i have a s5 13bt with a n371 redom ecu but i havent been boosting like i was when i first installed the engine (12psi now only boosting 5 psi ) i have tested a few things and found the turbo duty solenoid is not working properly can anyone explain to me what the solenoid exactly does and what i can install with my ecu to get back to the 12psi or possibly higher

 

If it was using the stock solenoid to control boost, it's what controls the wastegate to allow you to boost to whatever the ECU was programmed for. If it failed in a state that allowed air through constantly, it'd only boost to the wastegate spring setting which is likely what you're seeing now. You can either replace the solenoid or get an aftermarket boost controller.

 

Check to be certain the wastegate rod attached to the flapper. The C clip at times will fall off and no boost over 5. As far as the solenoid, it bleeds air from the system and literally works itself to death trying to get the boost up. You can check the solenoid with an ohm meter, but best to disconnect and add a boost controller, at least that's what I did on the '89TII.

 

thanks for your help any opinions on what kind/brand boost contoller to get and is a mbc better or worse than an ebc

 

is it only the s5's that have this solenoid not s4's?

 

not sure ive only owned s5 models

 

Only S5

Look at the Hallman MBC. You can even get a remote cable to change it from inside if you want.

 

EBC's tend to have better response, as they're less likely to 'bleed' air to the wastegate early. They also come with usually a high price tag. If you can flip the bill, go electric.

 

How do you know the factory EBC has failed? When you apply +12V to it, does air pass through it? I would check the aforementioned c-clip.

most factory boost control solenoids are capped at 95% duty to prevent overheating. I know the FD's two boost control solenoids are. I'm skeptical that there is no cap.

 

the c clip on the wastegate rod is still attached