Page 161 of 363
The pinking sensor should give a signal which is variable and not zero, to prove that it is recording the
mechanical vibrations of the engine.
If the signal is zero:
- Check the sensor is correctly screwed in.
- Check the insulation and continuity of the wiring:
Computer 1 2 Pinking sensor
Computer 15 1 Pinking sensor
Computer 16 Pinking sensor screening
If necessary, replace the sensor.
JSA051.0
INJECTION
Fault finding - Status and parameter interpretation17
D7F 710
engine -
35 tracks
AFTER REPAIRStart the status and parameter check again from the beginning.
DIAG 8
Fiche n° 27
ANTI-PINKING CIRCUIT
XR25 aid:# 13 is not zero and variable for fast idle or under load
No fault bargraphs should be illuminated.NOTES
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Page 162 of 363

Check the insulation, continuity and that there is no interference resistance
on the line:
Computer 5 C Pressure sensor
Computer 15 A Pressure sensor
Computer 23 B Pressure sensor
Repair if necessary.
JSA052.0
INJECTION
Fault finding - Status and parameter interpretation17
D7F 710
engine -
35 tracks
AFTER REPAIRStart the status and parameter check again from the beginning.
DIAG 9
Fiche n° 27
PRESSURE CIRCUIT
XR25 aid:Ignition on # 01 not coherent
At idle speed # 01 < Minimum or # 01 > Maximum
# 16 not coherent
No fault bargraphs should be illuminated.NOTES
# 01 not coherent
ignition on
# 01 < Minimum at idle
speed
# 16 not coherent
If all these points are correct, replace the sensor.
A vacuum pump with a pressure gauge may be used to check coherence with
# 01 and to show a faulty sensor.
# 01 > Maximum at idle
speedThe manifold pressure is often a sign of incorrect engine operation. Check
- the sealing of the pipe between the manifold and the sensor,
- the valve clearances,
- the canister bleed valve which should be closed at idle speed,
- cylinder compression using the OPTIMA 5800 station.
If all these points are correct, replace the sensor.
A vacuum pump with a pressure gauge may be used to check coherence with
# 01 and to show a faulty sensor.
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Page 163 of 363
JSA051.0
INJECTION
Fault finding - Status and parameter interpretation17
D7F 710
engine -
35 tracks
AFTER REPAIRStart the status and parameter check again from the beginning.
DIAG 10
Fiche n° 27
RICHNESS REGULATION
XR25 aid:Richness regulation faulty
No fault bargraphs should be illuminated.
Ignition correct (a check may be made using the OPTIMA 5800 station).
No other status bargraph should show a fault.
NOTES
Check the sealing of the canister bleed valve (a leak can disrupt the richness considerably).
Check the sealing of the exhaust pipe upstream from the oxygen sensor.
Check the sealing of the inlet manifold.
If the vehicle has only been driven in town, the sensor is contaminated (try driving under load).
Check the fuel pressure.
If the idle speed is unstable, check the valve clearances.
Check the injectors (flow and shape of the jet).
If necessary, replace the oxygen sensor.
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Page 166 of 363
if the value read is incoherent:
- Check that the sensor is correctly mounted and supplied:
•+12 V on A1
• Earth on B2
- Check the insulation, continuity and that there is no interference resistance on the line:
Computer 8 B1 vehicle speed sensor
Repair.
JSA051.0
INJECTION
Fault finding - Status and parameter interpretation17
D7F 710
engine -
35 tracks
AFTER REPAIRStart the status and parameter check again from the beginning.
DIAG 13
Fiche n° 27
VEHICLE SPEED
XR25 aid:# 18 = Speed read on speedometer in km/h
No fault bargraphs should be illuminated.
Check on a road test.NOTES
The fault persists! Replace the speed sensor.
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Page 168 of 363
JSA051.0
INJECTION
Fault finding - Status and parameter interpretation17
D7F 710
engine -
35 tracks
AFTER REPAIRStart the status and parameter check again from the beginning.
