THEORY OF OPERATION - CONTINUED
FUEL SYSTEM - CONTINUED
Turbocharger with Wastegate.
Turbocharger has a wastegate to help improve emissions. Wastegate operation is controlled by boost pressure. At
high boost pressures, wastegate opens in order to decrease boost pressure. At low boost pressure, wastegate closes
in order to increase boost pressure.
When engine is operating under low boost conditions, a spring pushes on a diaphragm in canister. This action
moves actuating lever in order to close wastegate valve. Closing wastegate valve allows turbocharger to operate at
As boost pressure through line increases against canister diaphragm, wastegate valve is opened. When wastegate
valve is opened, turbocharger rpm is limited by bypassing a portion of exhaust gases. Exhaust gases are routed
through wastegate, which bypasses turbocharger turbine wheel.
Turbocharger bearings use engine oil under pres-
sure for lubrication and cooling. Oil comes in
through oil inlet port, then goes through passages
in center section to lubricate and cool bearings.
Oil from turbocharger passes through oil outlet
port in bottom of center section, then returns to
engine oil pan.