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Powerstroke Information
USEFUL POWERSTROKE INFORMATION
AP: Accelerator Pedal position sensor
Load/demand input; PCM uses this to determine mass fuel desired, adjusts fuel delivery
through IPR duty cycle and fuel pulse width and injection timing; 5 volts in, 0.5-0.7 volts at idle,
4.5 volts at WOT. PID: AP
BARO: Barometric pressure sensor
Strategy input; PCM uses this to adjust fuel quantity and injection timing for optimum running
and minimum smoke, also glow plug on time to aid starting at higher altitudes; 5 volts in, @4.6
volts/14.7 psi at sea level, decreasing as altitude increases. PID: BARO (pressure)
CMP: CaMshaft Position sensor
Strategy and load input; PCM uses this to monitor engine speed to determine engine state
and load, and cylinder position in order to control timing and fuel delivery; Hall Effect sensor
which generates a digital voltage signal; high, 12 volts, low, 1.5 volts. PID: RPM
DTC: Diagnostic Trouble Code
System malfuction or fault codes stored in the PCM to aid in diagnosis.
EBP: Exhaust BackPressure sensor
Feedback input; PCM uses this to monitor and control EPR operation; 5.0 volts in, 0.8-1.0
volts/14.7 psi KOEO or at idle, increases with engine RPM/load, decreases as altitude
increases. PID: EBP (pressure), EBP V (volts)
EOT: Engine Oil Temperature sensor
Strategy input; PCM uses this for determining glow plug on time, EPR actuation, idle speed,
fuel delivery and injection timing and adjusts as temperature increases; 5.0 volts in, 4.37
volts@32°F, 1.37volts@176°F, .96volts@205°F. PID: EOT (degrees)
EPR: Exhaust backPressure Regulator, also EBP regulator
Output; For quicker engine warm-up at cold temperatures. If the IAT is below 37°F (50°F
some models) and the EOT is below 140°F (168° some models) the PCM sends a duty cycle
signal to a solenoid which controls oil flow from the turbo pedestal. This causes a servo to
close a valve at the turbo exhaust outlet. The PCM monitors the EBP input to determine if the
EPR needs to be disabled to provide power for increased load, then reapplys the EPR as load
demand decreases until EOT or IAT rises. PID: EPR (duty cycle), EBP (pressure)
GPC: Glow Plug Control
Output; The PCM energizes the glow plug relay for 10 to 120 seconds depending on EOT and
BARO. PID: GPC (time)
GPL: Glow Plug Light
Output; The PCM controls the "Wait to start" light independently from the GPC output; 1 to 10
seconds depending on EOT and BARO. PID: GPL.
GPM: Glow Plug Monitor
Feedback input; On 1997 and newer California emission vehicles, the PCM monitors glow plug
relay output voltage to determine if any glow plugs are burned out or if the relay is functioning.
PID: GPML (left bank current), GPMR (right bank current), GPMC (relay output)
IAT: Intake Air Temperature sensor
Strategy input; The PCM uses this for EPR control. 5 volts in, 3.897volts@32°F, 3.09@68°F,
1.72@122°F. PID: IAT (degrees)
ICP: Injection Control Pressure sensor
Feedback input; The PCM monitors the high pressure oil system to determine if it needs to be
increased if load demand increases. It also uses this to stabilize idle speed. volts in,
1.0volt@580psi, 3.22volts@2520psi. PID: ICP (pressure), ICP V (voltage)
IDM: Injector Driver Module
The PCM sends a Cylinder Identification and Fuel Demand Control signal to the IDM. The IDM
sends a 110 volt signal to the injectors. It then grounds each injector as fuel is required for
that cylinder. Fuel Pulse width is increased to deliver more fuel. The IDM sends a feedback
signal to the PCM for fault detection. PID: FuelPW Fuel Pulse Width signal from PCM
(milliseconds)
IPR: Injection Pressure Regulator
Output; The PCM controls the high pressure oil system by varying the duty cycle of the IPR.
