Dtc P1093 (Flash Code 227) - Isuzu N 2008 Series Workshop Manual

DTC P1093 (Flash Code 227)

Description
The common rail fuel system is comprised of two fuel
pressure sections: a suction side between the fuel tank
and the fuel supply pump and a high-pressure side
between the fuel supply pump and the fuel injectors.
Fuel is drawn from the fuel tank via a feed pump and
then pumped into the fuel rail by two plungers, all of
which are internal to the fuel supply pump. This high
pressure is regulated by the ECM using the fuel rail
pressure (FRP) regulator dependant upon values from
the FRP sensor attached to the fuel rail. If the ECM
detects that the fuel rail pressure is certain pressure
lower than the desired pressure, this DTC will set.
Condition for Running the DTC
• DTC P0087, P0091, P0092, P0192, P0193, P0201
- P0204, P060B, P0651, P1261, P1262, P2146
and P2149 are not set.
• The battery voltage is between 18 to 32 volts.
• The ignition switch is ON.
• The engine is running.
• The FRP regulator commanded fuel flow is more
than a threshold.
Condition for Setting the DTC
• The ECM detects that the actual fuel rail pressure
is more than 50 MPa (7,200 psi) below the desired
pressure for longer than 5 seconds.
Action Taken When the DTC Sets
• The ECM illuminates the MIL when the diagnostic
runs and fails. Refer to DTC Type Definitions for
Action Taken When the DTC Sets - Type A.
• The ECM limits fuel injection quantity.
• The ECM inhibits pre injection.
• The ECM inhibits EGR control.
Circuit/ System Testing DTC P1093
Step
Did you perform the Diagnostic System Check -
1 Engine Controls?
1. Install a scan tool.
2. Turn OFF the ignition for 30 seconds.
3. Start the engine.
2
4. Monitor the DTC Information with a scan tool.
Is DTC P0087, P0091, P0092, P0192, P0193,
P0201 - P0204, P2146 or P2149 set?
Action
Engine Control System (4JJ1)
Condition for Clearing the DTC
• Refer to DTC Type Definitions for Condition for
Clearing the MIL/ DTC - Type A.
Diagnostic Aids
• An intermittently sticking FRP regulator may have
allowed the fuel pressure to become low enough to
set this DTC.
• Normal Fuel Rail Pressure readings on the scan
tool with the engine running in neutral at idle is
around 27 to 33 MPa (3,900 to 4,800 psi) after
warm up.
• A skewed FRP sensor value can set this DTC. The
FRP Sensor on the scan tool should read 0.9 to
1.0 volt with the ignition switch ON and engine
OFF after the engine has stopped running for a
minimum of 1 minute.
Notice: This DTC most likely indicates a loss of fuel
pressure by a fuel leak from the high pressure side.
Inspect the high pressure side fuel leakage between
the fuel supply pump and fuel injector first.
Notice: If the fuel tank is empty or near empty, air
might be allowed to go into the fuel system. With air in
the fuel system, smooth flow of fuel into the supply
pump is interrupted and this DTC may set. Perform
bleeding of fuel system after refilling.
Test Description
The numbers below refers to the step number on the
Circuit/ System Testing.
5. This step checks for a fuel restriction by determining
if a high vacuum is being pulled on the fuel system
during normal operation.
6. This step checks for an air leak on the suction side of
the fuel system by determining if a vacuum can be
pulled when a fuel line is plugged.
Routing Reference: Fuel System Routing Diagram
Connector End View Reference: Engine Controls
Connector End Views or ECM Connector End Views
Value(s) Yes
—
Go to Step 2
—
Go to Applicable
DTC
1A-217
No
Go to Diagnostic
System Check -
Engine Controls
Go to Step 3