Hesitation, Sag, Stumble
Checks
| Action
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Definition: Momentary lack of response as the accelerator is pushed
down. Can occur at any vehicle speed. Usually more pronounced when first
trying to make the vehicle move, as from a stop sign. May cause the engine
to stall if severe enough.
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Preliminary
|
| • | Search for service bulletins. |
|
Sensor/System
|
| • | Check the oxygen sensor (O2S 1). The O2S 1 and HO2S 2
should respond quickly to different throttle positions. If not, check the
O2S 1 for silicon or other contaminants from fuel or the use of improper
RTV sealant. The sensor may have a white powdery coating. Silicon contamination
causes a high but false O2S 1 signal voltage (rich exhaust indication).
The PCM will reduce the amount of fuel delivered to the engine, causing
a severe driveability problem. Refer to oxygen sensor in
Information Sensors/Switches Description
. |
| • | Check the EGR valve for a stuck open pintle. |
| • | Check for proper operation of the MAP Sensor. |
| • | Check for proper operation of the TP sensor. |
| • | Check for proper operation of the ECT sensor. |
|
Fuel System
|
| • | Check for contaminated fuel. Refer to Alcohol/Contaminants-in-Fuel Diagnosis
. |
| • | Check items which can cause an engine to run rich (long term fuel
trim is significantly in the negative range). Refer to
DTC P0172 Fuel Trim System Rich
. |
| • | Check items that can cause an engine to run lean (long term fuel
trim is significantly in the positive range). Refer to
DTC P0171 Fuel Trim System Lean
. |
| • | Check for proper operation of the evaporative emission (EVAP)
control system. |
|
Ignition System
|
| • | Check for proper ignition voltage output with the spark plug jumper
wires J 36012-A
and spark tester J 26792
. |
| • | 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, the cause of the fouling
must be determined before replacing the spark plugs. |
| • | Check the ignition control module (ICM) for proper ground connection. |
| • | Check the ignition coils for cracks or carbon tracking. |
|
Additional Checks
|
| • | Check for proper operation of the Automatic Transaxle. |
| • | Check 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
not been found, review and inspect the following items: |
| - | Visually and physically inspect all electrical connections within
the suspected circuit and/or systems. |
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