Factory boost controller.

[3500 dually]

I was just wondering how the boost controller actually work. The connector shows having power, is that power coming from pcm? Does the pcm telling it to come on and off? Does the power shut off once it reaches boost. How does the vacuum work in relation to the boost controller? Soory for sounding confuse but just trying to figure out how and what controls the boost controller that is connected on the left side of engine above the valve cover. Any help is appreciated. thanks.

 

[ak diesel driver]

The PCM controls boost via vacuum. The PCM sends a signal the the vacuum solenoid (drivers side valve cover) which varies the vacuum to the turbo and opens and shuts the wastegate.

 

[JMJNet]

Soory for sounding confuse but just trying to figure out how and what controls the boost controller that is connected on the left side of engine above the valve cover. Any help is appreciated. thanks.

Don't be sorry, we are all confused sometimes that is where the FAQ and Technical Library comes in.
Great reading materials in there. I spent around 6 months reading most of them in the other forum which has since transferred here also.

 

[GM Guy]

like explained above, the vaccum is constant, and the little solenoid varies the vaccum to the wastegate controller, which operates the wastegate.

If you are after fuel economy, the OEM vaccum system is the best without upgrading to a big housing turbo.

If you know how the system operates, and how to diagnose any issues, the vac system really isnt that bad. I personally rely on it and trust it, and I routinely make 1,000 mile jaunts with the pickups across Wyoming to Idaho.

 

[schiker]

Like others said the PCM commands the vacuum solenoid. The vac pump will build a constant vacuum and the PCM will waste away excess vacuum to the vacuum actuator at the turbo via the solenoid to allow the waste gate to open. Opening the waste gate wastes away drive flow of the turbine which takes away compressor speed thus boost.

The PCM has a boost map for rpm and fuel rate (and a few other inputs). It's pretty conservative. And can command for limited boost when you could use a bit more. The map is not open or close on the waste gate the is a little logic. It has a neat low boost when the engine is in cruise light fuel rate around 2000 rpm +/-. It also has some safeties with high intake temperature. The system can be tweaked. Only real drawback is more possibilities to fail and the spring systems are basic/simple and usually more reliable.

You probably can find more details in tech library.

 

[schiker]

Like others said the PCM commands the vacuum solenoid. The vac pump will build a constant vacuum and the PCM will waste away excess vacuum to the vacuum actuator at the turbo via the solenoid to allow the waste gate to open. y.

Maybe that is not the best way to say it. PCM will command vacuum solenoid to modulate so that the vacuum actuator sees Y vacuum while the pump is still pumping X vacuum. Y being the a prescribed vacuum force for the waste gate vacuum actuator according to the boost map programmed. The PCM does not necessarily read intake boost and react. I think it has a set command map and as long as the boost is in a tolerance range (knowing rpm and fuelrate) the PCM is happy. If boost goes out of tolerance it will code.