Ford F150 Pickup. Instruction - part 1355

Faults in ignition system should set a DTC. If any DTCs are present, perform appropriate system test. See 
DIAGNOSTIC TROUBLE CODE DEFINITIONS in SELF-DIAGNOSTICS - CNG, FLEX-FUEL & 
GASOLINE article. If no DTCs are present, check secondary ignition system. See TEST JB: SECONDARY 
IGNITION under SYSTEM TESTS in SELF-DIAGNOSTICS - CNG, FLEX-FUEL & GASOLINE article. 

EMISSION SYSTEMS & SUB-SYSTEMS 

CATALYTIC CONVERTER 

EMISSIONS COMPLIANCE 

Canada and some states or metropolitan areas in the United States require periodic emission, or 
Inspection/Maintenance (I/M) tests. All Ford products have been designed to pass these tests. If a Ford vehicle 
fails an I/M test, ensure correct model, year, test weight (less than vehicle's GVW) and correct calibration 
(California or Federal) are on the test report. 

Identify which gas readings are high or low and identify in which mode the gas(es) failed. If all gases were high 
at the beginning of the test then decreased, the engine or catalytic converter temperature may not have been at 
operating temperature and stabilized prior to the test, or the vehicle had idled for an excessive period of time 
prior to the test. Perform DIAGNOSTIC ROUTINES after analyzing I/M test report. 

If any emission component is changed, Keep-Alive Memory (KAM) should be cleared and basic adaptive 
strategy should be relearned before repeating state emission test procedure. To clear KAM and perform basic 
adaptive strategy, perform KEEP ALIVE RANDOM ACCESS MEMORY RESET PROCEDURE under 
CLEARING CODES under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - CNG, FLEX-FUEL & 
GASOLINE article. 

Diagnostic Routines 

1) Analyze Vehicle Inspection/Maintenance (I/M) Test Report 
Ensure vehicle Inspection/Maintenance (I/M) test report has been analyzed. Check for data entry errors, 
correct model, year, vehicle test weight and correct calibration (California or Federal). Identify which gas 
readings are HIGH and which were LOW. If report includes a drive trace, identify during which mode the 
gas(es) failed. When report has been analyzed completely, go to next step. 

2) Vehicle Failed EVAP Compliance 
 
If vehicle failed an EVAP Emissions System Leak Test or a Purge Flow Test only, go to step 35) . If 
vehicle failed EVAP, Purge Flow and gas tests, go to next step. 

NOTE:

If vehicle fails emissions test or catalytic converter efficiency is in question, 
perform EMISSIONS COMPLIANCE procedures. See EMISSIONS COMPLIANCE .

NOTE:

If all gases were HIGH early, then decreased, catalyst may not have been 
at proper operating temperature when testing began.

 

2003 Ford Pickup F150 

2003 ENGINE PERFORMANCE System & Component Testing - Gasoline

  

3) Baseline Vehicle 
 
Using an exhaust gas analyzer, baseline vehicle. If vehicle must be driven to achieve baseline, ensure 
baseline drive cycle is able to be repeated to verify the repairs. During baseline, check for any related 
symptoms that may be present (driveability, A/T shifting or exhaust smoke). When vehicle has been 
baselined, go to next step. 

4) Check For Other Symptoms 
 
Check for driveability concerns (including idle and A/T shifting concerns, exhaust smoke and for cooling 
system concerns (engine unable to reach normal operating temperature). If other symptoms are present, 
perform QUICK TEST in SELF-DIAGNOSTICS - CNG, FLEX-FUEL & GASOLINE article. Repair as 
necessary, then go to step 40) to verify repairs. If no other symptoms are present, go to next step. 

5) Preliminary Checks 
 
Check for vacuum leaks or blockage. Check wiring harness connectors. Ensure proper scheduled 
maintenance has been performed. Check intake air tube and air cleaner for obstructions, leaks or dirty 
element. Ensure proper emission controls and components are installed on vehicle. Repair as necessary, 
then go to step 40) to verify repairs. If no repairs are necessary and all checks are okay, go to next step. 

6) Perform PCM Quick Test 
 
Perform QUICK TEST in SELF-DIAGNOSTICS - CNG, FLEX-FUEL & GASOLINE article to retrieve 
Diagnostic Trouble Codes (DTCs). If no DTCs are present, go to next step. If DTCs are present, service 
DTC. See DIAGNOSTIC TROUBLE CODE DEFINITIONS in SELF-DIAGNOSTICS - GASOLINE 
article to service appropriate DTC, then go to step 40) to verify repairs. 

7) Check Carbon Monoxide (CO) Levels 
 
Check vehicle CO levels. If vehicle did not have excessive CO levels, go to next step. If vehicle had 
excessive CO levels, this indicates that engine is running rich. Go to step 15) . 

8) Check Hydrocarbon (HC) Levels 
 
Check vehicle HC levels. If vehicle did not have excessive HC levels, go to next step. If vehicle had 
excessive HC levels with low to normal CO levels, this indicates that engine is running lean. Go to step 
25) . 

9) Check Oxides Of Nitrogen (NOx) Levels 
 
Check vehicle NOx levels. If vehicle did not have excessive NOx levels, verify all previous testing. If 
vehicle had excessive NOx levels, go to step 30) . 

NOTE:

A break in step numbering sequence occurs at this point. Procedure skips 
from step 9) to step 15) . No test procedures have been omitted.

