boost under load?

[maverick_935]

I have n issue that happens once in awhile and I cannot duplicate it. Once in awhile while accelerating the boost sounds and acts like it blows off.

Any ideas?

[Kennedy]

Is your EGR system still operational?

[maverick_935]

yes i haven't put in the bypass or the electronics yet.

[Kennedy]

A sudden reduction in exhaust (drive) pressure can cause the pressurized air in the intake to momentarily reverse (turbo bark) causing the turbo wheel to slow/stop. This issue is actually noted in a GM bulletin several years back as this condition was apparently occurring in otherwise stock trucks when the EGR system activated. The GM solution was in programming to reduce the EGR duty cycle (opening) therby maintaining more exhaust pressure and lower EGR flow. My solution of course is also in the programming, but a much more aggressive approach.