hi i got a m99 uk with a power flow from cat back , hks dv, boost gauge,my problem is as follows i have had boost prob for a long time the car will not boost over 8psi i have cleaned the boost sol, pipes, checked for leeks reset ecu still no go . i then put on a man boost controller from my gt4 just to see if i could get more boost i did but as soon as i hit 14psi it drops back of to 8psi again like i have lifted of the pedal a bit this is the same every gear not fuel cut its a smooth drop any help as i am stumped now cheers

 

Have you replaced any of the little pipes with the t piece going to the actuator/turbo/boost sol as there is a tiny little restrictor if this is missing you will only run around that boost mine did anyway. If not could be actuator .

 

very good point the pipes are all new as the engine was rebuilt but i dont think it has restrictor in but i will check cheers

 

It diffo will have one if i remember right if its stiil subaru pipe work its marked where the restritor is with a red dot you can also feel it as the pipe swells slightly its one of the coming off the t piece it it has no restrictor this is your prob its there to acheive about 0.9 bar of boost on your model.

 

i had a look this morn and yes you are right all my pipes are blue after market ones with no restritor in the pipe work i will get some proper subaru ones with the restritor in and report back thanks for your help

 

What type of manual boost control did you fit and where? I have a dawes fitted between the turbo output and the actuator, no restrictor is required with this setup.

It could be a weak actuator spring, the manual device may not have cracked open until 14 PSI, then the exhaust gasses could have pushed the wastegate open giving you the same 8 PSI you had before.

Can you easily check the actuator by moving the wastegate arm, see if it's loose?

Just a thought.

 

it is like a dawes i dont want to keep it i was just checking to see if i could get more boost which i can but it hits 15psi then drops to 8psi bummer i think it is the actuator as well can been the only thing left really any way cheers mate will keep you posted

 

i had similiar problems ir could be ur ecu u might be getting overboost causeing the engine to restrict the boost pressure try another ecu if u can

 

i might be wrong !!! but i put a bolt in the end of pipe that go to the boost control sol when i had the manual boost controller on. if this is the case the ecu would have no control over the boost which leaves me to think? it could be the wastegate actuator playin up but i could be wrong cheers 95blackwrx

 

You would know if it was overboost as it is a complete fuel cut. with a manual device fitted the ecu has no control anyway.

Another angle could be the dump valve opening, have you got the original unit? throw it back on and see.

 

no got the car with the hks one took it to bits give it a good clean all was ok well i hope ?????????

 

you was spot on cheers i made my own one went to the old mans workshop found a 1.2mm drill bit then found a nice hard bit plastic and away i went scooby flys again