sundera86

i have sierra cosworth 4x4 stage 3 with garrett t34 and original t34 actuator, i drive without original amal valve, i have boost controler which is closed.
Cars runs okl at 1,2 bar peak and 1 bar held pressure. But today without any reason turbo pressure drops from 1,2 bar to 0,8 bar at high rpm
please help because here in bulgaria there is no cossy specialist

rich123

iTrader: (3)

maybe a week actuator try putting a -31 actuator on it

sundera86

m8 i drove with this actuator since 1 year and i have no problems. Today pressure drops to 0,8 bar in high rpm, this not happend never before

Jim Galbally

sundera, actuators can wear out you know, especially when running significantly higher boost than they are designed for.

could also be a leak in your inlet system, a big change in ambient pressure, a fucked turbo, loads of things

sundera86

how can understand if my turbo is fucked? at intercooler there is no motor oil

pee vee

the Spring in the actuator! not the turbo itself

try a new actuator, is what they are sayin!

sundera86

is it possible to fix the problem if i bleed air from boost controler

Jim Galbally

no, just replace the actuator with a -31 which is what you should really have been using for those boost pressures in the first place.

Rax

iTrader: (1)

Dont turn the boost up,change the actuator or spring.Mine did the same,it was running a -34 and went limp so I got a brand new one,a -31 didnt check first.Luckily the new one is a alloy one so I just changed the spring back and lowered the boost.Ta daa 24psi flash and all was good.

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

Jim Galbally

yes, infact its the most common failure

sundera86

could i open the actuator and replace the spring inside the actuator

Jim Galbally

no, they are sealed units.

http://www.cosworthpartsonline.co.uk/

brand new -31 for 70quid from motorsport-developments

Rax

iTrader: (1)

Alternatively use one of these as you can rebuild them if needed.

http://www.mongooseexhausts.com/mong...-Actuators.htm

Gary F

iTrader: (1)

It'll be your actuator mate, or a boost leak.

Andreas

Since he is not using a amal valve I wouldnt buy a -31 as its base pressure is lower and wont be able to produce the same boost as a -34 without bleeding. If you are getting a new actuatar, get another -34. Atleast that is my suggestion but you might as well ask Motorsport Developments for advice before purchase.

Gary F

iTrader: (1)

I'd also stick with an amal valve...

Jim Galbally

thought he was using a std one?

markk

iTrader: (2)

its more likely that at the higher RPM's the engine has become more efficiant and has consumed what you have given it, (VE is more likley whats improving on you engine at higher rpm)

pee vee

what would cause an engine thats been set up etc. suddenly start being more efficient? Or am i mis-interpreting what you are saying lol.

Rax

iTrader: (1)

Ignore my post I miss read.
I use amal valve on mine.
I really don't see whats wrong with the original setup unless you are mega boost

sundera86

is it normal my boost pressure to be lower at 1st an second gear?
at second gear i have peak pressure 1,4 bar and in high rpm drop to 1,1 bar
could you tell me what is your pressure at different gears
my is
1st 1,3 peak - 1 bar hold
2 - 1,4peak - 1,1 hold
3 - 1,5peak - 1,2 hold
4 - same
5 - same

markk

iTrader: (2)

maybe I misunderstood it slightly, has it before been holding the boost, then all of a sudden stopped holding it?

is the engine a new build ? has the ambient temps changed dramtically one way or another?

pee vee

yes. lol pretty sure it is