Diesel Engine Troubleshooting

Ford 7.3L DI Power Stroke

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Four engines, three of them built by International, go by the name “Power Stroke.” The first was the direct injection turbocharged 7.3L V-8. This engine, also known as the International T444E, powered F series trucks and E series vans between 1994 and 2003. The 32-valve 6.0L Power Stroke, or International VT 365, has been used on pickups and vans since 2004. Production of the 6.0 will end in 2007, when it will be replaced by a 6.4L V-8. The Ford V-6, aka DT17, has been used on low cab forward (LCF) trucks since 2005.

In many ways, the original 7.3L Power Stroke is the most interesting of the group. It carried Ford to first place in light diesel truck sales and generated a cult following not seen since the days of the Mustang. People have taken out second mortgages on their homes to buy these trucks.

The material dealing with the operation of HEUI injectors, the high-pressure oil pump, and the IAPCV also applies to the Power Stroke, although Caterpillar and Ford parts rarely interchange and pressure specifications vary. Table 6-4 translates Ford acronyms and describes sensor function. “Supply” is the voltage going to the sensor; “signal” is the sensor output to the computer (ECM).

AP Accelerator position sensor
Along with other variables, the ECM uses the AP signal to determine injector oil-pressure, pulse width and timing. Supply 5.0V +/_ 0.5V, signal 0.5–0.7V at idle, 4.5V at wide open throttle.
BARO Barometric pressure sensor
The ECM uses the BARO signal to adjust fuel timing, fuel quantity, and glow-plug on-time during high altitude operation. Supply 5.0V +/_ 0.5V, signal 4.6V at sea level, decreasing at higher altitudes.
CMP Camshaft position sensor
The ECM uses the CMP signal to monitor engine rpm and tdc for Nos. 1 and 4 cylinders. This Hall-effect sensor generates a digital voltage signal of 12.0V high, 1.5V low.
DTC Diagnostic trouble code
EBP Exhaust back pressure sensor
The ECM uses the EBP signal to control the exhaust pressure regulator (EPR). Supply 5.0V +/_ 0.5V, signal 0.8–1.0V @ 14.7 psi at idle, increasing with engine speed and load, decreasing with altitude.
EOT Engine oil temperature sensor
The ECM uses the EOT signal to control glow-plug on time, EPR, idle rpm and fuel delivery and timing. Supply 5.0V +/_ 0.5V, signal 4.37V @ 32°F, 1.37V @ 176°F, 0.96V @ 205°F.
EPR Exhaust back pressure regulator
The EPR operates hydraulically from oil taken off the turbocharger pedestal mount. When intake air temperature is less than 37°F (50°F on some models) and the engine oil temperature is less than 140°F (168°F on some models) the ECM energizes a solenoid valve that causes oil pressure to close a butterfly at the turbo exhaust outlet. The valve opens under load and as the engine warms.
GPC Glow plug control
The ECM energizes the GPC relay for 10–120 seconds depending on engine oil temperature and barometric pressure.
GPL Glow plug light
The ECM turns the “wait to start” lamp “on” for 1–10 seconds, depending on engine oil temperature and barometric pressure.
GPM Glow plug monitor
Used on 1997 and later California vehicles to report if glow plugs malfunction.
IAT Intake air temperature sensor
The ECM uses the IAT signal to regulate exhaust backpressure. Supply 5 V+/_0.5V, signal 3.90V @ 32°F, 3.09V @ 68°F, 1.72V @ 122°F.
IPC Injection pressure control sensor
The ECM uses the IPC signal to match fuel delivery with load and to stabilize idle rpm. Signal 1.00V @ 580 psi, 3.22V @ 2520 psi.
IDM Injector driver module
The IDM receives cylinder-identification and fuel-demand signals from the ECM, and generates a 115 VDC, 10A signal for the appropriate injector, varying pulse width as required.
IPR Injection pressure regulator
The ECM varies the duty cycle of the IPR to control oil pressure and the volume of fuel delivered. 0% = full return to sump (open valve), 100% = full flow to injectors (closed valve). Functioning is monitored by the Injector pressure control sensor.
IVS Idle validation switch
The IVS is an on-off switch that signals the ECM when the engine is idling. Signal 0V at idle, 12V off-idle.
MAP Manifold absolute pressure sensor
The MAP measures manifold pressure to limit turbo boost, optimize timing, and reduce over-fueling and smoke. Signal frequency: 111 Hz @ 14.7 psi, 130 Hz @ 20 psi, 167 Hz @ 30 psi.
MIL Malfunction indicator lamp
“Check engine” or “service engine” lamp that the ECM illuminates when certain system faults are present. Can also be used to retrieve trouble codes.
PCM Powertrain control module
PCM is the onboard computer that receives sensor inputs, calculates output signals to actuators, and generates diagnostic codes. The computer also controls transmission shift points, anti-skid braking, and other powertrain functions. Referred to in this text as the ECM.
PID Parameter identification
PID, or the data stream, is the sensor data read by scan tools.

Written by Ed

February 14th, 2011 at 7:46 am

Posted in Electronic Systems

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