Boost Solenoid problems MY93 WRX
 

Can someone explain where the Boost solenoid gets its power from and is it the ecu that is sending the signal to make it click?

Reason I ask is because I’m getting very erratic boost, sometimes I get full boost other times I only get 5/6 psi. If I join the green connectors for test mode the solenoid clicks away like mad but when the engine is running it doesn’t click. I’m sure I read it only clicks above 2000rpm but mine doesn’t. When I have full boost though I think I can hear it above the noise of the engine/exhaust.

So the 2 questions I need answered are, what is controlling the electricity that makes the solenoid click? And the second is I assume that the problem is with the device that makes the solenoid click rather than with the solenoid because it works in test mode.

Thanks in advance for your help

The solenoid is driven directly from the ECU.

How much boost are you seeing (full boost) ??

When I was using the std boost control I couldn't hear the solenoid 'cycling' when the turbo was boosting.
Try removing pipes to the boost solenoid (labelling where each goes), connecting the test mode plugs - then spray brake cleaner into the ports to clean the solenoid whilst in test mode ;)
Also check to make sure pipework to map sensor/pressure exchange valve/actuator is intact and not damaged. It is unlikely that the ECU is at fault tbh.

Cheers :D

on full boost i see about 10/11 psi which is right i think.

The car wouldn't start recently and the garage did find a problem with the ecu, someone had cut into one of the wires and had left it shorting against the bodywork. he thought it had been connected to some kind on monitoring tool at some point which was probably taken of when it was imported.

if thats been shorting for a while the ecu maybe damaged.

i cleaned the boost solenoid and even bought a second hand but still have the same problem which is why i'm thinking i have a ecu problem but how do it test it without buying a new ecu?

My MY97WRX has this same problem, I have been cleaning the boost solenoid and associated pipework out, checking for splits/leaks to try to resolve the error. I get .5/.6 bar when faulty and 1.2 bar when ok. I have a scoobymonitor built and installed and can see the Boost Controllers duty cycle on full boost go from 50% to 0% when the problem comes back. I dont have a knocklink yet, but will have soon to check to see if it is a genuine limp home mode ecu adjustement, even though the scoobymonitor doesnt show any knock correction. Its very frusttrating when it happens though. The only thing I cant check is like you the ECU.

does anyone know where to get a secondhand ECU for a MY93 WRX, think it will be a W6 one.

does anyone know if a Z4 ECU will work with a MY93 WRX, Its a W6 thats in at the moment?

yes, the Z4 will fit and will give you a performance improvement too.

if all else fails use a manual boost controller like a GBE boost valve or a dawes device.

cheers, will bid for it now.