willizm

iTrader: (10)

Hi all, I had my car dyno tuned at AMS about a month ago and we had a few issues with boost starting to taper toward redline. as we increased boost using a truboost controller the taper became more pronounced. The base spring pressure would taper from 10psi to 8psi. With the truboost controller we would get 12psi to 9psi, and 15.7psi to 11psi. As we raise boost the taper becomes more severe.

I took apart the wastegate and I see a couple things. A. the diaphragm is pinched and honestly was like that since I got it and B. I notice there is some buildup on the flange side that meets the crossover.

So, does this sound like my culprit or are there other things I should look for? According to AMS the hot and cold sides were pressure checked. My 3" DP is dumped under my pedals, TC78 is an .96AR housing, forged 347ci ls1.

Thanks all.