the turbo heatshield off,the nut(or bolt) sideways of the turbo,just won't move - i wanted to remove the actuator in order to work the wastegate lever full travel by hand.
Question to nanocom owners,when wastegate starts to open,should the manifold pressure reading drop immediately to 100Kpa(or ambient pressure) or drop gradually?
Thanks.

Originally Posted by fatman

Graeme i thought of bypassing the modulator,you confirmed-l'll do it!

I carry a length of tube for this purpose. Much better to have reduced power than fuel cut-out.

Just changed the wastegate modulator,32 euros and problems solved.
Thanks fellow members and thanks nanocom!