I was thinking the other day and a question came up, how does our stock boost drop at 3500...

I mean really thinkabout how wastegates work, our turbo and wastegate are T together so wouldn't that mean that the wastegate will open at whatever it is set to open at. How can the stock solinoid regulate boost if the wastegate is tied directly to the turbo unless the turbo's wastegate is set to open at 19psi and after 3500 the stock solinoid leeks off boost after 3500 and the wastegate never opens. Thats the only logical way it could regulate boost based on it's design. If this was true then a simple boost controller could consist of simplely a rubber tube jumper going from the turbo to the wastegate and bypassing the stock boost solinoid.

What do you think....

 

hmmmm, i wanna know too

 

The explanation I got from another thread is that the wastegate is actually set around 11psi. The solenoid has two positions each calibrated to bleed a certain amount of air off before it reaches the wastegate actuator. So.. until the ecu see's a certain set of circumstances the solenoid is in the position that bleeds more air hence givign you 19psi or so then it flips to the other position bleeding less air and dropping the boost to around 16psi.

 

I understand how solonoids work on boost, my question is the turbo outlet is directly T'ed into the wastegate.... so the wastegate will see whatever is outputted by the turbo.

Just to confirm, the wastegate is set at around 10.5-11 my boost controller off reades around 11

P.S. Stock solonoid must be left plugged in or you will throw a code.

 

Well, If I understand you correctly... The solenoid must be in line between the turbo and the waste gate otherwise the wastegate would open at a turbo outlet pressure of 11psi right?

There is a vacume diagram on techinfo.... If I can find it.

So to answer the question, yes you probably could bypass the solenoid and run a line from the turbo outlet to the watesgate inlet as a form of boost control but you would be limited to 11psi unless you find a way to bleed a calibrated amount of pressure... which is what a boost controller does.

 

yes i understand all of that already... my question is if the turbo outlet is tied to the wastegate and the boost solonoid at the same time, that would be both the boost solonoid and the wastegate see the same psi. If this is true then the solonoid can't regulate it becasue it equally reads what the wastegate reads at the same time. If the solonoid was before the wastegate it would be easy to explain

 

It functions by pressure against the wastegate actuator.. if it was tied directly (Plugged off the hose to the solenoid) it will open the wastegate at whatever spring pressure it has.. By bleeding off small mounts of air (from the T to the Solenoid) it will require more air pressure to operate the actuator (because some of the air is lost through the solenoid)

Basically all that means is that there would have to be more pressure (more boost) to open the actuator.. The actuator still opens at 11psi, but 9 or so PSI is bled off by the solenoid..

 

ahhhhhhhhhh that makes sense, thank you.

 

Electronic solenoids don't have "2 positions". They operate in cycles/oscillations per second similar to the pulses/second of a fuel injector. The ECU simply adjusts this duty cycle to achieve desired boost (release air pressure from the wastegate actuator or increase pressure on it).

VV

 

There is some speculation that the solenoid is only a dual position "Valve" which is either open or closed.. Although your assumption about the solenoid an duty cycle is correct.. I haven't seen a definitive answer about how the solenoid is operated.

 

ah it's opperation is of little importance.... it's ports are disconnected