Low boost, no boost problem
 

Hi guys. I just got my 2000 ssei running yesterday, car had an engine fire and I just replaced engine tranny and wire harness from one car to another. Car runs nicely but I noticed The boost only goes up to about 1 or 2 psi when Wide open throttle. I tried this different times and never could get it much past zero. I don't understand whats going on..Any help would be much appreciated. Thanks. Car has 58k miles and new engine and tranny have 73500 miles on them. Nothing taken apart, just switch from one vehicle to the other.
J

Check the boost control solenoid. It control the opening and closing of your boost control valve. If the valve is not closing and staying open, your boost is vented.

A lot of boost gauges just don't work, mine shows 1 or 2 and it doesn't have the electric boost control solenoid, if you really wanna know your boost get an aftermarket gauge

If you have access to a scanner, check it that way. You can't always trust the stock gauges. Also, with engine running, flip the throttle open by hand and watch the boost control, does it move?

I am going to check out the boost solenoid and valve this evening. But I am worried now since last night when I got home I could see a little smoke coming from around the bottom of the exhaust manifold, I have just replaced that valve cover gasket when I put the engine in. I fear I may have a head gasket seeping oil and losing a bit of compression..would that effect my boost? I will post more as I find out..
J

Ok, I just checked the boost valve and it opens by vacuum. It opens all the way up when I have the engine running and open the throttle all the way up for an instant..it opens instantly also. No problem there obviously. Any other suggestions? I have another instrument cluster to put in later to see if it is a bad gauge..but I doubt it at this point.
J

First post, it's unlikely you have a bad head gasket, more likely you have a valve cover gasket leaking.

I would put money on the fact you have a bad gauge.

x2 on the gauge, superchargers aren't like turbos where you can vary the boost, for X pully size you will get up to X psi of boost

Please define what you mean by "it opens all the way". When the car is not running, the arm on the boost control actuator will be fully extended. When you start the car, the arm "pulls up" into the actuator. Under WOT the arm will again extend (to the position it is in when the car is not running) to open the S/C gate valve. In other words, when the arm is retracted into the actuator you have no boost. When the arm is extended out of the actuator you have full boost.

One test you might want to try is to remove and plug the vacuum lines gong in to and out of the actuator (this will mean the actuator will not move from the fully extended position it is in when the car is not running) and take the car for a drive. This will give you full boost at all times, regardless of throttle position. If you notice a difference in boost, your problem is a bad bcs or bca. Do not drive the car like this for more than a quick test, or the gods of engine damage will pay you a visit.

Good news..after looking at my other bonneville and another post, I see that my arm on the actuator was not going all the way back down..the car had sit all summer and the arm would stick about mid way down and wouldn't return. I used some good ole WD40 and worked it back and forth and it straightened right up. I got about 5psi boost max on the drive after that. I am satisfied now. All though I would like to change that pulley size but also want to keep it safe without any engine problems or runnability problems..what size pulley can I safely switch too? Thanks for all the help. J