MPI <4G9> -
Troubleshooting
13A-93
Check the harnesses between the
air flow sensor and the engine-ECU
<M/T> or engine-A/T-ECU <A/T> and
between the air flow sensor and the
engine control relay, and repair if
necessary.
OK
NG
Replace the engine-ECU <M/T> or
engine-A/T-ECU <A/T>.
OK
Check the trouble symptoms.
NG
Check the following connectors:
A-99, B-34 <M/T>, B-94 <A/T>
NG
Repair
Check the trouble symptoms.
NG
Replace the air flow sensor.
OK
Measure the output waveform at air
flow sensor connector A-99 (by
using an analyzer).
D
Use test harness (MB991709) to
connect the connector, and
measure at the pick-up harness.
D
Engine: Idling
D
Voltage between terminal 3 and
earth
OK:
Waveforms should be dis-
played on P.13A-166 (In-
spection Procedure Using
an Analyzer) and noise
should not be displayed in
the waveform.
NG
Replace the engine-ECU <M/T> or
engine-A/T-ECU <A/T>.
OK
Check the trouble symptoms.
OK
Check the harness between the air
flow sensor and the engine-ECU
<M/T> or engine-A/T-ECU <A/T>.
NG
Repair
NG
Check the following connector:
A-99
NG
Repair
OK
Measure at air flow sensor connector
A-99.
D
Use test harness (MB991709) to
connect the connector, and
measure at the pick-up harness.
D
Voltage between terminal 7 and
earth
OK:
Engine: Idling
0 - 1 V
Engine speed: 3,000 r/min
6 - 9 V
OK
Replace the air flow sensor.
OK
Check the harness between the air
flow sensor and the engine-ECU
<M/T> or engine-A/T-ECU <A/T>.
NG
Repair
NG
Check the following connector:
A-99
NG
Repair
OK
Measure at air flow sensor connector
A-99.
D
Use test harness (MB991709) to
connect the connector, and
measure at the pick-up harness.
D
Ignition switch: ON
D
Voltage between terminal 7 and
earth
OK:
7 - 8 V
From the previous page