How do 3rd gen wastegates work exactly?
 

i have a 2004.5 which i believe is electronic wastegate. having said that i noticed it still has a mechanical actuator that opens it. the ? is , is the actuator controlled by vacuum or by air pressure? Where does it get the psi/vacuum? does it get it from that motor on the turbo or does it get it from excess boost? does excess boost go through that electronic motor on the turbo or is that mor elike a electronic orfice?

is the excess turbo air bypassed through a port and fed into the wasyegate actuator and makes it push? or does the actuator pull?

The electric motor as you refer to it is basically a sensor that feeds the ecm with a electronic signal.. It tells the ecm what boost psi the actuator is receiving .The boost air pressure actuates the diaphragm that extends the rod opening into the gate valve of the exhaust housing bypassing compressor pressure. So it pushes the rod which opens the valve Does this answer your question? A little boring stuff but higher psi boost pressure doesn't equal more oxygen to burn the fuel. You can crank and fool the ecm into supplying More fuel but it does not burn because higher psi just makes the temperature higher and air expands with less oxygen. The exhaust housing ultimately dictates how much pressure exits the engine. The stock housing is 9 cm which equals a 1.3" id pipe. In a nut shell hot air in hot air out!Don't be fooled thinking more air pressure is the end and be all. There is a thing called volume/heat simply ratio. It is called effiecentcy............ In a nut shell more boost psi doesn't mean more oxygen to burn the fuel, just higher exhaust temps! This is why we all must go to a after market turbo to address the high temps caused by the restrictive turbo exhaust wheel/housing.

I don't think it works like that on the '04.5+ turbos. I believe the electric motor is just that...it opens and closes the WG. The ECM sends a signal to that motor to tell it when to open and close the WG.

The older turbos and aftermarket turbos use a mechanical WG which is operated by boost pressure pushing a diaphragm inside the actuator.

jrrussel i think your more right as there is a PWM signal to that motor. it is measured in duty cycles.i just dont know if its making vacuum or air pressure or creating a orifice?

It moves a rod that opens the WG port.

ok so when it opens wastegate port its allowing air to the wastegate actuator?

when the wastegate opens it allows the exhaust gas bypass the turbine wheel

Sallyman, read my post in 67 pounds per minute. I get into great detail about the 04.5+ wastegate.

And to quickly answer, boost pressure pushes out a spring tensioned rod that opens a flapper in the exhaust housing. When the flapper is open, some exhaust is bypassed around the exhaust turbine wheel.

The ECM reads manifold pressure, at 32# it sends a signal to a "valve" on the intake side of the turbo... which uses air pressure to open the WG, like a mech WG. So if you look there is a air line on the turbo to the WG.

Ah64 is wrong about the ecm, when the ecm wants to limit boost, it de energizes the solenoid so that it no longer vents boost pressure. Once 26 psi pressure hits the wastegate head, it pushes out the rod. The rod leads to a lever connected to wastegate puck, flapper, gate, whatever you want to call it.

Here are some pics of my HX 35 so you can better understand the mechanical portion of the wastegate:

Not really.It is a solenoid.when the ECM wants higher boost it will open an internal passage to bypass the boost signal from going to the actuator,allowing higher boost to be built.

Bob

Electronic Solenoid portion:

Instead of the little brass elbow like in this pic:



Your turbo has an electric solenoid. The solenoid has a small 2mm hole through the housing that connects it to pressurized air from the turbo. That hole allows pressurized air to enter a tee like internal fitting. One end to the tee 2mm part gets pressurized air, one end of the tee, about 3mm leads to the silicone hose. And third end of the tee leads to a compartment that is sealed off with a neoprene flat washer. When the solenoid receives power from the ecm, is lifts the neoprene washer at the top of the compartment and lets pressure vent. This vent is 4-5mm in size so it vents more air than the 2mm tee can let into the system. Because pressure is vented, zero pressure travels down leg 2 of the tee to push on the wastegate head. Most of the time, this solenoid does not receive power. Most of the time boost is directly fed to the wastegate head. Most of the time 26 psi boost is the limit because that is what it takes for the head to push hard enough to open the waste gate. Occasionally the ECM wants boost to raise more than 26 psi. When the ECM thinks there is a need for more boost, it sends a PWM pulse width modified signal to the solenoid. Like explained above this signal causes the solenoid to withdraw an internal rod that pulls back the sealing neoprene washer and causes the third leg of the tee to vent all of the pressurized air that is coming in from the 2mm leg and thus the #2 silicone hose leg does not receive sufficient pressure to operate the wastegate head.

If you still cannot follow my ramblings, take the solenoid off your turbo and look at it, you should be able to figure it out in two minutes.

BOB is correct, he said in three words what I tried to say in 300.

Thanks.........