Ford F150 Pickup. Instruction - part 1605

z

Check fuel system. See TEST AA: NO START - GASOLINE MODE under SYSTEM TESTS in 
SELF-DIAGNOSTICS - BI-FUEL - GASOLINE/LPG article.  

z

If engine is still a no-start after completing previous test, see TEST KE: IDLE AIR CONTROL 
VALVE under SYSTEM TESTS in SELF-DIAGNOSTICS - CNG, FLEX-FUEL & GASOLINE article. 

z

Check exhaust system for restriction. See TEST HF: CATALYST EFFICIENCY MONITOR & 
EXHAUST SYSTEMS under SYSTEM TESTS in SELF-DIAGNOSTICS - CNG, FLEX-FUEL & 
GASOLINE article.  

z

Check engine mechanical condition. Check compression, camshaft, valve train components, etc. and 
repair as necessary. See appropriate article in ENGINES. If no problem is found, check for intermittent 
faults. See TEST Z: INTERMITTENT under SYSTEM TESTS in SELF-DIAGNOSTICS - CNG, 
FLEX-FUEL & GASOLINE article.  

SLOW RETURN TO IDLE 

z

Check vacuum hoses, lines and throttle body for vacuum leaks.  

z

Check fuel delivery system. See TEST HC: FUEL DELIVERY SYSTEM under SYSTEM TESTS in 
SELF-DIAGNOSTICS - BI-FUEL - GASOLINE/LPG article.  

z

Check air intake system. See TEST HU: AIR INTAKE SYSTEM under SYSTEM TESTS in SELF-
DIAGNOSTICS - CNG, FLEX-FUEL & GASOLINE article.  

z

Check PCV system. See TEST HG: PCV SYSTEM under SYSTEM TESTS in SELF-DIAGNOSTICS -
CNG, FLEX-FUEL & GASOLINE article.  

z

If no concern is found, check for intermittent faults. See TEST Z: INTERMITTENT under SYSTEM 
TESTS in SELF-DIAGNOSTICS - CNG, FLEX-FUEL & GASOLINE article.  

FAST IDLE (DIESELS/RUNS ON) 

z

Check base engine for air leaks, including proper sealing of intake manifold and components attached to 
intake air; such as EGR valve or IAC valve.  

z

Check air intake system. See TEST HU: AIR INTAKE SYSTEM under SYSTEM TESTS in SELF-
DIAGNOSTICS - CNG, FLEX-FUEL & GASOLINE article.  

z

Check cooling system for overheating. If cooling system is overheating, repair as necessary. See 
appropriate ELECTRIC COOLING FANS article in ENGINE COOLING.  

z

Check A/C system. See appropriate AUTOMATIC or MANUAL A/C-HEATER SYSTEMS article in 
AIR CONDITIONING & HEATING.  

z

For a fast idle concern, turn ignition off. Connect scan tool to Data Link Connector (DLC). Turn ignition 

CAUTION: Extended cranking, due to a no-start condition, can load exhaust system 

with raw fuel, which may ruin catalytic converter after engine is started.

NOTE:

If vehicle runs normally after ignition is off, check for damaged ignition switch, 
IGN RUN circuit shorted to power and/or VPWR circuit shorted to power. See 
ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in 
ELECTRICAL.

 

2003 Ford Pickup F150 

2003 ENGINE PERFORMANCE Trouble Shooting - No Codes - Bi-Fuel - Gasoline/LPG

  

on. Using scan tool, access PCM and select TP MODE PID from PID/DATA MONITOR & RECORD 
menu. Monitor TP MODE PID while wiggling TP sensor circuits. With throttle closed, TP MODE PID 
should read C/T (closed throttle). If TP MODE PID is not C/T with throttle closed, select and monitor TP 
V and TPREL PIDs for sudden changes while wiggling TP sensor circuits. At vehicle start, TPREL PID 
reading will begin at about 1.25 volts and count down to lowest TP V value since engine start-up. If TP V 
value goes below normal range, then increases again, TPREL will set to lower voltage. If TP V is 
about .04 volt more than TPREL value at closed throttle, PCM will go into part throttle mode. Also check 
for loose or worn throttle plates. If no problem is found, check for intermittent faults. Go to TEST Z: 
INTERMITTENT under SYSTEM TESTS in SELF-DIAGNOSTICS - CNG, FLEX-FUEL & 
GASOLINE article.  

LOW IDLE (STALLS ON DECELERATION) 

z

Check air intake system. See TEST HU: AIR INTAKE SYSTEM under SYSTEM TESTS in SELF-
DIAGNOSTICS - CNG, FLEX-FUEL & GASOLINE article.  

z

Check fuel delivery system. See TEST HC: FUEL DELIVERY SYSTEM under SYSTEM TESTS in 
SELF-DIAGNOSTICS - BI-FUEL - GASOLINE/LPG article.  

z

Check A/T Torque Converter Clutch (TCC) system. See appropriate DIAGNOSIS article in 
AUTOMATIC TRANSMISSIONS.  

