Okay guys, I’ve been chasing this problem and reading as much as I can find for almost a month now, but to no avail. I purchased this TR last fall and have been very happy with it so far. I have literally done nothing to the car except change the oil and clean it up. I have only driven it about 150 miles so far. There was an owner in the middle but, the car originally belonged to Dave (Wazvette), motor & trans was put together by Discostu & JDfastGN, and as I said the car runs VERY well.
http://www.turbobuick.com/forums/threads/fully-built-street-gn-hardtop-gt70hpq-priced-to-go.300020/
http://www.turbobuick.com/forums/threads/87-grand-national-hardtop-650-whp.360293/
Anyway, after having the car out for about a 30 minute drive, (read in; easy cruise, fully warmed up), I lay in to the throttle at about 5o mph in drive, I feel the car downshift and, POP, a single not excessively loud backfire. I immediately pulled out of it and cruised for about a mile listening and checking everything, (gauges, scanmaster, etc.), looking for anything wrong. Finding nothing I repeat the experiment
, this time as I put the throttle down the car accelerates smoothly, but no boost for about 5 - 6 seconds or until the rpm's reach about 4000 rpm. I try it one more time with the same results. No smoke, no weird noises (hissing, whining, grinding, etc.), nothing unusual except no boost until the upper rpm range. Once the boost eventually comes on, the car pulls hard, but doesn't seem quite as strong as before, (might just be me) and when I let out of it I still hear the wastegate fluttering. Over the past several weeks I have checked many things, (boost hoses, clamps, vacuum lines, fuel pressure, volts, plugs, wires, blowby, etc. etc. etc.). I also recorded a powerlogger file and compared it to previous runs. The only difference is the boost coming up SLOWLY. Everything else seems fine and as I said, so far I have changed nothing. Today I pulled the wastegate actuator, checked the wastegate movement, and the actuator movement. The actuator seemed strong, (pulled hard and pulled back quickly). One interesting note, on the test drive today when nothing improved, I completely disconnected the boost line to the actuator and got the same results. I am left to feel that the problem has to lie in the wastegate, actuator, or turbo, but I don't like just throwing darts at a problem and hope I hit it. The wastegate actuator seems logical, but... Any suggestions would be GREATLY appreciated.. Thanks. Dave.
http://www.turbobuick.com/forums/threads/fully-built-street-gn-hardtop-gt70hpq-priced-to-go.300020/
http://www.turbobuick.com/forums/threads/87-grand-national-hardtop-650-whp.360293/
Anyway, after having the car out for about a 30 minute drive, (read in; easy cruise, fully warmed up), I lay in to the throttle at about 5o mph in drive, I feel the car downshift and, POP, a single not excessively loud backfire. I immediately pulled out of it and cruised for about a mile listening and checking everything, (gauges, scanmaster, etc.), looking for anything wrong. Finding nothing I repeat the experiment
, this time as I put the throttle down the car accelerates smoothly, but no boost for about 5 - 6 seconds or until the rpm's reach about 4000 rpm. I try it one more time with the same results. No smoke, no weird noises (hissing, whining, grinding, etc.), nothing unusual except no boost until the upper rpm range. Once the boost eventually comes on, the car pulls hard, but doesn't seem quite as strong as before, (might just be me) and when I let out of it I still hear the wastegate fluttering. Over the past several weeks I have checked many things, (boost hoses, clamps, vacuum lines, fuel pressure, volts, plugs, wires, blowby, etc. etc. etc.). I also recorded a powerlogger file and compared it to previous runs. The only difference is the boost coming up SLOWLY. Everything else seems fine and as I said, so far I have changed nothing. Today I pulled the wastegate actuator, checked the wastegate movement, and the actuator movement. The actuator seemed strong, (pulled hard and pulled back quickly). One interesting note, on the test drive today when nothing improved, I completely disconnected the boost line to the actuator and got the same results. I am left to feel that the problem has to lie in the wastegate, actuator, or turbo, but I don't like just throwing darts at a problem and hope I hit it. The wastegate actuator seems logical, but... Any suggestions would be GREATLY appreciated.. Thanks. Dave. 
