Great Wall GW491QE, Руководство по обслуживанию

Страница: 76 / 222

EF.1-57
Fault code
：
P0171 The self-adaptive value for a closed-loop control of air /fuel ratio is beyond the upper limit.
”
Note: The diagnosis flow process below is applicable to cases excluding that fault codes are produced simultaneously on
inlet-air pressure sensor, carbon-canister control valve, oxygen sensor, etc. If fault codes are produced simultaneously, settle
other failures first before performing a check and repair as per the flow process below.
S.N. Operation steps
Check
result
Follow-up steps
1
Connect with the diagnosis instrument, and place the ignition switch to the
ON
”
position.
Next step.
Yes Next step.
2
Start the engine and have it running at idle-speed until the cooling-fluid
temperature reaches its normal value. When under a full working condition,
observe the change of value at the item
oxygen sensor voltage
”
on diagnosis
instrument, and whether the displayed value remains at about 100mV(yet
with less changes) for a long-term period when under some working
conditions.
No Diagnosis help.
Yes Next step.
3
After the connection with fuel manometer (the connection point is on the front
end of fuel inlet pipe included in the fuel distributing pipe assembly), check
whether the fuel pressure keeps at about 260 kpa while engine is running at
idle-speed; and whether the fuel pressure keeps at about 300kpa after vacuum
pipe has been pulled away from the fuel pressure adjustor.
No
Check and repair the fuel
system.
Yes
Repair or change the wiring
harness.
4
Check whether respective loops between Pin 36 &18 of ECU and the
connection pin A (corresponding to the grey connection line of oxygen sensor)
&B (corresponding to the black connection line of oxygen sensor) of sensor
are short circuit to ground.
No Next step.
Yes
Check and repair it based
on diagnosis.
5
A
、
Check whether severe air leakage exists in the air inlet system;
B
、
Whether fuel injector has been blocked;
C
、
Whether the clearance of spark plug is too big;
D
、
Whether the resistance of fire division line is too big;
E
、
Whether the clearance of air valve is too big;
So on and so forth.
No Diagnosis help.
Fault code: P0172 The self-adaptive value for a closed-loop control of air /fuel ratio is beyond
the lower limit
”
Note: The diagnosis flow process below is applicable to cases excluding that fault codes are produced simultaneously on
inlet-air pressure sensor, carbon-canister control valve, oxygen sensor, etc. If fault codes are produced simultaneously, settle other
failures first before performing a check and repair as per the flow process below.
S.N. Operation steps
Check
result
Follow-up steps
1
Connect with the diagnosis instrument, and place the ignition switch to the
ON
”
position.
Next step.
Yes Next step.
2
Start the engine and have it running at idle-speed until the cooling-fluid
temperature reaches its normal value. When under a full working condition,
observe the change of value at the item
oxygen sensor voltage
”
on diagnosis
instrument, and whether the displayed value remains at about 900mV(yet
with less changes) for a long-term period when under some working
conditions.
No Diagnosis help.
Yes Next step.
3
After the connection with fuel manometer (the connection point is on the front
end of fuel inlet pipe included in the fuel distributing pipe assembly), check
whether the fuel pressure keeps at about 260 kpa while engine is running at
idle-speed; and whether the fuel pressure keeps at about 300kpa after vacuum
pipe has been pulled away from the fuel pressure adjustor.
No
Check and repair the fuel
system.
Yes
Repair or change the wiring
harness.
4
Check whether respective loops between Pin 36 &18 of ECU and the
connection pin A (corresponding to the grey connection line of oxygen sensor)
&B (corresponding to the black connection line of oxygen sensor) of sensor
are short circuit to power supply.
No Next step.
Yes
Check and repair it based
on diagnosis.
A
、
Whether the injector is leaking;
B
、
Whether the exhaust pipe has been blocked;
C
、
Whether the clearance of air valve is too small;
So on and so forth.
No Diagnosis help.
M7.9.7 system service &diagnosis flow process based on fault code
ProCarManuals.com