[MA70-3.0GT]

Never mind, I found the thread & linked it now...

http://www.toyota-supra.info/forums/...o-problem.html

So from what you're saying the boost is going through the roof & then the motor cuts out until it drops off? (known as fuel cut, designed to save the engine in case of a stuck wastegate)

If so then yes, you could have a stuck 'gate but as you say it happened after you gutted the cat you may have damaged/dislodged the actuator pipe or rod whilst working on the exhaust. Look at the bottom of the compressor housing under the intake pipe fitting & you'll see a small diameter (1/2") hose going from the turbo outlet to the wastegate actuator, check this is not split (for what it's worth change it anyway) and is securely clipped on at both ends.

If it is OK then you can do a simple check to see if the actuator is working or not. Apply (using a bicycle pump or similar with a gauge) no more than about 10psi to the actuator. The rod should start to move at about 7psi. I can't stress enough NO MORE than 10psi by the way... (actually the tsrm says 11.4 but hey...)

OK, so if you've done this & the rod IS moving as it should then all I can think of is you may have bent the actuator rod while working on the 'zorst... Either way make sure you fit a good bit of hose to the actuator & clip it on securely & then see if it's cured before spending out on parts you may not need.

Damn I'm crap at describing how to do stuff, hopefully this helps & you can get sorted without spending out again...