 

2003 Ford Pickup F150 

2003 ENGINE PERFORMANCE System & Component Testing - Gasoline

  

15) High CO Levels: Check HC Levels 
Check vehicle HC levels. If vehicle had excessive HC levels, check for incomplete combustion/running 
rich. Go to next step. If vehicle did not have excessive HC levels, go to step 17) to check for running rich 
concern. 

16) Check Secondary Ignition System 
 
Go to TEST JB: SECONDARY IGNITION , step 1) under SYSTEM TESTS in SELF-DIAGNOSTICS 
- CNG, FLEX-FUEL & GASOLINE article to check secondary ignition system. Follow diagnostic 
procedures and repair as necessary, then go to step 40) to verify repairs. If secondary ignition system is 
okay, go to next step. 

17) Check Fuel Delivery System For High Fuel Pressure Or Leak-Down 
 
Check fuel delivery system. On Natural Gas models, go to TEST HB: NATURAL GAS FUEL 
DELIVERY SYSTEM , step 1) under SYSTEM TESTS in SELF-DIAGNOSTICS - CNG, FLEX-FUEL 
& GASOLINE article. On all other models, go to TEST HC: GASOLINE FUEL DELIVERY 
SYSTEM , step 1) under SYSTEM TESTS in SELF-DIAGNOSTICS - CNG, FLEX-FUEL & 
GASOLINE article. Follow diagnostic procedures and repair as necessary, then go to step 40) to verify 
repairs. If fuel delivery system is okay, go to next step. 

18) Check PCV System 
 
Check PCV system. Go to POSITIVE CRANKCASE VENTILATION . Follow diagnostic procedures 
and repair as necessary, then go to step 40) to verify repairs. If PCV system is okay, go to next step. 

19) Check Exhaust System 
 
Check exhaust system. Go to TEST HF: CATALYST EFFICIENCY MONITOR & EXHAUST 
SYSTEMS , step 1) under SYSTEM TESTS in SELF-DIAGNOSTICS - CNG, FLEX-FUEL & 
GASOLINE article. Follow diagnostic procedures and repair as necessary, then go to step 40) to verify 
repairs. If exhaust system is okay, go to next step. 

20) Check Engine Mechanical Condition 
 
See appropriate article in ENGINES. Check compression, camshaft, valve train components, etc. Repair 
as necessary, then go to step 40) to verify repairs. If no engine mechanical problems are indicated and all 
checks are okay, go to next step. 

21) Additional Checks 
 
Ensure correct PCV valve is installed for application. Service as necessary, then go to step 40) to verify 
repairs. If PCV valve is correct, go to step 45) . 

NOTE:

A break in step numbering sequence occurs at this point. Procedure skips 
from step 21) to step 25) . No test procedures have been omitted.

 

2003 Ford Pickup F150 

2003 ENGINE PERFORMANCE System & Component Testing - Gasoline

  

25) High HC With Normal To Low CO Level, Check Fuel Delivery System For Leak-Down Or Low 
Fuel Pressure 
Check fuel delivery system for leak-down or low pressure. On Natural Gas models, go to TEST HB: 
NATURAL GAS FUEL DELIVERY SYSTEM , step 1) under SYSTEM TESTS in SELF-
DIAGNOSTICS - CNG, FLEX-FUEL & GASOLINE article. On all other models, go to TEST HC: 
GASOLINE FUEL DELIVERY SYSTEM , step 1) under SYSTEM TESTS in SELF-DIAGNOSTICS 
- CNG, FLEX-FUEL & GASOLINE article. Follow diagnostic procedures and repair as necessary, then 
go to step 40) to verify repairs. If fuel delivery system is okay, go to next step. 

26) Check Secondary Ignition System 
 
Go to TEST JB: SECONDARY IGNITION , step 1) under SYSTEM TESTS in SELF-DIAGNOSTICS 
- CNG, FLEX-FUEL & GASOLINE article to check secondary ignition system. Follow diagnostic 
procedures and repair as necessary, then go to step 40) to verify repairs. If secondary ignition system is 
okay, go to next step. 

27) Check PCV System 
 
Go to POSITIVE CRANKCASE VENTILATION to check PCV system. Follow diagnostic procedures 
and repair as necessary, then go to step 40) to verify repairs. If PCV system is okay, go to next step. 

28) Check Engine Mechanical Condition 
 
See appropriate article in ENGINES. Check compression, camshaft, valve train components, etc. Repair 
as necessary, then go to step 40) to verify repairs. If no engine mechanical problems are indicated and all 
checks are okay, go to next step 

29) Additional Checks 
 
Ensure correct PCV valve is installed for application. Service as necessary, then go to step 40) to verify 
repairs. If PCV valve is correct, go to step 45) . 

30) High NOx With Normal To Low HC & CO Levels 
 
Check engine for concerns such as excessive carbon build-up in combustion chamber. See appropriate 
article in ENGINES. Repair as necessary, then go to step 40) to verify repairs. If no engine mechanical 
problems are indicated, go to next step. 

31) Additional Checks 
 
Check Torque Converter Clutch (TCC) operation. See appropriate OVERHAUL or DIAGNOSIS article 
in AUTOMATIC TRANSMISSIONS. Check intake air system for add-on aftermarket parts or 
modifications which may restrict airflow into intake air system. Check for running lean concerns (vacuum 
leaks or low fuel pressure), refer to procedures starting at step 25) . Repair as necessary, then go to step 
40) to verify repairs. If all checks are okay, go to step 45) . 

NOTE:

A break in step numbering sequence occurs at this point. Procedure skips 

 

2003 Ford Pickup F150 

2003 ENGINE PERFORMANCE System & Component Testing - Gasoline