CATALYST & EXHAUST SYSTEMS
EMISSION SYSTEMS & SUB-SYSTEMS
Since bi-fuel vehicles can operate on gasoline, they have the same emissions equipment as gasoline fueled
vehicles. See THEORY & OPERATION - CNG, FLEX-FUEL & GASOLINE article.
SELF-DIAGNOSTIC SYSTEMS
MALFUNCTION INDICATOR LIGHT
Alternative fuel diagnostics are automatic, active and continuous monitors of the bi-fuel system while the
vehicle is operating in Compressed Natural Gas (CNG) mode. The system monitors the activity of various
sensor inputs and compares the values to calibrated reference criteria. If a signal does not satisfy the reference
criteria, a fault code is generated and stored. If the fault is of an emissions-critical nature, the system will
illuminate the Malfunction Indicator Lamp (MIL) and the ALT fuel selector switch indicator will change from a
steady on to an irregular flashing condition. If the fault condition stops, the MIL will return to normal status
after three trips and the fault code is stored in continuous memory for access during diagnostic procedures. If
the fault condition does not occur for forty trips, the fault code is erased.
MISCELLANEOUS CONTROLS
A/C SYSTEM
A/C Cycling Switch, A/C Evaporator Temperature Sensor, A/C High Pressure Switch & A/C Pressure Sensor
For additional information, see INPUT DEVICES under COMPUTERIZED ENGINE CONTROLS in
THEORY & OPERATION - CNG, FLEX-FUEL & GASOLINE article.
TRANSMISSION
Electronically Controlled Transmission & Torque Converter Clutch
NOTE:
Since bi-fuel vehicles can operate on gasoline, they have the same catalyst and
exhaust equipment as gasoline fueled vehicles. For additional information not
contained in this article, see CATALYST & EXHAUST SYSTEMS in THEORY &
OPERATION - CNG, FLEX-FUEL & GASOLINE article.
NOTE:
Both gasoline and bi-fuel systems have self-diagnostic capabilities. For
information on procedures for entering self-test modes and reading DTCs, see
SELF-DIAGNOSTICS - CNG, FLEX-FUEL & GASOLINE or SELF-DIAGNOSTICS -
BI-FUEL - GASOLINE/CNG article.
NOTE:
Although not considered true engine performance-related systems, some
controlled devices may affect driveability if they malfunction.
2003 Ford Pickup F150
2003 ENGINE PERFORMANCE Theory & Operation - Bi-Fuel - Gasoline/CNG