Ford F150 Pickup. Instruction - part 1281

Fig. 20: Locating Vaporizer Retaining Bolts 
Courtesy of FORD MOTOR CO. 

ADJUSTMENTS 

FUEL RAIL (TUNABLE "T") 

1. Park vehicle on flat surface, set parking brake and place wheel chocks both in front of and behind front 

wheels. Turn ignition switch to OFF position. Place ALT/GAS switch to ALT position. Connect a 
vacuum gauge to intake manifold vacuum.  

2. Connect New Generation Star (NGS) Tester (418-F048), to vehicle Data Link Connector (DLC). Turn the 

ignition switch to ON position. Select, monitor, and record Powertrain Control Module (PCM) PIDs; 
ECT, O2S1/1 and O2S2/1. Start and run engine while monitoring ECT PID. Allow engine to warm up 
until ECT PID reads 190°F (88°C). 

3. Select, monitor, and record Alternate Fuel Control Module (AFCM) MAP PID and engine vacuum. Place 

transmission in Reverse while applying brake pedal then slowly apply pressure to accelerator pedal. 

WARNING:

The following step requires engine to be running, in gear and at high 
RPM. Ensure parking brake is fully set and wheels are chocked. Use 
all necessary precautions to avoid personal injury, or property 
and/or equipment damage.

 

2003 Ford Pickup F150 

2003 ENGINE PERFORMANCE Removal & Installation - F150 Pickup - Bi-Fuel - Gasoline/LPG

  

Continue to raise engine RPM until AFCM MAP PID reads 7.3-7.4 psi (.5 kg/cm

2

 ) and record engine 

vacuum. Vacuum value will be used in the remaining procedures as "Tuning Point". Allow engine to 
return to idle position and place transmission in Park. 

4. Locate 2 adjustment screw holes on top of tuning "T" assembly, remove any sealant and access 

adjustment screws. See Fig. 21 . Using a screwdriver, position both tuning "T" adjustment screws to their 
"Neutral" position by turning screws until screw head tops are flush with top of tuning "T" and then 
turning them clockwise 2 complete turns.  

5. With engine running at idle speed and transmission in Park, select GRAPH on NGS scan tool. Record 10 

seconds of data from PCM PIDs O2S1/1 and O2S2/1. Retrieve and record signal data and identify which 
HO2S signal displays longest "High State Time". See Fig. 22 . 

6. Use an assistant seated in driver seat, and repeat steps 3 and 4 . Obtain and hold "Tuning Point" vacuum 

value. Select GRAPH on NGS and record 10 seconds of data from PCM PIDs O2S1/1 and O2S2/1. 
Allow engine to return to idle, and place transmission in Park. Retrieve and record signal data and 
identify which HO2S signal displays longest "High State Time" as in step 5 . See Fig. 22 .  

7. Determine which tuning "T" adjustment screw requires adjustment. This screw is the only screw to be 

adjusted throughout entire tuning "T" adjusting procedure and is determined by the following: 

z

PCM PID O2S1/1 data reflects upstream bank No. 1 HO2S and is adjusted with passenger's side 
tuning "T" adjustment screw.  

z

PCM PID O2S2/1 data reflects upstream bank No. 2 HO2S and is adjusted with driver's side tuning 
"T" adjustment screw.  

To reduce PCM PID O2S1/1 or O2S2/1 "High State Time", corresponding tuning "T" adjustment screw is 
turned clockwise. To increase PCM PID O2S1/1 or O2S2/1 "High State Time", tuning "T" adjustment 
screw is turned counterclockwise. 

8. Turn tuning "T" adjustment screw identified in step 6 , one complete turn clockwise (reducing "High 

State Time") and repeat steps 5 and 6 . Retrieve and compare current graphed PCM PIDs O2S1/1 and 
O2S2/1 data with previous data.  

9. If PCM HO2S PID from previous graphed data continues to have longer "High State Time", repeat step 

8 . If PCM HO2S PID from previous graphed data now has a shorter "High State Time", turn 
corresponding tuning "T" adjustment screw counterclockwise 1/2 turn and repeat steps 5 and 6 .  

10. Retrieve and compare current recorded graphed PCM PIDs O2S1/1 and O2S2/1 data. If necessary, 

continue to turn same adjustment screw by 1/4 and 1/8 turn increments, clockwise or counterclockwise as 

WARNING:

Never remove tuning "T" adjustment screws while low pressure fuel 
lines are pressurized. Use caution when setting adjustment screws. 
If adjustment screws become dislodged from tuning "T", serious 
personal injury may result.

WARNING:

The following step requires 2 people. Engine needs to be running in 
gear, and engine RPM raised. Ensure parking brake is fully set and 
wheels are chocked. Take all necessary precautions to avoid 
personal injury, property and/or equipment damage.

 

2003 Ford Pickup F150 

2003 ENGINE PERFORMANCE Removal & Installation - F150 Pickup - Bi-Fuel - Gasoline/LPG

  

described in step 7 repeating steps 5 and 6 with each adjustment until both HO2S PIDs display equal 
"High State Time". See Fig. 23 .  

11. When retrieved PCM PIDs O2S1/1 and O2S2/1 display equal "High State Time", alternate fuel system is 

correctly tuned and no further adjustment is required. Document following information: 

z

VIN, date, lead technician and assistant.  

z

HO2S bank number adjusted, required number of turns to adjustment screw (to nearest 1/8th turn).  

Turn ignition switch to OFF position and remove vacuum gauge and restore intake vacuum system to 
normal operating condition. 

12. Paint mark tuning "T" adjustment screw positions and seal access hole with manufacturer's sensor safe 

sealant. Cover and label adjustment screw cavities indicating alternate fuel system tuning procedure has 
been performed. Update all necessary vehicle inspection labels and placards.  

Fig. 21: Identifying Tuning "T" Adjustment Screws 
Courtesy of FORD MOTOR CO. 

 

2003 Ford Pickup F150 

2003 ENGINE PERFORMANCE Removal & Installation - F150 Pickup - Bi-Fuel - Gasoline/LPG

  

Fig. 22: Identifying HO2S "High State Time" Signal (Example) 
Courtesy of FORD MOTOR CO. 

Fig. 23: Identifying Normal HO2S "High State Time" Signal (Example)

 

2003 Ford Pickup F150 

2003 ENGINE PERFORMANCE Removal & Installation - F150 Pickup - Bi-Fuel - Gasoline/LPG