Boost Solenoid Operation?

[kaldek]

So with all the hype around this magical power-recovery by cleaning the boost solenoid, I just have to ask some questions.

First up, what does the boost solenoid DO? I mean, if the turbo spins, it creates boost - surely the solenoid is used to LIMIT boost, applying vacuum to the wastegate, yes? Oddly it doesn't look like your average vacuum hose...so I could be completely confused.

If I'm right though, what on earth can cleaning the solenoid do aside from make the wastegate open quicker when max boost is achieved? And how does that help power?!

Someone...anyone?

Edited 28/05/08 03:21 AM by kaldek

[senna_T]

The solenoid is a boost controller in simple terms. It controls when and how much the wastegate actuator opens. If the solenoid is sticky it will not open as quickly or early as it should

[Fat-Tony]

It doesn't. Mine has never been done, and I don't suffer from delayed boost.

I might go do some before and after logging on the boost control and play Mythbuster.

[senna_T]

in my experience I have had a couple of instances when the turbo seems to kick in later in the rev-range - this isn't dependant on heat, it happens any time - and when I cleaned the solenoid it was all good for a few months

[sargo]

Will be interesting to see what Fatsex comes up with, there was a natable difference in my car's performance after lubricating my boost solenoid.

Anyone else get this result?

[sargo]

Did I say natable?

WTF

I meant notable..

[kaldek]

The solenoid is a boost controller in simple terms. It controls when and how much the wastegate actuator opens. If the solenoid is sticky it will not open as quickly or early as it should

Right, so wouldn't that mean that if it's sticking you're getting MORE boost?

As I understand it, the ECU has the ability to cut fuel and/or ignition to the engine if you're getting too much boost (I.e. the wastegate has failed).

If what you say is true, and that cleaning the boost solenoid "increases power", then the only conclusions I can come to are thus:

• A sticking boost solenoid is causing overboosting
  
• The ECU is detecting the overboosting and reacting by limiting fuel to the engine
  
• Limiting fuel to the engine is much more aggressive than using the wastegate
  
• This in turn results in a feeling of lost power
  
• Cleaning the boost solenoid allows for a more *accurate* control of boost, which in turn feels like "more power"
  
• The ECU should probably report error codes if fuel-cut intervention is required to limit boost!
  

I'm happy for someone to come here and correct me!!!

[dule]

Maybe it keeps the waste gate partially open when it gets sticky.

[sargo]

Here's a wild and crazy idea Kaldek, invest 10 minutes, go out and lube your boost solenoid, go for a drive and let us know what you think.....

[senna_T]

^^^ that's an idea

its not so much about getting more power, its about the response, if the solenoid doesn't get the actuator to close at the right rate, it will let more exhaust gas bypass the turbo, hence less boost at lower rpms