Checks
| Action
|
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.
|
Preliminary
|
| • | Refer to Important Preliminary Checks. |
| • | Refer to Visual/Physical Checks |
|
Sensor/System
|
| • | Test the heated oxygen sensors (HO2S). The HO2S should respond
quickly to different throttle positions. If the sensors do not respond properly,
inspect the HO2S 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, HO2S signal voltage. The PCM reduces
the amount of fuel delivered to the engine, causing a severe driveability
problem. Refer to
Information Sensors/Switches Description
. |
| • | Test the throttle position (TP) sensor and the related wiring. |
| • | Test the mass air flow (MAF) sensor and the related wiring. |
|
Fuel
System
|
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Ignition
System
|
| • | Test for proper ignition voltage output using the following procedure: |
| - | Clip the J 26792
spark tester to engine ground. |
| - | Connect one end of a spark plug wire to the spark tester. Leave
the other end of the spark plug wire connected to the coil being tested. |
| - | Connect one end of another spark plug wire to the other coil tower.
Connect the other end of the spark plug wire to ground. |
| - | Crank the engine while observing the spark tester. Spark should
be observed. |
| - | Repeat the above steps for each coil. |
| • | If adequate spark is not present at the coils, inspect or test
for the following conditions: |
| - | Inspect the coils for cracks, carbon tracking/arcing, or a resistance
value outside the 5000 - 8000 ohms range. |
| - | Inspect the spark plug wires for signs of arcing/cross firing,
cracks, carbon tracking, plug boot damage, pinched wires, improper routing,
or a resistance value other than 600 ohms per ft. (1968 ohms
per meter). |
| | Important: Spraying the secondary ignition wires with a light mist of water may
help locate an intermittent problem. Ignition components arc to ground when
a secondary component is faulty.
|
| - | Test for a defective module. |
| - | Inspect the ignition system wiring for a loose ignition module
feed or ground connection, or damaged system wiring. |
| • | Remove the spark plugs and inspect for the following: |
| - | Burned or damaged electrodes |
| - | Improper heat range or reach |
| • | If the spark plugs are gas or oil fouled, the cause of the fouling
must be determined before replacing the spark plugs. |
|
