gtt feels weird on boost

[matty_j24]

hey guys i just bought a gtt caldina its stock standard bar from a blow off valve and a pod filter when it initially comes on boost it feels like it has heaps of power and i can hear the turbo spool just over 2500 rpm then it dies down for say 1000rpm and the car seems to get another kick at about 4000 rpm is this normal on a caldina im going to get a boost gauge to make sure its not dropping down maybe a leaking blow off valve? any info from any1 else with a standard caldina would be good o yeah its a manual if that makes any diff?

[flygt4]

its not normal.
could possibly be a leaking wastegate diaphragm or a split actuator hose or a leaking bov , or a leak somewhere.
they are also known for cracking/warping exhaust manifold/turbine housings even in standard form. if you remove the heatshield over the exhaust manifold they often crack in the top lefthand corner where it looks like a bolt should be but isnt.

santas_boosting_sleigh had a similar thing with his gtt, and it had similar surging boost symptoms. after removing the wastegate it turned out to be a leaky diaphragm.
be careful, i wouldnt go around with your foot flat as you may overspin the turbo and damage it.

id install a boost gauge , and watch the psi when it comes onto boost, you may find its spiking to a high boost pressure then tapering back or something silly.

[matty_j24]

hey took off the cover no cracks in the manifold found a kink in the vaccume line running to the valve and also took the valve off to inspect it i shook it and it made a rattling noise an i blew on the inlet side of the valve and air comes out the seals r f***ed ill put on a new valve and let you know

[matty_j24]

hey just replaced the bov it goes heaps better now but it a few times it stuck on about 4000rpm on the gauge and then just jumped up to 5000 it has never done this before i will be getting a boost gauge in the next two days to check the boost too

it has a pod filter fitted and i saw a sensor which would usually go in the factory air box just sitting in the engine bay would this affect it?

[flygt4]

good to hear changing the bov helped it. cant say what would cause the other problem tho

[Santa'sBoostinSleigh]

the boost does spike up to about 14, then taper to ~11
this was covered ages ago and is some factory bullshit thing
dont boost over 15PSI whatever you do
and i hope you are running high octane fuel

[matty_j24]

im running it on 96 i get my boost gauge tommorow so ill see what is happening im not gonna run over 15psi and wont put it up to that till i can get my new turbo and ecu etc etc

[Santa'sBoostinSleigh]

run it on the highest octane that is available
if you can get 98 and you dont use it because 'its more expensive' you dont deserve a turbo/performance car (in my opinion)


until you know what boost levels you are running dont plant your foot
if there is a problem and you are overboosting, its going to cause pain at some stage

pics of your car, under bonnet may be of help

[matty_j24]

most places sell 96 round where i live so i just chuck 96 in it will post up on the weekend what it is boosting and let you know if its holding boost properly it feels alot better and isnt cutting or anything dont 3sgte's have a cut at 12psi?

[flygt4]

no, the caldina 3s will run up to 14psi standard. santa's spiked up to 20psi with no cut when it had a leaking diaphram. if by better you mean faster that may even be a bad thing

[matty_j24]

by better i mean an even pull a little bit quicker but that is because the valve i could put my mouth over the inlet and breathe it was really $&#$% im 99% sure its running how it should now we will wait and see what the boost gauge says tho made sure i got a good accurate one too, i took off the heat shield and the actuator moves freely its not siezed or anything no splits in the actuator line no vaccum leaks no cracks on the exhaust manifold etc