Hesitation, Sag, Stumble
Checks
| Action
|
DEFINITION: A momentary lack
of response when the accelerator is pushed down. The condition can occur
at any vehicle speed. The condition is usually more pronounced
when the driver first attempts to make the vehicle move, such as
acceleration from a stop sign. The condition may cause the engine to stall
if severe enough.
|
Preliminary
|
| • | Search for service bulletins. |
|
Sensor/System
| Check for the following
conditions:
| • | Proper operation of the manifold absolute pressure (MAP) sensor |
| • | Proper operation of the throttle position (TP) sensor |
| • | Proper operation of the engine coolant temperature (ECT) sensor |
| • | Check the oxygen sensor (O2S 1). The O2S 1 should
quickly respond to the different throttle positions. If it does not, 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 delivered to the engine,
causing a severe driveability problem. |
|
Fuel System
| Check for the following
conditions:
| • | 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 that 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 |
|
Ignition System
| Check for the following conditions:
| • | Proper ignition voltage output--Use the J 36012-A
spark plug jumper wires and use
the J 26792
spark tester,
or equivalent. |
| • | Check 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 you replace the spark plugs. |
| • | The ignition control module (ICM) for proper ground connection |
| • | The ignition coils for cracks or for carbon tracking |
|
Additional Checks
| Check for the following conditions:
| • | Proper operation of the automatic transaxle |
| - | Refer to
Road Test
in
Automatic Transmission for 4T40. |
| - | Refer to
Road Test
in
Automatic Transmission for 3T40. |
| • | The generator output voltage--Repair the generator if the
output voltage is less than 11 volts, or more than 16 volts. |
| • | If you have completed all of the procedures, and if you have found
no malfunctions, review the following items: |
| - | Inspect all electrical connections within the suspected circuit
and/or systems. |
|
