poor run 2005 v10

[techrowe]

2005 F450 6.8 v-10 extremely poor run no throttle response both o2's stuck at 1 volt very rich condition intermittenly.Have cleaned the MAF and throttle body.Fuel trim readings surprise me because short term is not very active and I would expect it to be pegged at -25%.when engine is acting up noticed that the fuel pressure sensor reads 0psi.Have swapped with like truck and same thing happens asb well as other truck ran fine with suspect sensor and read presssure.when running fine pressure reads good on scan tool from sensor.
Assuming that ford uses this data as major input and is going full rich with thought there is no PSI. mechanical gauge reads ok even when acting up so pcm is getting false signal somehow.Noticed that some other sensors share common signal wondering if anyone has seen this possibly another sensor bad and pulling signal volts away causing false readings from fuel pressur sensor.Possible common corrosion point in harness(upstate ny heavy salt)Any ideas appreciated thanks in advance.

 

[blacksnapon]

2005 F450 6.8 v-10 extremely poor run no throttle response both o2's stuck at 1 volt very rich condition intermittenly.Have cleaned the MAF and throttle body.Fuel trim readings surprise me because short term is not very active and I would expect it to be pegged at -25%.when engine is acting up noticed that the fuel pressure sensor reads 0psi.Have swapped with like truck and same thing happens asb well as other truck ran fine with suspect sensor and read presssure.when running fine pressure reads good on scan tool from sensor.
Assuming that ford uses this data as major input and is going full rich with thought there is no PSI. mechanical gauge reads ok even when acting up so pcm is getting false signal somehow.Noticed that some other sensors share common signal wondering if anyone has seen this possibly another sensor bad and pulling signal volts away causing false readings from fuel pressur sensor.Possible common corrosion point in harness(upstate ny heavy salt)Any ideas appreciated thanks in advance.

What does your coolant temp sensors read? If the pcm "sees" that the engine is cold, it richens up the mixture to assist in the warming of the engine.

 

[blacksnapon]

TSB
06-23-9 HESITATION, RUNS ROUGH, OR SURGE EITHER ON ACCELERATION OR DURING IDLE IN GEAR AND OCCURS RIGHT AFTER INITIAL COLD ENGINE START UP

Publication Date: November 6, 2006

FORD: 2005-2007 F-Super Duty


ISSUE:
Some 2005-2007 F-Super Duty vehicles equipped with a 6.8L 3V engine may exhibit a concern described by the customer as a hesitation, runs rough, or surge either on acceleration or during idle in gear, and occurs right after initial cold engine start up. This concern is intermittent and lasts 15 seconds or less.

ACTION:
Reprogram the powertrain control module (PCM) to the latest calibration using IDS release IDS 46.3 and higher. This new calibration is not included in the 2006.11 DVD. Calibration files may also be obtained at www.motorcraft.com.

 

[techrowe]

I will check temperature sensors i think i did before and just kept looking because they were normal but will double check.As far as the mentioned TSB the concern is intermittent and not only after cold start and will last for long periods when it does happen.Thanks for the input will keep checking also going to spray harnesses with salt water solution has seemed to be wet and sloppy out when drivers complained of concern.

 

[techrowe]

at this time i cannot get vehicle to act up again have checked all grounds and terminal tensions.Anyone have a ny knowledge on the importance FRP sensor and the amount that ford PCM's use it for fuel delivery?????when truck act up it reads 0psi and as said sensors have been swaped with known good one without change.unable to locate any harness concerns so far.when happens again and is repaired will be sure to post findings

 

[blacksnapon]

Fuel Rail Pressure (FRP) Sensor
The FRP sensor is a diaphragm strain gauge device in which resistance changes with pressure. The electrical resistance of a strain gauge increases as pressure increases, and the resistance decreases as the pressure decreases. The varying resistance affects the voltage drop across the sensor terminals and provides electrical signals to the PCM corresponding to pressure.

Strain gauge type sensors are considered passive sensors. A passive sensor is connected to a voltage divider network so that varying the resistance of the passive sensor causes a variation in total current flow.

Voltage that is dropped across a fixed resistor in series with the sensor resistor determines the voltage signal at the PCM. This voltage signal is equal to the reference voltage minus the voltage drop across the fixed resistor.

The FRP sensor measures the pressure of the fuel near the fuel injectors. This signal is used by the PCM to adjust the fuel injector pulse width and meter fuel to each engine combustion cylinder.



Fuel Rail Pressure Temperature (FRPT) Sensor
The FRPT sensor measures the pressure and temperature of the fuel in the fuel rail and sends these signals to the PCM. The sensor uses the intake manifold vacuum as a reference to determine the pressure difference between the fuel rail and the intake manifold. The fuel return line to the fuel tank has been deleted in this type of fuel system. The relationship between fuel pressure and fuel temperature is used to determine the possible presence of fuel vapor in the fuel rail. Both pressure and temperature signals are used to control the speed of the fuel pump. The speed of the fuel pump sustains fuel rail pressure which preserves fuel in its liquid state. The dynamic range of the fuel injectors increase because of the higher rail pressure, which allows the injector pulse width to decrease.




Fuel Rail Temperature (FRT) Sensor
The FRT sensor is a thermistor device in which resistance changes with temperature. The electrical resistance of a thermistor decreases as the temperature increases, and the resistance increases as the temperature decreases. The varying resistance affects the voltage drop across the sensor terminals and provides electrical signals to the PCM corresponding to temperature.

Thermistor-type sensors are considered passive sensors. A passive sensor is connected to a voltage divider network so that varying the resistance of the passive sensor causes a variation in total current flow.

Voltage that is dropped across a fixed resistor in series with the sensor resistor determines the voltage signal at the PCM. This voltage signal is equal to the reference voltage minus the voltage drop across the fixed resistor.

The FRT sensor measures the temperature of the fuel near the fuel injectors. This signal is used by the PCM to adjust the fuel injector pulse width and meter fuel to each engine combustion cylinder.