The IPR controls the oil bypass circuit of the high pressure pump. 0%=full return to sump
(open valve), 100%=full flow to injectors (closed valve). The PCM monitors the system with the
ICP input. The PCM can control fuel delivery to the injectors by increasing the IPR duty cycle
which increases fule pressure through the injector nozzels. PID: IPR (% of duty cycle), MFDES
Mass Fuel Desired an internal PCM calculation based on load demand (MG)
IVS:Idle Validation Switch
Strategy input; On-off switch that the PCM uses to identify required operating mode; idle or
power. 0 volts at idle, 12 volts off idle. PID: IVS (off/on)
MAP: Manifold Absolute Pressure sensor
Strategy and feedback input; The PCM monitors manifold pressure to control fuel delivery in
order to minimize smoke. It also optimizes injection timing for detected boost. It also monitor
boost to limit fuel delivery to control maximum turbo boost. Frequency output; 111Hz=14.7psi,
130Hz=20psi, 167Hz=30psi. PID: MAP (pressure basline 14.7psi), MAP HZ (frequency), MGP
Manifold Gauge Pressure (pressure base line 0psi) turbo boost
MAT:Manifold Air Temperature sensor
Strategy input; The PCM uses this signal to adjust fuel and timing. 99 model/year engines.
PID: MAT
MIL: Malfuction Indicator Lamp
"Check Engine" or "Service Engine" light that the PCM illuminates when certain system faults
are present.
PCM: Powertrain Control Module, also ECU or ECM for Electronic Control Unit or
Module
The computer which monitors sensor inputs and calculates the necessary output signals to
the engine control systems. It also checks for readings outside of normal parameters a
records trouble codes for these faults.
PID: Parameter IDentification, also Data Stream or Sensor Data
Sensor readings displayed to a scan tool that represent sensor readings to- and ouput
signals from the PCM.
Useful PID comparisons
AP--Accelerator Pedal--and IVS--Idle Validation Switch: IVS should switch state when AP
voltage is approximatly 0.2-0.3 volts higher than base idle position.
ICP--Injection Control Pressure--IPR--Injection Pressure Regulator--and MFDES--Mass Fuel
Desired: ICP should rise as IPR duty cyle increases; MFDES and IPR should rise at the same
rate as load and/or demand increases (actual readings may not match); ie. ICP=500psi,
IPR=12%, MFDES=10MG @500 RPM; ICP=900psi, IPR=22%, MFDES=20MG
@1800RPM/cruise; ICP=1800psi, IPR=50%, MFDES=40MG @3000RPM/hard accel.
ICP--Injection Control Pressure--and RPM--CaMshaft Position Sensor: After 3 minutes at 3300
RPM, ICP pressure should be below 1400psi for Federal, 1250psi for California Emmisions,
and 1500psi for 99.5. At idle, ICP should be 550-700psi for Federal, 400-600 for California
and stable.
V PWR--Battery Voltage--RPM--CaMshaft Position sensor--ICP--Injection Control
Pressure--FuelPW--Fuel Pulse Width: When starting V PWR should be above 10volts, ICP
should be at least 500psi, at least 100RPM, and FuelPW 1mS-6mS. Once the PCM
recognizes CMP speed and cylinder ID, FuelPW should default to 0.42mS, 0.60mS for 99 up,
until ICP reaches starting pressure.
EOT--Engine Oil--and IAT--Intake Air Temperatures: After a cold soak, before starting EOT
and IAT should be within 10 degrees of each other, Key On Engine Off.
BARO--Barometric--MAP--Manifold Absolute--and EBP--Exhaust BackPressures: All three
should indicate atmospheric pressure (14.7psi at sea level) and read within 0.5 psi of each
other, Key On Engine Off.
