Troubleshooting - BMW 745i Repair Instructions

Condition
Possible Cause Check / Adjust
I nsufficient power in charge
I
Charge pressure too low Check charge pressure (see
range
page 21)
-
Charge pressure too low
Air guiding parts leak Seal air guiding parts (connect-
ing hoses and hose clamps
must be installed correctly)
Air valve leaks
I
Check air valve, see page 24
I
(check compressor for damage
when seal is missing on piston)
I
Bypass valve does not close Check bypass valve:
I
Detach bypass valve, inspect
valve and valve seat (move
I
valve)
-
Shaft in turbocharger broken
I
Replace turbocharger
Charge pressure too high
Control line clogged
Clean controi l l ine
I
Control line leaks
!
Check control line for leaks
(visual inspection). Check adap
ters for correct and tight fit on
i
by pass valve and compressor.
(see notes in repair procedures
for removing bypass valve on
page 89)
Diaphragm of bypass valve Replace bypass valve
torn
II
Bypass valve seized! (does not
Check bypass valve:
I
open) Detach bypass valve, check
valve and valve seat (move
valve)
Engine knocks Ignition timing incorrect
Check/adjust ignition timing
I
(see page 17)
Engine knocks at high load 'Partial throttle enrichment Check partial throttle enrich-
malfunctions
ment, see page 23
Turbocharger howling at Turbocharger rotor imbalan-
Replace turbocharger
increasing load ced
Increasing hiss at increasing
Turbine housing flange dis- Replace turbocharger
load in warm state
torted .
. .
Pressure knock while coasting Air valve malfunctions
I
Check air valve
Check vacuum stop
,
Hesitation, no power when Safety switch closed _ Check safety switch
accelerat i ng
Charge pressure too high? Check charge pressure