Nissan Frontier. Instruction — part 415
P0171 FUEL INJECTION SYSTEM FUNCTION
EC-231
< DTC/CIRCUIT DIAGNOSIS >
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Check the following.
• Fuel pump and circuit (Refer to
.)
• Fuel pressure regulator (Refer to
• Fuel lines
• Fuel filter for clogging
>> Repair or replace.
6.
CHECK MASS AIR FLOW SENSOR
With CONSULT
1. Install all removed parts.
2. Check “MASS AIR FLOW” in “DATA MONITOR” mode with CONSULT.
With GST
1. Install all removed parts.
2. Check mass air flow sensor signal in Service $01 with GST.
OK or NG
OK
>> GO TO 7.
NG
>> Check connectors for rusted terminals or loose connections in the mass air flow sensor circuit or
grounds. Refer to
EC-168, "Component Description"
.
7.
CHECK FUNCTION OF FUEL INJECTOR
With CONSULT
1. Start engine.
2. Perform “POWER BALANCE” in “ACTIVE TEST” mode with CONSULT.
3. Make sure that each circuit produces a momentary engine speed drop.
Without CONSULT
1. Start engine.
2. Listen to each fuel injector operating sound.
OK or NG
OK
>> GO TO 8.
NG
>> Perform trouble diagnosis for
.
8.
CHECK FUEL INJECTOR
1. Confirm that the engine is cooled down and there are no fire hazards near the vehicle.
2. Turn ignition switch OFF.
3. Disconnect fuel injector harness connectors.
4. Remove fuel injector gallery assembly. Refer to
EM-39, "Removal and Installation"
Keep fuel hose and all fuel injectors connected to fuel injector gallery.
The fuel injector harness connectors should remain connected.
At idling:
1.0 - 4.0 g/s
At 2,500 rpm:
4.0 - 12.0 g/s
At idling:
1.0 - 4.0 g/s
At 2,500 rpm:
4.0 - 12.0 g/s
Clicking noise should be heard.
PBIB1986E
EC-232
< DTC/CIRCUIT DIAGNOSIS >
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P0171 FUEL INJECTION SYSTEM FUNCTION
5. Disconnect all ignition coil harness connectors.
6. Prepare pans or saucers under each fuel injector.
7. Crank engine for about 3 seconds. Make sure that fuel sprays
out from fuel injectors.
OK or NG
OK
>> GO TO 9.
NG
>> Replace fuel injectors from which fuel does not spray
out. Always replace O-ring with new ones.
9.
CHECK INTERMITTENT INCIDENT
Perform
GI-42, "Intermittent Incident"
.
>> INSPECTION END
Fuel should be sprayed evenly for each fuel injector.
PBIB1726E
P0172 FUEL INJECTION SYSTEM FUNCTION
EC-233
< DTC/CIRCUIT DIAGNOSIS >
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P0172 FUEL INJECTION SYSTEM FUNCTION
On Board Diagnosis Logic
INFOID:0000000009480889
With the Air-Fuel Mixture Ratio Self-Learning Control, the actual mixture ratio can be brought closely to the
theoretical mixture ratio based on the mixture ratio feedback signal from the A/F sensor 1. The ECM calcu-
lates the necessary compensation to correct the offset between the actual and the theoretical ratios.
In case the amount of the compensation value is extremely large (The actual mixture ratio is too rich.), the
ECM judges the condition as the fuel injection system malfunction and lights up the MIL (2 trip detection logic).
DTC Confirmation Procedure
INFOID:0000000009480890
NOTE:
If DTC Confirmation Procedure has been previously conducted, always turn ignition switch OFF and wait at
least 10 seconds before conducting the next test.
WITH CONSULT
1. Start engine and warm it up to normal operating temperature.
2. Turn ignition switch OFF and wait at least 10 seconds.
3. Turn ignition switch ON and select “SELF-LEARNING CONT” in “WORK SUPPORT” mode with CON-
SULT.
4. Clear the self-learning control coefficient by touching “CLEAR”.
5. Start engine.
If it is difficult to start engine, the fuel injection system has a malfunction.
Performing the following procedure is advised.
a. Crank engine while depressing accelerator pedal.
NOTE:
When depressing accelerator pedal three-fourths (3/4) or more, the control system does not start the
engine. Do not depress accelerator pedal too much.
b. If engine starts, go to
.
If engine does not start, remove ignition plugs and check for fouling, etc.
6. Keep engine at idle for at least 5 minutes.
7. Check 1st trip DTC.
8. The 1st trip DTC P0172 should be detected at this stage, if a malfunction exists. If so, go to
NOTE:
If 1st trip DTC is not detected during above procedure, performing the following procedure is advised.
a. Turn ignition switch OFF and wait at least 10 seconds.
b. Start engine.
c. Maintain the following conditions for at least 10 consecutive minutes.
Hold the accelerator pedal as steady as possible.
CAUTION:
Always drive vehicle at a safe speed.
Sensor
Input Signal to ECM
ECM function
Actuator
Air fuel ratio (A/F) sensor 1
Density of oxygen in exhaust gas
(Mixture ratio feedback signal)
Fuel injection control
Fuel injector
DTC No.
Trouble diagnosis name
DTC detecting condition
Possible cause
P0172
0172
Fuel injection system too
rich
• Fuel injection system does not operate properly.
• The amount of mixture ratio compensation is too
large. (The mixture ratio is too rich.)
• Air fuel ratio (A/F) sensor 1
• Fuel injector
• Exhaust gas leaks
• Incorrect fuel pressure
• Mass air flow sensor
VHCL SPEED SE
50 - 120 km/h (31 - 75 MPH)
EC-234
< DTC/CIRCUIT DIAGNOSIS >
[QR25DE]
P0172 FUEL INJECTION SYSTEM FUNCTION
d. Check 1st trip DTC.
e. If 1st trip DTC is detected, go to
WITH GST
1. Start engine and warm it up to normal operating temperature.
2. Turn ignition switch OFF and wait at least 10 seconds.
3. Disconnect mass air flow sensor harness connector.
4. Restart engine and let it idle for at least 5 seconds.
5. Stop engine and reconnect mass air flow sensor harness con-
nector.
6. Select Service $03 with GST. Check that DTC P0102 is
detected.
7. Select Service $04 with GST and erase the DTC P0102.
8. Start engine.
If it is difficult to start engine, the fuel injection system has a mal-
function.
Performing the following procedure is advised.
a. Crank engine while depressing accelerator pedal.
NOTE:
When depressing accelerator pedal three-fourths (3/4) or more, the control system does not start the
engine. Do not depress accelerator pedal too much.
b. If engine starts, go to
If engine does not start, remove ignition plugs and check for fouling, etc.
9. Keep engine at idle for at least 5 minutes.
10. Check 1st trip DTC.
11. The 1st trip DTC P0172 should be detected at this stage, if a malfunction exists. If so, go to
NOTE:
If 1st trip DTC is not detected during above procedure, performing the following procedure is advised.
a. Turn ignition switch OFF and wait at least 10 seconds.
b. Start engine.
c.
Maintain the following conditions for at least 10 consecutive minutes.
Hold the accelerator pedal as steady as possible.
CAUTION:
Always drive vehicle at a safe speed.
d. Check 1st trip DTC.
e. If 1st trip DTC is detected, go to
Diagnosis Procedure
INFOID:0000000009480891
1.
CHECK EXHAUST GAS LEAK
1. Start engine and run it at idle.
2. Listen for an exhaust gas leak before three way catalyst (manifold).
VHCL SPEED SE
50 - 120 km/h (31 - 75 MPH)
BBIA0622E
PBIB1216E
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