ICP--Injection Control Pressure--and ICP V--ICP Voltage: ICP should read 0psi, ICP V should
read 0.20-0.25 volts, Key On Engine Off.
EBP--Exhaust BackPressure--MGP--Manifold Gauge Pressure--and RPM--CaMshaft Position
Sensor: At full throttle in neutral, EBP should be below 28psi; At full throttle in fourth (manual)
or third (auto) gear, MGP should be 15psi.
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7.3L Injector "Buzz" Test
The Injector "Buzz" Test can be used to look for a faulty fuel injector. It is best to run this test
on a totally cold engine, one that has sat overnight and has not been started.
Initiate the "Buzz" test and then listen carefully to the injectors as the test is completed. First,
all 8 injectors will "Buzz" at the same time. Then, the IDM will "Buzz" the injectors in numerical
order (1, 2, 3, 4, 5, 6, 7, 8). Remember that cylinders 1-3-5-7 are on the passenger side and
2-4-6-8 are on the drivers side, with cylinders 1 & 2 being at the front of the engine. You
should hear a strong "Buzz" bouncing from side to side for all 8 injectors. If one of the
injectors doesn't "Buzz", you've found a problem cylinder. It is important to note that when an
injector fails to "Buzz" properly, you will still hear the other 7 injectors make a faint buzz...this
is a designed function to protect the IDM. Remember, The buzz test is not an audio test only,
you should get fault codes with this test.
Note: Because the IDM will "buzz" the other 7 injectors faintly during individual cylinder tests,
it is possible for the "Buzz" test to report no problems detected. If the "Buzz" test reports no
failures, but you don't hear a particular cylinder "Buzz"...more than likely there is a problem
with that injector.
It should also be noted that an injector failing a "Buzz" test can have many causes. The
injector can be in a failed state (loose armature plate screw, bad solenoid, etc.), the UCV
(under valve cover) gasket or harness could be damaged or disconnected, the main engine
harness could be damaged or the IDM could be damaged. Further inspection will be
necessary to determine the actual problem...but at least you now have a place to start.
Quick KOEO Sensor Checks:
There are a few sensors that can be easily checked with a scantool. Starting with a "Dead
Cold" engine (let it sit overnight, don't start), connect to the truck with the ScanTool. Check
the following:
Oil Temp should closely match the current Ambient Temp.
Readings for Exhaust Backpressure, Manifold Absolute Pressure and Barometric Pressure
should all be within 1/2 psi of each other (this should be true with the engine either warm or
cold).
(Note: with the engine running, MAP and EBP values are "Pressure + Baro". For example, if
Baro is 14.7 and there is 2psi of boost, MAP will read 16.7. Also, there is a calculated PID
called "Manifold Gauge Pressure" that doesn't have the Baro pressure added in).
KOER (Key On Engine Running) On-Demand Test:
On the 7.3L, the primary purpose of this test is to check the functionalilty of the High
Pressure Oil System and the Exhaust Back Pressure Solenoid. On the 6.0L this test may
return Misfire, VGT or Glowplug codes.
Requirements to Start (7.3L and 6.0L)
7.3L Powerstroke Starting Req.: 6.0L Powerstroke Starting Req.:
Vehicle Power : 10.5v Vehicle Power : 10.5v
RPM Signal : 100rpm RPM Signal : 100rpm
Inj. Cntrl Press. (ICP) : 0.85v (about 500psi) Inj. Cntrl Press. (ICP) : 0.85v (about 500psi)
Fuel Pulse Width : 1 to 6 milliseconds Fuel Pulse Width : 0.5 to 2 milliseconds
FICM SYNC and SYNC Achieved
Note: the above starting requirements for both 7.3L and 6.0L Powerstroke Diesels assume
the following:
Sufficient Base Engine Oil Level and Pressure
Acceptable Quality Fuel
Sufficient Fuel Pressure
Sufficient Air Supply
Proper Glow Plug Operation
Proper Injection Timing (PCM Controlled)
