159 2,4 JTDm Q-Tronic loses pressure
I had agreed to buy a 2,4 JTDm Q-Tronic which I should pick up this evening. The test drive went along ok (I think that when driving "on-off" at low speeds the gearbox is a bit jittery, though) but suddenly the following happened:
I used the manual shift mode, placed the car in 4th gear and decellerated to about 1,600 RPM. Then I floored it gently and as soon as it had built up full boost at around 2,200 RPM it lost all the turbo boost and started building it up again. It went from app. 1,4/5 in boost to 0,4-5 or something like that and then built up boost again. It didn't happen in 3rd gear but was even more apparent in 5th, whereas in 6th it happened over and over again.
Is it a normal feature to spare the gearbox or is there a fault on the turbo, wastegate or something else?