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1G-26 Fuel System:
Diagnostic Aids
• Monitoring the misfire current counters, or misfire
graph, may help to isolate the fuel injector that is
causing the condition.
• Operating the vehicle over a wide temperature range
may help isolate the fuel injector that is causing the
condition.
• Perform the fuel injector coil test within the conditions
of the customers concern. A fuel injector condition
may only be apparent at a certain temperature, or
under certain conditions.
• If the condition is intermittent, move the related
harnesses and connectors, with the engine operating,
while monitoring the circuit status for the component
with a scan tool. The circuit status parameter changes
from OK or Indeterminate to Fault if there is a
condition with the circuit or a connection.
Reference Information
Schematic Reference
"Engine Controls Schematics: "
Electrical Information Reference
• "Circuit Testing: "
• "Connector Repairs: "
• "Testing for Intermittent Conditions and Poor
Connections: "
• "Wiring Repairs: "
Fuel Injector Balance Test with Special Tool
Diagnostic Instructions
• Perform the "Diagnostic System Check - Vehicle Diagnostic Information: " prior to using this diagnostic procedure.
• Review "Strategy Based Diagnosis: " for an overview of the diagnostic approach.
• "Diagnostic Procedure Instructions - Vehicle Diagnostic Information: " provides an overview of each diagnostic
category.
Diagnostic Fault Information
Fuel Injector Balance Test Example
Cylinder
360 kPa (52
First Reading
psi)
Second
195 kPa (28
Reading
psi)
Amount Of
166 kPa (24
Drop
psi)
Average
Range: 156-
Injector OK
176 kPa (22.5-
25.5 psi)
1
2
360 kPa (52
psi)
138 kPa (20
psi)
222 kPa (32
psi)
Fuel Injector -
Too Much
Pressure Drop
Component Testing
Verify the resistance of each fuel injector with one of the
following methods:
• If the engine coolant temperature (ECT) sensor is
between 10-32°C (50-90°F), the resistance of each
fuel injector should be 11-14 ohms.
➢ If the resistance of any fuel injector is not 11-14
ohms, replace the fuel injector.
• If the ECT sensor is not between 10-32°C (50-90°F),
measure and record the resistance of each fuel
injector with a DMM. Subtract the lowest resistance
value from the highest resistance value. The
difference between the lowest value and the highest
value should be equal to or less than 3 ohms.
➢ If the difference is equal to or less than 3 ohms,
refer to "Fuel Injector Balance Test with Special
Tool" or "Fuel Injector Balance Test with Tech 2" for
further diagnosis of the fuel injectors.
➢ If the difference is more than 3 ohms, add all of the
fuel injector resistance values to obtain a total
resistance value. Divide the total resistance value
by the number of fuel injectors to obtain an average
resistance value. Subtract the lowest, and the
highest, individual fuel injector resistance values
from the average resistance value. Replace the fuel
injector that displays the greatest resistance
difference above or below the average.
Repair Instructions
Perform the "Diagnostic Repair Verification - Vehicle
Diagnostic Information: " after completing the diagnostic
procedure.
"Fuel Injector Balance Test with Special Tool"
3
4
360 kPa (52
360 kPa (52
psi)
psi)
195 kPa (28
195 kPa (28
psi)
psi)
166 kPa (24
166 kPa (24
psi)
psi)
Injector OK
Injector OK
5
6
360 kPa (52
360 kPa (52
psi)
psi)
235 kPa (34
195 kPa (28
psi)
psi)
125 kPa (18
166 kPa (24
psi)
psi)
Faulty Injector -
Too Little
Injector OK
Pressure Drop
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Troubleshooting
