Lotus 2004 ELISE Service Notes page 143

Lotus Service Notes
Fuel Control System Too Lean Or Rich
P0171 System Too Lean
P0172 System Too Rich
Description
The oxygen sensor sends a signal to the ECU corresponding to the exhaust gas oxygen content enabling the
ECU to maintain a 14.7:1 air/fuel ratio under normal driving conditions. The ECU can make fuel corrections
of ± 17% to the calculated fuel demand. If the ECU determines a rich condition exists (oxygen sensor above
0.450mV), it will decrease the calculated fuel demand to maintain a 14.7:1 ratio. If the ECU determines a lean
condition exists (oxygen sensor below 0.450mV), it will increase the calculated fuel demand to maintain a
14.7:1 ratio.
Enable Criteria
• Fuel Trim condition enabled
• Closed loop fuelling enabled
• Engine speed > 1100 rpm
• MAF > 6 g/sec
• Engine load < 70 %
• Altitude < 8000 ft (2438 m), Baro > 756 mbar
• Inlet air temperature > -10°C (14°F)
Disable Criteria
P0106, P0107, P0108
P0111, P0112, P0113
P0131, P0132, P0133, P0134, P0135
P0300, P0301, P0302, P0303, P0304
P0441, P0442, P0443, P0447, P0448, P0450, P0451, P0455, P0456 – EVAP faults
Monitor: Continuous
Malfunction Criteria
P0171
This code is set when the calculated fuel demand has been increased to its maximum limit of 17% and the
system still cannot maintain an air/fuel ratio of 14.7:1 under normal driving conditions.
Potential failure modes:
• Fuel Pressure too low
• Air leak in system
• Water in fuel
• Exhaust leak / crack before front oxygen sensor
• Injector fault
• Sensor connector and wiring for signs of corrosion or loose connections
P0172
This code is set when the calculated fuel demand has been decreased to its minimum limit of -17% and the
system still cannot maintain an air/fuel ratio of 14.7:1 under normal driving conditions.
Potential failure modes:
• Fuel Pressure too high
• Leaking fuel injector
• Restriction in the exhaust system or air intake / filter
• Erratic throttle position sensor
Notes:
• The MIL will be illuminated if the fault is present for 2 consecutive trips.
• Further information on the sensor may be found inToyota 1ZZ-FE, 2ZZ-GE manual RM733E (B120T0327J)
pages DI-67 to DI-72
Page 20
sn_emp_cyclone.indd 20
P0171
P0172
– Baro sensor faults
– Air Intake Sensor faults
– Oxygen sensor faults
– Misfire faults
Section EMP
03/03/2006 11:03:36