NOTES
DIAG 15
Fiche n° 27
EMISSION OF POLLUTANTS
XR25 aid:None
No fault bargraphs should be illuminated.NOTES
0.97 ≤ λ ≤ 1.03 at 2500
rpmThe oxygen sensor loops correctly at 2500 rpm.
If CO > 0.3 % at 2500 rpm
NOTES 0.97 ≤ λ ≤ 1.03
at 2500 rpmThe oxygen sensor does not loop correctly at 2500 rpm.
There is a fault with the injection or the sensor.
The catalytic converter is faulty.
NOTE : it is vital to determine the cause of the catalytic converter damage to
avoid a new converter also being damaged.
If λ < 0.97 or λ > 1.03 at idle speed
Check the sensor earth and heating.
Check there is no air leak at the manifold.
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Page 169 of 363
JSA051.0
INJECTION
Fault finding - Status and parameter interpretation17
D7F 710
engine -
35 tracks
AFTER REPAIRStart the status and parameter check again from the beginning.
DIAG 15
CONT
Fiche n° 27
No fault bargraphs should be illuminated.NOTES
NOTES λ > 1.03
at 2500 rpmNone
The oxygen sensor loops correctly at 2500 rpm.
NOTES λ < 0.97
at 2500 rpm.The oxygen sensor does not loop correctly at 2500 rpm., CO >
0.3 % at 2500 rpm.
Check the pressure sensor.
Check the sensor.
Check that an injector is not faulty.
Check there is no leak at the exhaust.
Check that an injector has not seized.
Check the fuel pressure is not too low.
The oxygen sensor does not loop correctly at 2500 rpm.
Check there is not an injection fault.
Check there is not an ignition fault.
Check the sensor is not faulty.
Check the fuel pressure.
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Page 179 of 363
JSA051.0
INJECTION
Fault finding -Aid
17
D7F 710
engine -
35 tracks
For further details, refer to section 12
Injector resistance = 14.5 Ω
Idle regulation stepping
motor resistance : A - D= 100 Ω
B - C = 100 Ω
Canister bleed valve resistance = 35 Ω
Ignition coil resistance : Primary = 1-4 ; 1-3 ; 2-3 ; 2-4 = 1.5 Ω
3-4 = 0.6 Ω
Secondary = 8 kΩ
Oxygen sensor heating resistance = 3 to 15 Ω
Throttle potentiometer resistance : no load A-B = 1300 Ωfull load A-B = 1300 Ω
A-C = 1360 ΩA-C= 2350 Ω
B-C = 2300 ΩB-C = 1260 Ω
Flywheel signal resistance = 220 Ω
Fuel pressure = 3 bars ignition on/ 2.5 bars at idle speed
Value for: CO = 0.3 % maximum
HC = 100 ppm maximum
CO2 = 14.5 % minimum
Lambda = 0.97 < λ < 1.03
Sensor resistance
Temperature in °C 0 20 40 80 90
Air temperature sensor
Resistance in ohms5000
to
70001700
to
3300500
to
1550--
Coolant temperature sensor
Resistance in ohms6700
to
80002600
to
30001100
to
1300270
to
300200
to
215
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Page 182 of 363
JSA051.0
INJECTION
Fault finding - Checking conformity
17
D7F 710
engine -
35 tracks
Engine cold, ignition on.NOTES
Order of
operationsFunction to be
checkedAction Bargraph Display and notes
6 Throttle position
potentiometerNo load
# 17
Accelerator
pedal slightly
depressed
Full load
# 17 10 < X < 50
185 < X < 245
7Absolute pressure
sensor# 01
X = Local atmospheric pressure
8Coolant temperature
sensor# 02 X = Ambient temperature
± 5 °C
9Air temperature
sensor# 03 X = Ambient temperature
± 5 °C
10
Idle speed regulation
stepping motor# 12The value read is variable
depending on the coolant
temperature :
11 % ≤ X ≤ 100 %
11Engine speed
# 06 X = 0 rpm
12
Canister bleed# 23 X = 0.7 %
2
2
2
17-137