Ive just fitted a reconditioned PD150 turbo to my vrs, however its having issues with overboost. On the standard pd130 map it is overboosting slightly, peaking at 1.65 bar then coming down again slowly. The N75 is showing 79% at 4000rpm which i believe is correct. There is no lag it kicks in when it should so i would have thought the stop screw would have been set correctly.

When my mapper puts the revised map on it for the bigger turbo it just spikes in overboost to 2 bar. he has adjusted the map and reduced boost etc but it still wont hit the target boost until gone 3k rpm. Ive uploaded a graph to show the issue with the standard pd130 map on the car.

Ive checked the actuator moves freely and holds a good vacuum when tested. No faults logged in vcds

Anyone have any suggestions?

 

Had similar problems when refitting a standard turbo on my car recently cars been mapped. Tried adjusting the actuator length and stop to all the figures I could find on here but couldn’t get it right going of those.

 

In the end the problem was the actuator rod length. On the standard kkk turbo I lengthened the rod to stop the overboost, adjusted it till it matches the specified boost then you should be good to go. Not sure if you have to shorten or lengthen the rod on the pd150 as I think the Garrett turbos work in the opposite the direction to the kkk ones due to the vacuum being applied to the opposite side of the diaphragm on the actuator.

I could be wrong on that though.

 

I’d suggest adjusting the rod length. A couple of turns then go out and log it and see how it’s changed. If it’s made it overboost more wind it back in the opposite direction, if it stops the overboost then adjust it Until the requested boost and actual are pretty much the same. It probably only needs one or two turns either way to get it right. HTH 

I managed to resolve this , was a dodgy MAP sensor in the end should have updated it