Hummer H1 Service Manual page 55

_____________________________________________________________________
2-18 Engine
PROBLEM
Low Power Poor 1.
Acceleration
(Black smoke not
evident at 1/2 to
wide open
throttle)
Low Power, 1.
Poor Accelera-
tion (Black 2.
smoke evident
at 3/4 to wide
open throttle) 3.
4.
5.
6.
7.
8.
Turbocharger 1.
Noise
2.
Blue Exhaust 1.
Smoke with
Warm Engine
Only 2.
3.
4.
Turbocharger Diagnosis
POTENTIAL CAUSE
Lean fuel mixture caused by insufÞcient fuel
volume or pressure.
Air Þlter plugged.
Restriction in air intake duct to turbocharger
compressor wheel.
Air leak in turbocharger compressor inlet and
outlet ducts. May be accompanied by high
pitch whine indicating system air leak.
Loss of vacuum to wastegate actuator, or actu-
ator is damaged.
Air leak at intake manifold.
Exhaust leak between cylinder head ports and
turbine inlet of turbocharger.
Turbocharger damaged internally.
Fuel system problem (over-rich mixture).
Obstruction in air intake or outlet systems
may cause high pitch whine.
Compressor/turbine impeller contacting hous-
ing, or other internal damage. May be accom-
panied by vibration.
InsufÞcient intake air volume.
Partially plugged oil drain tube.
Oil Leaking past worn compressor or turbine
side seals.
Engine problem caused by worn rings, or
valve seals.
CORRECTION
1. Problem is in fuel delivery system. Check fuel
supply pump pressure, look for leaks in lines and
at Þttings, plugged fuel Þlter, accelerator cable
problem, injection pump problem. Refer to low
power information in guides for standard diagno-
sis.
1. Replace Þlter.
2. Remove and inspect duct components. Remove/
repair any restrictions.
3. Disassemble, inspect, repair worn, damaged,
loose parts.
4. Check vacuum supply. Replace hose and Þttings
if necessary. If OK, use hand operated vacuum
tester to check actuator operation. Replace actu-
ator or vacuum pump, as required.
5. Tighten loose bolts. Or, remove manifold and
replace gaskets if necessary.
6. Check exhaust manifolds pipes, and turbo-
charger connections for leaks. Replace damaged
components, tighten loose fasteners.
7. Remove and inspect turbocharger. Replace if
compressor/turbine wheels, or other internal
components are damaged.
8. Refer to low power information in standard diag-
nosis.
1. Disassemble and clear blockage, or restriction.
2. Replace turbocharger.
1. Disassemble, inspect, and clear any restrictions.
Replace damaged, worn ducting parts.
2. Remove and clear tube. Replace tube if fully
plugged, pinched, or kinked.
3. Replace turbocharger.
4. Overhaul cylinder heads or engine as needed.
¨