My car will only achieve around 2 to 3 psi boost. By pulling the vacuum line off and on from the top of the BCA with the car idling, I was able to observe the boost control actuator arm is traveling fully. Up with vacuum, down with no vacuum. I did the BCS bypass by disconnecting the vacuum hose that runs from the BCS to the BCA (removed at the BCS) and plugging it, but there was no improvement. If anything, it dropped boost by 1/2 psi.

I then tried removing and plugging both vacuum lines from the BCA, which means the actuator arm is fully extended at all times, and the waste gate is wide open. Now I get 7 psi, and probably could get more but I didn't want to drive the car too long like this.

Therefore, the BCA is working, but I am not sure the problem is the BCS because the BCS bypass test did not yield higher boost levels.

The BCS test proceedure I used was posted by Toddster (thanks Toddster) for a 1992 - 1999, and mine is a 2001.

Either the BCS on my 2001 functions differently than Toddster'* 95, or something else other than the BCA or BCS is causing me to lose boost.

Does anyone have any comments or suggestions?

Roy

Hi Roy,

A bad MAP sensor or one with bad vacuum going to it will limit the amount of boost your SC'r produces. The MAP sensor does feed off of the fuel pressure regulator vac/boost line, so it would be good to check it just to make sure the vacuum lines are good. In fact check all your vacuum lines.

Unfortunately there is no easy way to trouble shoot a bad MAP sensor. You could change it out with another known working one to see if things change for the better.

Or go here -----> https://www.gmforum.com/t280296/

Manifold Absolute Pressure

The 2000+* only have one, so my knowledge there is limited.

Todd.

Thanks Todd. I will definitely check out the MAP sensor. I have a feeling it is okay because when I scan it, the readings (when adjusted by subtracting barometric pressure) seem to make sense. High vacuum at idle, positive pressure at WOT, etc. I will follow the test procedure Danthurs posted.

Question. Does the MAP sensor feed off the boost (determines the air pressure that is created by the boost) or does it initiate the boost? The BCS operates the BCM. What tells the BCS boost is called for? Is it the MAP sensor?

Roy

Does anyone know where I can get a boost control solenoid for a 2001 Bonneville SSEi? I looked at O'Reilly'*, RockAuto and GMpartsdirect, but either I can't find it, or they don't have it.

Roy

Do you have any local salvage yards? The pick and pulls are the best.

Not many salvage yards in my area, and the likelihood of finding a Bonneville SSEi of the same vintage as mine is pretty slim.

Several people have commented in various threads the a BCS is not expensive, so someone (other than the stealership) must sell them.

2 or 3 psi is really low even for a stock 2000+ SSEi. I was getting 6 or 7 PSI just with a gutted airbox.

Yes, I know. That'* why I am trying to fix it.

The boost control solenoid for a Gen II L67 part number is 1997244, and it is called a "valve". The stealership wants $42.31, gmpartsdirect wants $25.08 + $13 shipping, and someone is selling them on Ebay for $25, shipping included.

I am still not sure the problem is the BCS, but for $25 I will replace it and see what happens.

Roy

Did you take a look at Auto Parts Fast at RockAuto

Rock Auto is always the first place I look. Couldn't find it in the catalogue, and the part number look up area did not recognize the part number.