Another loss of boost question

[fleastang]

I had someone bring over a 2002 7.3 that started making a horn like sound under heavy acceleration. The truck has a TS Perf 6pos chip, 4" exhaust w/muffler delete, air filter mod, and guages. It will not build more than 12 psi boost at full throttle (half of what it was), and the EGT's are going up too fast with all the fuel. I checked all intercooler boots and connections. The MAP sensor hose is okay and when you shut off the truck you can hear the turbo spooling down as it did before this issue started. The loud horn like sound at full throttle appears to come from the middle of the firewall area under the hood. Is it a wastegate issue? I am at a loss..........thanks for any help.

[fleastang]

Anybody????? What is the best way to check the wastegate and if it is the problem? I would assume from the noticeble sound (inside the cab and standing in the driveway when someone drives it down the street) that the boost pressure is forcing a leak or blow by somewhere??? Thanks if someone can help out!!

[szyd]

I would check the exhaust from the manifolds to the turbo. It sounds to me as if you are loosing drive pressur.