Flaps? What flaps?
AO Silver Member
Join Date: Oct 2014
Location: United Kingdom
Does it come in at higher revs?
I believe this is usually either sticky VNT veins (within the turbo), or leaks on the VNT vacuum hoses/actuator outside.. At high revs the veins on the exhaust turbine redirect the exhaust gas to bypass through the turbine rather than spinning it, thus creating lower boost...
If the veins are sticking, they won't move properly and you get overboost at the top range of the revs... If there's faults in the vacuum actuation system, the veins don't move properly and you get overboost again..
Worth checking over all the vac hoses for splits/cracks etc., very cheap fix if this is what's wrong!