BACKFIRES 

z

Check secondary ignition system. See TEST JB: SECONDARY IGNITION under SYSTEM TESTS in 
SELF-DIAGNOSTICS - CNG, FLEX-FUEL & GASOLINE article.  

z

Check fuel delivery system. See TEST HC: FUEL DELIVERY SYSTEM under SYSTEM TESTS in 
SELF-DIAGNOSTICS - BI-FUEL - GASOLINE/LPG article.  

z

Check engine mechanical condition. Check compression, camshaft, valve train components, etc., and 
repair as necessary. See appropriate article in ENGINES.  

z

Check exhaust system for restriction. See TEST HF: CATALYST EFFICIENCY MONITOR & 
EXHAUST SYSTEMS under SYSTEM TESTS in SELF-DIAGNOSTICS - CNG, FLEX-FUEL & 
GASOLINE article.  

LACK/LOSS OF POWER 

z

Check air intake system. See TEST HU: AIR INTAKE SYSTEM under SYSTEM TESTS in SELF-
DIAGNOSTICS - CNG, FLEX-FUEL & GASOLINE article.  

z

Check secondary ignition system. See TEST JB: SECONDARY IGNITION under SYSTEM TESTS in 

NOTE:

The PCM is equipped with an over RPM/speed limit function. If programmed 
speed is exceeded, fuel delivery will shut off and DTC P1270 will be set in PCM 
memory. If vehicle is equipped with a Knock Sensor (KS), a lack of power may 
result when vehicle is operated with a breakout box installed at PCM. KS 
circuits are not shielded in breakout box, and KS signal noise may be noticed 
by PCM. If this happens, spark timing will be retarded and a lack of power may 
result.

 

2003 Ford Pickup F150 

2003 ENGINE PERFORMANCE Trouble Shooting - No Codes - Bi-Fuel - Gasoline/LPG

  

SELF-DIAGNOSTICS - CNG, FLEX-FUEL & GASOLINE article. 

z

Check fuel delivery system. See TEST HC: FUEL DELIVERY SYSTEM under SYSTEM TESTS in 
SELF-DIAGNOSTICS - BI-FUEL - GASOLINE/LPG article.  

z

Check exhaust system for restriction. See TEST HF: CATALYST EFFICIENCY MONITOR & 
EXHAUST SYSTEMS under SYSTEM TESTS in SELF-DIAGNOSTICS - CNG, FLEX-FUEL & 
GASOLINE article.  

z

Check EGR system. See TEST HE: EGR SYSTEM under SYSTEM TESTS in SELF-DIAGNOSTICS 
- CNG, FLEX-FUEL & GASOLINE article.  

z

Check engine mechanical condition. Check compression, camshaft, valve train components, etc., and 
repair as necessary. See appropriate article in ENGINES.  

z

On A/T models, check ATF level, throttle linkage and A/T Torque Converter Clutch (TCC) solenoid or 
circuits. See appropriate DIAGNOSIS article in AUTOMATIC TRANSMISSIONS.  

z

Check for dragging brakes and repair as necessary. See appropriate DISC & DRUM article in BRAKES.  

z

Connect scan tool to Data Link Connector (DLC). Turn ignition on. Using scan tool, access PCM and 
select DPFEGR (if equipped), LONGFT1 and LONGFT2 PIDs from PID/DATA MONITOR & 
RECORD menu. See PIN VOLTAGE CHARTS - GASOLINE/LPG article. DPFEGR PID value 
should be within .15 volt of Key On Engine Off (KOEO) value. If LONGFT1 or LONGFT2 PID value is 
low (-20 percent), concentrate checks in areas that would cause engine to run rich. If LONGFT1 or 
LONGFT2 PID value is high (+20 percent), concentrate checks in areas that would cause engine to run 
lean.  

z

Check Mass Air Flow (MAF) sensor and related circuits. See TEST DC: MASS AIRFLOW SENSOR 
under SYSTEM TESTS in SELF-DIAGNOSTICS - CNG, FLEX-FUEL & GASOLINE article. 

z

Additional Checks 
 
Check customer driving habits. Check for correct PCM Vehicle Identification (VID) block information. 
See FLASH VEHICLE IDENTIFICATION BLOCK PROCEDURE under PROGRAMMING PCM 
in SELF-DIAGNOSTICS - CNG, FLEX-FUEL & GASOLINE article. Check charging system. See 
appropriate GENERATORS & REGULATORS article in ELECTRICAL. Ensure engine RPM/speed 
limiting functions of PCM are operating properly. Check for incorrect high vehicle speed signal. If no 
problems are indicated, return to SYMPTOM DIAGNOSIS to identify any additional symptoms or 
check for intermittent faults. See TEST Z: INTERMITTENT under SYSTEM TESTS in SELF-
DIAGNOSTICS - CNG, FLEX-FUEL & GASOLINE article.  

