Couldn't get the link to work....But I'll trust whatever you say, seeing you have your own site about it!! I see now how the BCA works and which way the lever moves in boost mode. (Down when I throttle it, up when idling...) So what does the BCS do? Control the BCA? Because the BCA seems to be working correctly.

The PCM commands the BCS to control the BCA based on gear selected, engine load, and various other parameters.

Think of the BCS as the go-between for the BCA and the Computer.

So doesn't that mean the BCS is working, because the BCA is moving when you throttle it?

When you remove that vacuum line from the top of the BCA and it moves FULLY, it means the BCA is CAPABLE of full travel/full boost if it'* commanded to.

So now you move back to WHY it'* not fully travelling when commanded.

Man, quick replies!! Sorry to still be confused, but doesn't the BCS TELL the BCA to move when I throttle it? SInce it'* moving, isn't the BCS controlling it correctly? Or is that not how it works? Sorry to ask so many ??? about it.

Do you understand duty cycle? The BCS is either OPEN or CLOSED. But it varies this by pulsing a duty cycle. This is how it VARIABLY controls the BCA.

Aaahhhh...Variably....I didn't understand that part. Thanks for your help. I'm gonna get a BCS and let you know how I make out. Thanks!

Just a shot in the dark here, but have you tested the boost guage itself? Have you put a mechanical guage on the plenum to see what the pressure is when accelerating?

Motorhead, that'* a great idea, but in our rather extensive experience on this Forum, we have yet to see a single failure of a boost gauge. To take it even farther, we've yet to see a single failure of a MAP sensor on the Series 1 (which sole purpose is for a boost pressure indication).

Let'* stick to what we know are the most common failure modes.

Ordered the BCS today, $28. I'll let you know when it comes in.