Sticky wastegate actuator? No boost.
 

Getting a strange issue.
The car seems to boost up fine in second gear, but shift to third and it may as well be normally aspirated.

Could this be a possible sticky wastegate actuator?
Can these be cleaned out?
Anything else I should be looking at?

Pretty stock GC8 + TD04.
No boost controller
Stock ECU

Possibly the wastegate solenoid sticking shut. Google gc8 "check connector" to find how to set up the sensor check mode for your ecu - then see if you can hear the solenoid clicking open. This is a good time to spray it with carby cleaner to remove any internal sludge build up.

plumb it up to just run gate pressure & see if you get same boost in 2nd as 3rd

Cheers guys. Given electrics and I are mutually exclusive items I might just try cleaning some things and if that fails move to the the bypass option.

Could a dodgy AFM have similar symptoms?

I've cleaned out the boost solenoid and check the wastegate actuation. All appears OK, but the boost loss issue remains. Doesn't necessarily appear gear related but possibly related to higher intake air volumes tripping the system out?

how did you check the WG?

Moved the rod in and out. Seems to move OK albeit under spring pressure.

thats not going to tell you much, you should test it with air pressure.

im assuming you didnt plumb the car up to just run gate pressure like i suggested?

have you got a way of measuring boost?

shit aftermarket bov?

Stock BOV.

No, sorry. I haven't bypassed the boost controller yet.
Will drop by to see Doug tonight. May fit a temp boost gauge.