I've got an '88 740 turbo. The turbo seems to be malfunctioning. I have not had the car long but when I first got it at idle and steady acceleration the needle on the boost gauge pointed to about 8 o'clock and only went into the boost range unless one was accelerating somewhat hard. I could cruise at 80 without the turbo being on. Now the turbo hovers at 11 o'clock and easily goes into turbo range even at moderate acceleration, or at about 70-75 on the interstate. Any ideas what might be the problem? My friend thinks it may be in the bypass valve as the turbo seems to be boosting even at idle. Thanks in advace.

~~~Slates