I couldn't find a thread on this, and I thought it might be good to show what I have found.

My car is a 1997 Preg V3 Sti Wrx. It's been decatted with a monster bellmouth down pipe and straight through centre pipe. It's had the headers ported aswell. It runs a standard IHI VF23 with a silicon intake and k&n intake pipe.

Basically my car wasn't boosting in a very refined fashion, occasionally overboosting or hesitating, and hesitating in higher revs occasionally.

So I took the advice I found and simply cleaned it with brake cleaner. This simply made it run a little better, until the next day when it was dumping basically all the boost.

Before I started all this messing about I could never hear the solenoid clicking in test mode, i.e. Connecting the greens and Turing ignition to on (NOT STARTING THE CAR). After cleaning with brake cleaner it clicked, but today after having the no boost problem it didn't click, in my opinion it's stuck.

So the steps I took:

*NOTE* Don't start the car with any of the dash connectors together unless you know what your doing.

Unbolted solenoid, but left the round connector plugged in. This is so it's easier to play about with. I then connected the green connectors, and turned the ignition on. So instead of clicking, it was just partially open in my opinion.

I then sprayed some degreaser in and then tapped it until it began clicking again. Then I turned ignition off.

Now I sprayed some SAS spray in, it's just like wd40.

Turned ignition on again with the green connectors together. As it clicked I sprayed the SAS in again.

At this stage I was happy that the solenoid was working properly.

So I put it all together and took it for a spin, after unplugging the greens.

Straight away the car felt so much more refined. Boost smoothly and strongly. No hesitation or overboosting.

I hope this can help someone, it's to show my problem and how I seem to have overcome it.

 

personally, if your boost soleniod was stuck, then i would replace it as not to have any further issues in the future. surely you have to look at it as if it siezed up, what caused it? instead of masking the problem you could have a look at sorting it!

 

Accumulation of oil blowby over time is what causes the boost solenoid to get stuck. If you've had a look at the intercooler, you can see how much oil collects in there.

I think cleaning it is therefore justified as opposed to replacing it.

 

Yea, carbon filled oil particles make there way up the pipe to the solenoid, and just builds up in it. I don't now what it looks like on the inside. But most people know how a solenoid works! It's just a shaft that pushed side to side by changing direction of current in a coil. So yes I totally agree that cleaning it is fine. Plus where would you find a new boost solenoid for an old impreza, other than upgrading it to a three port. Any used one that I could have bought may have had the same problem.

 

my comments are of my own opinion! i cant say i have ever seen one 'stuck'. i have seen oily deposits and oil filled soleniods. my basis for my comments are if you had a progessive build up of oil deposit in the boost solenoid surely you would of seen via a boost gauge or felt a lack of power and issues with the boost over a period of time. in the OP you said it worked you cleaned it then it stuck, to me in my opinion i think you will have an issue in the future with it again so i would be looking to change it!!