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Hi all.

A quick run down, Ive had my gtr for about 5 years and anout four years ago i put a pfc on it and pulled the restrictor out. All good abot 14 psi. I dont drive it all that much but earlier this year one of the ceramic wheels came off and filled 4,5 and 6 with bits giving it a on road hone job. I fitted a 2nd hand engine wih new Hks GTSS turbos and put the restrictor back in until i had time for a proper tune. Over the last couple of days ive had it on the dyno and we had some minor issues with the software and yesterday it was running actuator pressure (about 10 psi) we sorted that and today it was running about 12 with the restrictor in so i pulled it and the boost went up to 15 or16 which is what i thought would happen we did a couple of runs and touched up a bit of fuel and then on the next run it touched 15 and then levelled out back at the 12 it was running with it in.

It continuied to do this so we stopped tuning.

We looked all over for boost leaks but couldnt find any and it seems strange to me that it is exactly back to where it was with it in.

Any one got any ideas?

I know people will say just put on a ebc but why when all i want to run is 15 or 16 and if the factory one does this then why replace. Obviously if i cant get it sorted i will have to but it was perfect for 2 full power runs.

Thanks

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no i used the new hks ones and tested them for opening pressure and they were both fully open by about 11 psi which gives me the option of running very close to stock boost if i ever want to. This is what it ran when i disconnected the boost control solenoid when we were playing around looking for a issue.

I had my blow off valves off today and had a good look around the valves and the hoses down there but they tested perfect and everything looked good.

I will keep on looking but im thinking i might borrow a cheap boost controller off a mate and see if ican wind it up to 15 and if it holds then it is a problem with the standard boost control and if i cant get it up then its a mechanical fault like a split hose that only opens under higher pressure.

Could be a blown inlet or any of the 3 tb gaskets as they are paper and easily crack/burst due to age and that burst of 15-16 psi of pressure. Give them a good spraying with aerostart or something similar around the gaskets, should be able to pick up an inlet leak easily enough as the revs react and climb

Might be a good opportunity to put some metal gaskets in if it (probably a good idea anyway if putting 15-16psi into the inlet manifold anyway, as I don't think the paper ones could take that pressure over time anyway)

I know you said there were no leaks but can you be absolutely sure? What about the intake, is it possible for it to partially suck shut, could the cat have collapsed? Possible to adjust the actuator rod and see what happens?

All of the above could cause this issue.

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