Checks
| Action
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DEFINITION: The vehicle has a momentary lack of response when depressing
the accelerator. The condition can occur at any vehicle speed. The condition
is usually most severe when trying to make the vehicle move, such as
from a stop. The condition may cause the engine to stall if it's severe
enough.
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Preliminary Checks
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| • | Search for service bulletins. |
| • | Inspect the control module grounds. The grounds should be clean,
tight and in the proper locations. |
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Sensor Checks
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| • | Inspect the oxygen sensor (O2S) for contamination and performance. |
| • | Inspect for proper operation of the TP sensor. |
| • | Inspect for proper operation of the MAP sensor. |
| • | Inspect for proper operation of the ECT sensor. |
| • | Inspect the EGR valve for a stuck open pintle. |
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Fuel System Checks
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| • | Inspect for low fuel pressure during a moderate or full throttle
acceleration. If the fuel pressure drops below specification, there is possibly
a faulty low or high pressure regulator or a restriction in the fuel
system. |
| • | Inspect the evaporative emissions (EVAP) control system for proper
operation. Refer to EVAP Control System Diagnosis in Engine Controls - 2.2L
in the J Platform Service Manual. |
| • | Inspect the gas distribution adapter (GDA) for proper installation
and leakage. |
| • | Verify that the correct bi-fuel PCM software is installed. |
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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 operation but not during gasoline operation, do not
discount the possibility of a CNG-only ignition system failure. Test
the system accordingly.
| • | Inspect for the proper ignition output voltage using the J 26792
or the equivalent. |
| • | Inspect the spark plugs. Remove the plugs and inspect them 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 loose engine control module grounds. |
| • | Inspect for loose ignition control module grounds. |
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Additional Checks
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| • | Verify proper operation of the transaxle. Refer to Functional
Test Procedure in Automatic Transaxle - 3T40 or Automatic Transaxle - 4T40-E
in the J Platform Service Manual. |
| • | Inspect for manifold vacuum or air induction system leaks. |
| • | Verify the generator output voltage. Refer to Generator Usage
in Engine Electrical in the J Platform Service Manual. |
| • | Inspect the EGR valve for a stuck open pintle. |
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. |
| • | Inspect scan tool data. |
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