Car is a 92 DSM turbo.

I bought a new ECU since my old one died on me. After I installed it I took it for a run on the highway. It kept boosting all the way to fuel cut at 28psi. The turbo I have on there is only effective until about 22-24psi.

Thinking I had a bad MBC, I pulled it off and put the stock system back on, which should limit it to 13psi. It still did the same thing, so I did a boost leak check got no leaks.

I'm out of ideas since the BCS is hooked right to the wastegate, which opens and closes. No leaks in hoses either. Any ideas?

Is there a pill in the line you are using? If not, Run the comp outlet directly to the wastegate and see what you get. I'm assuming this is an internal wastegate. If not, do you have the pressure reference to the right nip?

Yes its an internal wastegate. I hooked it up directly with a single tube. The wastegate still works. It is the ECU I hooked up a normal ECU and it worked perfectly. Thanks for the help.

did you bypass the factory BCS?

glad you got it worked out. That's weird that the ecu caused that