Cuts Out, Misses
Checks
| Action
|
DEFINITION: A steady pulsation
or jerking that increases with the engine speed. The condition is usually
more pronounced when the engine load increases.
|
Preliminary
|
| • | Search the service bulletins. |
|
Fuel System
| Check for the following
conditions:
| • | Check for a restricted fuel filter. |
| • | Conditions which can cause an engine to run rich, indicating that
the long-term fuel trim is significantly in the negative range--Refer
to Diagnostic Aids for
DTC P0172
. |
| • | Conditions which can cause an engine to run lean, indicating that
the long-term fuel trim is significantly in the positive range--Refer
to Diagnostic Aids for
DTC P0171
. |
| • | Proper operation of the evaporative emission (EVAP) control
system |
| • | Check for fuel in the fuel pressure regulator vacuum hose. |
|
Sensor/System
| Check for the following conditions:
| • | The oxygen sensor (O2S 1)--The O2S 1 should
quickly respond to the different throttle positions. If it does not respond,
check the O2S 1 for silicon, or for other contaminants from
the fuel, or from the use of an improper RTV sealant. The sensor
may have a white powdery coating. Silicon contamination causes
a high but false O2S 1 signal voltage, indicating a rich
exhaust indication. The PCM will reduce the amount of fuel
that is delivered to the engine, causing a severe driveability
problem. |
| • | Proper operation of the following components: |
| - | The manifold absolute pressure (MAP) sensor |
| - | The throttle position (TP) sensor |
| - | The engine coolant temperature (ECT) sensor |
|
Ignition System
| Check for the following conditions:
| • | Proper ignition voltage output--Use the J 36012-A
Spark Plug Jumper Wires and the J 26792
Spark Tester, or equivalent. |
| • | Check the spark plugs for the following conditions: |
| - | Fuel-fouled spark plugs |
| - | Improper spark plug gap |
| • | If the spark plugs are fuel or oil-fouled, determine the cause
of the fouling before you replace the spark plugs. |
| • | The ignition control module (ICM) for proper ground connection |
| • | The ignition coils for cracks or carbon tracking |
| • | The internal and external ignition coil housing for cracks and
for carbon tracking |
|
Engine Mechanical
| Check for the following conditions:
| • | Excessive oil in the combustion chamber, caused by leaking valve
seals |
| • | Low cylinder compression |
| • | Incorrect basic engine parts--Inspect the following components: |
| - | Other components, as necessary |
|
Additional Checks
|
| • | Check the exhaust system for possible restrictions. Check for
the following conditions: |
| - | Inspect the exhaust system for damaged pipes, or for collapsed
pipes. |
| - | Inspect the mufflers for heat distress, or for possible internal
failure. |
| - | Inspect for a plugged 3-way catalytic converter. Refer to
Restricted Exhaust
in Engine Exhaust. |
| • | Electromagnetic interference (EMI) on the reference circuit can
cause an engine miss condition. You can usually detect EMI by monitoring
the engine RPM with a scan tool. A sudden increase in the RPM, with little
change in the actual engine RPM change indicates that EMI
is present. If a problem exists, check the routing for the
following components: |
| - | The secondary ignition wires |
| - | The high-voltage components, near the ignition control circuits |
| • | The following conditions can cause an intermittent connection: |
| - | Poor electrical connections |
| - | Rubbed through wire insulation |
| - | Broken wire inside the insulation |
| • | Thoroughly check any circuitry that you suspect of causing an
intermittent complaint for the following conditions: |
| - | Improper terminal mating |
| - | Improperly-formed terminals |
| - | Poor terminal-to-wire electrical connections |
| - | A damaged wiring harness |
|
