Chery Tiggo. Manual — part 154
Check reference values between ECM terminals and ground under the following conditions:
ECM TERMINAL NO.
ITEM
CONDITION
DATA (AVERAGE DC
VOLTAGE)
6
Injector 2
• Engine is running
• Warm-up condition
• Idle
• Accelerate suddenly
Voltage: 11 - 14 V
7
Injector 3
27
Injector 1
47
Injector 4
ECM TERMINAL NO.
ITEM
CONDITION
DATA (AVERAGE DC
VOLTAGE)
17
Sensor (GND)
• Engine is running
• Warm-up condition:
78°C
• Idle: 795 RPM
• IAT: 36°C
• IAT signal: 1.88 V
0 V
33
Regulated sensor supply 1
Approximately 5 V
37
Air flow sensor
Approximately 322 kg/h
Approximately 1.39 V
On Board Diagnostic Logic
• Self-diagnosis detection logic.
DTC NO.
DTC DEFINITION
DTC DETECTION
CONDITION
DTC SET
CONDITION
POSSIBLE CAUSE
P0171
Fuel trim system too
lean
Engine is running
The amount of
mixture ratio
compensation is too
large (The mixture
ratio is too lean).
• Intake air leaks
• Air flow sensor
• Fuel injector
• Exhaust gas leaks
• Incorrect fuel
pressure
• lack of fuel
• Incorrect PCV
hose connection
• Upstream O
2
sensor
• ECM
DTC Confirmation Procedure:
Before performing the following procedure, confirm that battery voltage is more than 12 V.
• Turn ignition switch off.
• Connect the X-431 scan tool to the Data Link Connector (DLC) - use the most current software available.
• Turn ignition switch on.
• With the scan tool, record and erase stored DTCs in the ECM.
• Start engine and warm it to normal operating temperature, then select view DTC and data stream.
• If the DTC is detected, the DTC condition is current. Go to Diagnostic Procedure - Step 1.
• If the DTC is not detected, the DTC condition is intermittent (See Diagnostic Help and Intermittent DTC Trou-
bleshooting in Section 03 Electronic Engine Controls for more information.
NOTE :
While performing electrical diagnosis & testing, always refer to the electrical schematics for specific circuit
and component information.
DIAGNOSIS & TESTING
03
Diagnostic Procedure
1.
CHECK EXHAUST GAS LEAK
• Start engine and run it at idle.
• Listen for exhaust gas leak before the three way catalyst.
Is the check result normal?
Yes
>>
Go to the next step.
No
>>
Repair or replace.
2.
CHECK FOR INTAKE AIR LEAK
• Turn ignition switch on.
• Listen for intake air leak after the air flow sensor.
• Check PCV hose connector.
Is the check result normal?
Yes
>>
Go to the next step.
No
>>
Repair or replace.
3.
CHECK ECM CONTROL SIGNAL IN DATA STREAM
• With the X-431, select view data stream.
MONITOR ITEM
CONDITION
DATA
Injector pulse
• Engine: warm up
• Shift: P or N
• Air conditioning: off
• No load
Idle
Approximately 2.5 ms
Is the check result normal?
Yes
>>
Go to step 7.
No
>>
Go to the next step.
4.
CHECK UPSTREAM O
2
SENSOR ELECTRICAL CONNECTOR
• Turn ignition switch off.
• Disconnect the upstream O
2
sensor (1) electrical
connector.
• Inspect the electrical connector for damage.
Is the electrical connector OK?
Yes
>>
Go to the next step.
No
>>
Repair or replace the electrical connector
as necessary.
DIAGNOSIS & TESTING
BESM030017
5.
CHECK UPSTREAM O
2
SENSOR SIGNAL CIRCUIT
• Disconnect ECM harness connector.
• Check harness continuity between the following terminals.
UPSTREAM O
2
SENSOR
ECM TERMINAL
O
2
SENSOR TERMINAL
O
2
sensor 1
36
3
18
4
• Continuity should exist.
• Also check harness for short to ground.
Is the check result normal?
Yes
>>
Go to the next step.
No
>>
Repair or replace circuit for an open or short to ground in harness or connectors.
6.
CHECK AIR FLOW SENSOR SIGNAL
• Check air flow in data stream.
TERMINAL NO.
ITEM
CONDITION
DATA (AVERAGE DC
VOLTAGE)
37
Air flow sensor
• Engine is running
• ECT: 78°C
• Idle: 795 RPM
• IAT: 36°C
• IAT signal: 1.88 V
Approximately 322 kg/h
Approximately 1.39 V
Is the check result normal?
Yes
>>
Go to the next step.
No
>>
Check connectors for rusted terminals or loose connectors in the air flow sensor circuit or ground.
DIAGNOSIS & TESTING
03
7.
CHECK FUEL PRESSURE
• Release fuel pressure to zero.
• Install fuel pressure gauge (2) and check fuel
pressure.
• Observe the following fuel pressures when testing (See Fuel Pressure Test in Section 04 Fuel Delivery).
FUEL PRESSURES
Key On
400 kPa (4.0 bar)
Key Off
380 kPa (3.8 bar) in 10 minutes
Engine Idle 400 kPa (4.0 bar )
- 420 kPa (4.2 bar)
Is the check result normal?
Yes
>>
Go to step 9.
No
>>
Go to the next step.
8.
DETECT MALFUNCTIONING PART
• Check the following:
− Fuel pump and circuit.
− Fuel pressure regulator.
− Fuel lines.
− Fuel filter for clogging.
Is the check result normal?
Yes
>>
If with the X-431, go to the next step.
If without the X-431, go to step 10.
No
>>
Repair or Replace malfunctioning part.
DIAGNOSIS & TESTING
BESM030020
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