My mates 98 WRX is not making much boost, the best we’ve seen is around 0.5bar, and this comes in around 4000rpm, with any slight lifting off the throttle boost drops quickly. This fault has been with the car since he bought it, so lack of history makes problem worse.

We’ve changed the dumpvalve back to standard ( from my car, it’s good)
Cleaned/ later swapped in another, boost solenoid.
Changed the MAF
Did ecu resets each time, same result, slow building boost, which is hard to maintain.

Did a brief (dodgy) run with the pipe to the WG actuator removed and clamped, still 0.5 max.

.
I’m thinking boost leak, but can’t see any.
Exhaust is tight and not blowing.

leaky wastegate?, or knacker turbo.

Car is not giving a CEL

I can here an unusual sound when the engine is turned off, like turbo slowing (sound like plane engine shutting down)..

Anything else I can check before looking at the turbo?

thanks

 

Sounds like the wastegate has a problem if its only boosting that high, if you take the downpipe off the turbo and shine a light in you would see the problem if the gate is not shut or is cracked.
As for the noise..my IHI VF28 makes this noise when switching off, because its a roller bearing turbo it runs on for quite a while after switching the car off..a bit like a washing machine, but without the suds. LOL.

 

ok i dont know much about turbos and stuff on a scooby but is the boost not set?? meaning it should only boost to a set limit?? doesnt this have to be changed if you want it boosting higher?? for example when i had my rs turbo..in order for it to boost a bar you had to wind it up from the turbo (sorry dont know the tech term) lol are scoobys not the same sort of thing? mine boosts 0.5 bar till it hits 5k on the revs then boosts a bar

 

Have you cleaned/checked the boost solenoid

Rob

 

Did a brief (dodgy) run with the pipe to the WG actuator removed and clamped, still 0.5 max.




This would rule out the solenoid...

 

yup, did a quick run with the actuator pipe removed and clamped, (to ensure a closed wastegate) , while closely watching the boost gauge, and still 0.5bar.

Correct me if I'm wrong, but this rules out ALL ecu control of boost, MAP sensor, boost solenoid etc, as It's pure mechanics??

My mate is dropping the downpipe for a nosy at the wastegate, turbo exhaust wheel