I have a 95 850T with the IPD ECU and exhaust upgrade and it ran well this morning. Now tonight I can't get the boost gauge above 3/4 of the way up and the power it limited. This morning it would go to top of white or off the white a little. I noticed a loud hissing noise when I step on it tonight. I checked the converter to see if it was glowing when I got home thinking maybe it was clogged but it seemed to be ok. I don't know what else to check. As long as I am not on boost it seems to run fine. Has this happened to anyone else?

As another person already suggested, check the boost hoses. On my wife's car, the hose at the TOP in middle had a big ol' hole in it.

Those hoses get oil-soaked and decay over time. Then, one day, you're cruising along, smack the accelerator, pick up some boost and BLAM! pops a hole.

New hose isn't cheap, but neither was your performance ECU :-)

Also, you may want to look at the (can't think of the name of it) device that dumps the pressure when you take your foot off the accelerator. Those bolts could be loose.

May have a split pressure hose or intercooler problem. Inspect the hose from the turbo pressure side to the intercooler, and from intercooler to throttle body. Also have a look at the intercooler tanks if no hose problems found.

Look at the wastegate and see if it is operating properly. I had an 850 turbo with stock ECU. One day, I hit the gas real hard because I hated the lazy spool of the turbo. Well gues what?: Car went slow. It drove properly as long as I didn't use the turbo. Checked the codes on the vehicle and some were off. After clearing all the codes I heard a hissing sound coming form the turbo area. Seems I got tsomething jammed that finally released. Car worked fine after that. Check your codes and clear them all.

Delgado