Checks
| Action
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DEFINITION: The engine cranks OK, but takes a long time to start. The
engine does eventually run, or may start, but immediately dies. Note: It is
normal to have a longer crank time on CNG.
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Preliminary Checks
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| • | Verify that the vehicle's operator is using the correct starting
procedure. |
| • | Search for service bulletins. |
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Sensor/System Checks
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| • | Inspect the engine coolant temperature (ECT) sensor with the scan
tool. Compare the engine coolant temperature with the ambient air temperature
on a cold engine. If the coolant temperature readings is more than five
degrees greater or less than the ambient air temperature on a cold engine,
inspect for high resistance in the ECT sensor circuit. Refer to Temperature
vs. Resistance in Engine Controls - 2.2L in the J Platform Service Manual.
If the ECT sensor resistance is not within the specification. refer to
DTC P0118 ECT Sensor Circuit High Voltage or DTC P0117 ECT Sensor Circuit
Low Voltage in Engine Controls - 2.2L in the J Platform Service Manual. |
| • | Inspect the throttle position (TP) sensor. If a sticking throttle
shaft or binding linkage causes a high TP sensor voltage (open throttle indication),
the control module will not control the idle. While monitoring the TP
sensor voltage, the scan tool should display less than 0.90 volt
with the throttle closed. |
| • | Inspect the crankshaft position sensor (CKP). |
| • | Verify proper operation of the IAC valve. |
| • | Inspect the EGR system for the following conditions: |
| - | Leaks in the EGR pipes and the adapter. |
| - | Inspect for a stuck open pintle by removing the EGR valve. |
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Fuel System Checks
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Important: A closed manual shut-off valve will create an extended crank condition.
| • | Inspect the fuel pump relay for proper operation. The fuel pump
relay circuit supplies a voltage signal to the AF system ECU and the lock-off
relay. Refer to Fuel Pump Relay Circuit Diagnosis in Engine Controls -
2.2L in the J Platform Service Manual. |
| • | Inspect the gas distribution adapter (GDA) for proper installation
and leakage. |
| • | Inspect for an open NGO enable circuit. |
|
Ignition System Checks
| CNG is a gaseous fuel. It requires higher secondary ignition system
voltages for the equivalent gasoline operating conditions. If a problem is
reported during CNG operating but not during gasoline operation, do not
discount the possibility of a CNG-only ignition system failure. Test the
system accordingly.
| • | Verify proper ignition voltage output using the J 26792
or the equivalent. |
| • | Inspect the spark plugs for the following conditions: |
| - | Cracks on the spark plugs |
| - | Improper spark plug gap |
| • | Inspect the spark plug wires for proper resistance and condition. |
| • | Inspect the ignition coils for cracks or carbon tracking. |
| • | Inspect for loose ignition coil connections. |
| • | Inspect for lose engine control module grounds. |
| • | Inspect for loose ignition control module grounds. |
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Engine Mechanical Checks
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Important: The AF system delivers fuel to the intake system through fumigation.
This method is more sensitive to intake manifold leakage than the gasoline
fuel supply system.
| • | Check for the following conditions: |
| - | Broken or weak valve springs |
| • | Inspect the intake and exhaust manifolds for casting flash. Refer
to Intake Manifold Clean and Inspect and Exhaust Manifold Clean and Inspect
in Engine Mechanical - 2.2L in the J Platform Service Manual. |
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Additional Checks
| If all the procedures have been completed and no malfunction has been
found, review and inspect the following items:
| • | Visually and physically inspect all electrical connections within
the suspected circuit and systems. |
| • | Verify the correct PCM software is installed. |
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