I just got the car back on the road after fixing the header, and the first time out it seemed to me that the boost was lower than normal during acceleration. So I run at WOT in 2nd gear to see how much boost I'm making, and I get only to 11-12 psi ! Previously, I would be at 16-17psi. At the same time, the SES and ASC lights came on.

The code is P0108, and the boost gauge appears to work normally, and vacuum is very good (between -25 and -30 mmHg) going down hill. The car feels more sluggish that it should, not terrible, just a bit under the weather. I haven't had a chance to check the VGS connections under the IC, I'll do this tonite. It just seems strange to have this combination of low boost with an overboost code. Any ideas? Thanks in advance.

 

I know this is a very old thread, but I found it on Google when searching for solutions to the same problem. For the benefit of others, one possible cause is a defective MAP sensor - this is the sensor that is visible on the intake manifold directly under the intercooler at the front of the car, near the yellow warning sticker above the radiator fan.