snoopster76

Can someone explain to me how these parts work?
Ext. Wastegate actuator?
Switching Actuator?
Blow off Valve?

I'm trying to get my blow off valve to vent on my car, it works fine on my buddy's car but not mine. His vaccum hose from the valve is connected to the switching actuator and the wastegate actuator goes to his boost pressure sensor and the manifold through a tee.

Also, after removing the egr valve, the air pump and the valve it is connected to, what do you do with the electrical connectors?

Keith

You mentioned a switching actuator. This means this car is an 87-88 TII. Assuming that to be true, here are the part identifications.

Wastegate actuator: Opens when the turbo boost pressure exceeds a certain value. Somewhere between 5 and 7 PSI, I think. When it opens, exhaust gasses bypass the exhaust turbine of the turbocharger. This prevents overboost. The valve is attached to the bottom of the turbocharger (hence, external). A hose goes to a nipple on the tube on the pressure side of the intake turbine.

Switching actuator: This device is bolted to the exhaust manifold. It closes an actuator inside the manifold when vacuum is applied to it by the Twin Scroll Turbocharger Solenoid Valve. This happens at low rpm so the exhaust gasses will be redirected to the center of the exhaust turbine blades for faster spoolup.

Blowoff valve: Black valve sitting between pressure side of intake pipe and Turbo Inlet Duct. Manifold vacuum goes to it. When the vacuum is high enough, the valve opens. If the turbo is spinning, pressure will be vented back to the TID. If it is vented to the atmosphere, a check valve is necessary (you have a huge vacuum leak when there is no boost/high manifold vacuum) and the TID must be plugged.

As for the electrical connectors, put a plastic bag around them, or just let them hang. This ECU is not smart enough to know they are disconnected.

Hope this helps.

Irv, Keith's dad

snoopster76

keith,

thanks alot. I'm new to this and was trying to figure out why my bov doesn't hiss on my car but does on buddy's. Am I not getting enough boost? Also, if the waste gate actuator works off vacum, why would someone hook the vaccum line to the boost pressure sensor which doen't produce vaccum? Thanks again.

Keith

In answer to your first question, am I getting enough boost, there are a number of checks you can do to determine that. The easiest method is the seat-of-the-pants dyno test. Does the car pull really strong at high rpm? If it does, you are getting plenty boost. Does your boost guage read at least 20? Again, if it does, you are ok, but you can't always depend on the factory boost guage. If you can check it with a real guage, so much the better.

OK, the waste guage actuator works off of Pressure! The hose that connects it goes straight to the pressure (intercooler) (output) side of the turbocharger.

The boost pressure sensor is just that, a sensor, it produces nothing! The "vacuum" line attached to it comes off of the intake manifold. It will send vacuum to the sensor when there is vacuum, and pressure to the sensor under boost. This is ok, since the boost/pressure sensor has a range of 20" of vacuum to over 10 psi of boost. Oh, yes, your factory boost guage gets its input from this sensor also. Both the ECU and the guage are connected via the 4-wire electrical connector found on this sensor.

Why no hisss? No boost would be one possibility. Vacuum leak in the vacuum hose connecting to the BOV is another (the valve needs at least 11" vacuum to open). A vacuum leak somewhere else could cause this. Oh, and last but not least, the check valve plays a major role in what this will sound like - I've heard some check valves sound like a fart instead of a hissss.

Irv, Keith's dad