SPARK KNOCK 

z

Check cooling system for overheating. If cooling system is overheating, repair as necessary. See 
appropriate ELECTRIC COOLING FANS article in ENGINE COOLING.  

z

Check engine mechanical condition. Check compression, camshaft, valve train components, etc. and 
repair as necessary. See appropriate article in ENGINES. 

NOTE:

If the following tests fail to correct spark knock concern, it is recommended that 
owner changes source of fuel. For CNG models, ensure proper grade of fuel is 
being used.

 

2003 Ford Pickup F150 

2003 ENGINE PERFORMANCE Trouble Shooting - No Codes - Bi-Fuel - Gasoline/LPG

  

z

Check fuel delivery system. See TEST HC: FUEL DELIVERY SYSTEM under SYSTEM TESTS in 
SELF-DIAGNOSTICS - BI-FUEL - GASOLINE/LPG article.  

z

Check secondary ignition system. See TEST JB: SECONDARY IGNITION under SYSTEM TESTS in 
SELF-DIAGNOSTICS - CNG, FLEX-FUEL & GASOLINE article.  

z

Check Knock Sensor (KS). See TEST DG: KNOCK SENSOR under SYSTEM TESTS in SELF-
DIAGNOSTICS - CNG, FLEX-FUEL & GASOLINE article.  

z

Check PCV system. See TEST HG: PCV SYSTEM under SYSTEM TESTS in SELF-DIAGNOSTICS -
CNG, FLEX-FUEL & GASOLINE article.  

z

Visually inspect engine oil quality. Replace if necessary.  

z

Check Mass Air Flow (MAF) sensor and related circuits. See TEST DC: MASS AIRFLOW SENSOR 
under SYSTEM TESTS in SELF-DIAGNOSTICS - CNG, FLEX-FUEL & GASOLINE article.  

POOR FUEL ECONOMY 

z

Connect scan tool to Data Link Connector (DLC). Turn ignition on. Using scan tool, access PCM and 
select DPFEGR (if equipped), LONGFT1, LONGFT2 and VPWR PIDs from PID/DATA MONITOR & 
RECORD menu. See PIN VOLTAGE CHARTS - GASOLINE/LPG article. DPFEGR PID value 
should be within .15 volt of Key On Engine Off (KOEO) value. If DPFEGR PID value is not as specified, 
check EGR. See TEST HE: EGR SYSTEM , step 100) under SYSTEM TESTS in SELF-
DIAGNOSTICS - CNG, FLEX-FUEL & GASOLINE article. If LONGFT1 or LONGFT2 PID value is 
low (-20 percent), concentrate checks in areas that would cause engine to run rich. If LONGFT1 or 
LONGFT2 PID value is high (+20 percent), concentrate checks in areas that would cause engine to run 
lean. If VPWR PID voltage is not 10.5-17.0 volts, check charging system. See appropriate 
GENERATORS & REGULATORS article in ELECTRICAL. If VPWR PID voltage is 10.5-17.0 volts 
but not within .5 volt of battery voltage, check battery supply to PCM power relay. Check VPWR circuit 
between PCM and PCM power relay, and PWR GND circuits to PCM. See ENGINE PERFORMANCE 
in SYSTEM WIRING DIAGRAMS article in ELECTRICAL.  

z

Check A/T Torque Converter Clutch (TCC) and/or TCC solenoid for proper operation. See appropriate 
DIAGNOSIS article in AUTOMATIC TRANSMISSIONS.  

z

Check PCV system. See TEST HG: PCV SYSTEM under SYSTEM TESTS in SELF-DIAGNOSTICS -
CNG, FLEX-FUEL & GASOLINE article.  

z

Check for correct PCM Vehicle Identification (VID) block information. See FLASH VEHICLE 
IDENTIFICATION BLOCK PROCEDURE under PROGRAMMING PCM in SELF-DIAGNOSTICS 
- CNG, FLEX-FUEL & GASOLINE article. Check for dragging brakes and repair as necessary. See 
appropriate DISC & DRUM article in BRAKES. Visually inspect Mass Air Flow (MAF) sensor for 
contamination.  

z

Check cooling system for overheating. If cooling system is overheating, repair as necessary. See 
appropriate ELECTRIC COOLING FANS article in ENGINE COOLING. 

NOTE:

Fuel consumption can be increased during stop-and-go driving, trailer towing, 
short-run operation, extended winter warm-up periods, improper tire inflation, 
high speed driving, improper axle ratio and aftermarket add-ons. Determine if 
these factors are the cause of poor fuel mileage before proceeding with 
diagnostic procedure.

 

2003 Ford Pickup F150 

2003 ENGINE PERFORMANCE Trouble Shooting - No Codes - Bi-Fuel - Gasoline/LPG