Checks
| Action
|
DEFINITION: Momentary
lack of response when the accelerator is pushed down. This lack of response
can occur at any vehicle speed. This condition is usually more pronounced
when the driver is initially attempting to accelerate the vehicle, such
as from a full stop. If the condition is severe, the engine can stall during
the acceleration.
|
Preliminary
|
|
Sensor/System
|
| • | Test the heated oxygen sensors (HO2S). The HO2S should respond
quickly to different throttle positions. If not, inspect the HO2S for
the following contaminants: |
| - | A white powdery coating--Silicon contamination causes
a high, but false, HO2S signal voltage, which is a rich-exhaust indication.
The PCM will reduce the amount of fuel delivered to the engine, causing
a severe driveability condition. |
| - | Use of incorrect RTV sealant |
| • | Test the throttle position (TP) sensors and inspect the related
wiring. |
| • | Test the mass air flow (MAF) sensor and inspect the related wiring. |
|
Fuel System
|
| • | Test items which can cause an engine to run rich, with the long-term
fuel trim (FT) significantly in the negative range. Refer to Diagnostic Aids
for
DTC P0172 or P0175
. |
| • | Test items that can cause an engine to run lean, with the long-term
FT significantly in the positive range. Refer to Diagnostic Aids for
DTC P0171 or P0174
. |
|
Ignition System
|
| • | Test for proper ignition voltage output using the following steps: |
| 1. | Clip the J 26792
Spark
Tester to engine ground. |
| 2. | Connect one end of a spark plug wire to the spark tester. Connect
the other end of the spark plug wire to the coil being tested. |
| 3. | Connect another spark plug wire between the remaining tower of
the coil being tested and ground. |
| 4. | Crank the engine while observing the spark tester, a spark should
be observed. |
| 5. | Repeat the above steps for each coil. |
| • | Coils--Evidence of carbon tracking or arcing, cracks in the
coils, or a resistance value outside the specified range: |
Coil Secondary Resistance
5000-8000 ohms (5K-8K ohms)
| | Important: Spraying the secondary ignition wires with a light mist of water may
help locate an intermittent condition. Ignition components will arc to ground
when a secondary component is malfunctioning.
|
| • | Spark plug wires--Inspect for the following conditions: |
| - | Evidence of cross firing |
| • | Spark plug wires--Inspect for a resistance value more than
the specified value: |
Spark Plug Wires Resistance
3280-4921 ohms/meter (1000-1500 ohms/ft) | • | Malfunctioning ignition control module |
| • | If spark is not present at the coils, test for the following conditions: |
| • | Remove spark plugs and inspect for the following conditions: |
| - | Burned or damaged electrodes |
| • | If spark plugs are gas or oil fouled, the cause of the fouling
must be determined before replacing the spark plugs. |
|
