sundera86

before 1 month i drove my cossy 4x4 and boost pressure was 1,2bar overboost and 1 bar in high rpm !
today i drove the car and the boost pressure drops from 1,2 bar to 0,8 bar in high rpm ?
please help

martynhomer01

iTrader: (1)

could just be an inacuracy in the guage mate?

sundera86

i dont think so, the car is slower, i drive without amal valve, i am with manual boost controler, should i fix the problem with bleed some air from boost controler?

sundera86

how can i understand that my actuator work properly. Some test for actuator ?

NEILNATO

sounds like a classic weak actuator to me, or maybe a leak in the vac hoses connecting to the actuator, try looking at the latter 1st before you condemn the actuator

sundera86

if my actuator is bad i think that peak pressure should drop also. Why my pressure drops dramaticly in high rpms? My peak pressure is ok - 1,3 bar but in high rpms it drop to 1 bar sometimes to 0,9 bar. Is it possible actuator go wrong only in high rpm

NEILNATO

basically at high boost if you have a weak actuator spring the force of the boost will push the rod out alot quicker resulting in the wategate opening too early at high revs, but will stay closed longer lower down the rev range which will make the issues you are describing, another possible cause which i have came across in the past was the cam timeing was out so at high revs and as it was quite a fierce cam and it was keeping the exhaust valves open for too long hence loss in power, this was on an rs turbo which only has one camshaft but im sure the same would happen on the twincam YB. just a thought

sundera86

is it possible the problem is dump valve ?
how can a check dump valve ?

ST Turbo

Take the dump valve out completely, and see if it still drops off and loses boost. But is most likely to be the actuator as everyone is saying!

sundera86

ok it is maybe actuator, but why when i bleed some air from boost conntrol peak pressure gains perfect and in high rpms there is dramatic boost drop.
I think if the problem is actuator it should be problems with peak pressure also ! Am i right ?