Surges/Chuggles
Checks
| Action
|
DEFINITION: Engine power variation under steady throttle or cruise.
Feels like the vehicle speeds up and slows down with no change
in the accelerator pedal.
|
Preliminary
|
| • | Search for service bulletins. |
| • | Ensure that the driver understands the transmission torque converter
clutch (TCC) and the air conditioning (A/C) compressor operation as explained
in the owners manual. Inform the customer how the TCC and the A/C clutch
operates. |
| • | Ensure that the powertrain control module (PCM) grounds are clean,
tight, and in the proper location. |
|
Sensor/System
|
| • | Inspect the oxygen sensor (O2S) 1 and the heated oxygen
sensor (HO2S) 2. The O2S 1 and HO2S 2 should respond
quickly to different throttle positions. If not, inspect the
O2S 1 and the HO2S 2 for silicon or other contaminants
from fuel or the use of improper RTV sealant. The sensors may have
a white powdery coating. Silicon contamination causes a high
but false O2S 1 and HO2S 2 signal voltage, indicating
a rich exhaust indication. |
| | The powertrain control module (PCM) will reduce the amount
of fuel delivered to the engine, causing a severe driveability problem.
Refer to
Diagnostic Trouble Code (DTC) List
for O2S and HO2S diagnostics. |
| • | Ensure proper operation of the manifold absolute pressure (MAP)
sensor. |
| • | Ensure proper operation of the throttle position (TP) sensor. |
| • | Ensure proper operation of the engine coolant temperature (ECT)
sensor. |
|
Fuel
System
|
| • | Inspect the fuel filter for plugs or restrictions. |
| • | Inspect the items which can cause an engine to run rich, for example,
the long term fuel trim is significantly in the negative range. Refer to Diagnostic
Aids for
DTC P0172
. |
| • | Inspect the items that can cause an engine to run lean, for example,
the long term fuel trim is significantly in the positive range. Refer to Diagnostic
Aids for
DTC P0171
. |
|
Ignition
System
|
| • | Ensure proper ignition voltage output with J 26792
Spark Tester or equivalent. |
| • | Inspect the spark plugs for the following conditions: |
| - | Wet or fuel fouled spark plugs |
| - | Cracks on the spark plugs |
| - | Improper spark plug gap |
| - | Burned electrodes or heavy deposits |
| • | If the spark plugs are fuel or oil fouled, determine the cause
of the fouling before replacing the spark plugs. |
| • | Inspect the ignition control module (ICM) for proper ground connection. |
| • | Inspect the ignition coils for cracks or carbon tracking. |
| • | Inspect the spark plug wires for proper resistance and condition. |
|
Additional
Checks
|
| • | Inspect the exhaust system for a possible restriction: |
| - | Inspect the exhaust system for damaged or for possible collapsed
pipes. |
| - | Inspect the muffler for heat distress or for possible internal
failure. |
| - | Inspect for a possible plugged three-way catalytic converter (TWC).
Refer to
Restricted Exhaust
in Engine
Exhaust. |
| • | Inspect the vacuum lines for kinks or for leaks. |
| • | Inspect the generator output voltage. Repair the generator if
the output voltage is less than 11 volts or more than 16 volts. |
| • | If all procedures have been completed and no malfunctions have
been found, review and inspect the following items: |
| - | All electrical connections within the suspected circuit and/or
systems |
|
