Inspection/Tests
| 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. May cause the engine to stall if severe enough.
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Preliminary
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Sensor/System
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Notice: Refer to Silicon Contamination of Heated Oxygen Sensors Notice in the Preface section.
• | Inspect the heated oxygen sensors (HO2S). The HO2S should respond quickly to different throttle positions. If they do not, inspect the HO2S for silicon or other contaminates from fuel or the use of improper RTV sealant. The sensors may have a white,
powdery coating and result in a high but false signal voltage rich exhaust indication. The PCM will then reduce the amount of fuel delivered to the engine causing a severe driveability problem. |
• | Inspect the air intake ducts for being collapsed, damaged, loose, improperly installed, or leaking especially between the mass air flow (MAF) sensor and the throttle body. |
• | Verify that the engine coolant temperature (ECT) sensor is not shifted in value. Refer to
Temperature Versus Resistance
for resistance specifications. |
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Fuel System
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• | Inspect for the following conditions that may cause the engine to run rich: |
Notice: Refer to Heated Oxygen and Oxygen Sensor Notice in the Preface section. - | Water intrusion in the HO2S connector |
- | Engine oil contaminated by fuel |
- | An evaporative emission (EVAP) canister purge condition |
- | Vacuum hoses that are split, kinked, or improperly connected |
- | An air intake duct that is collapsed or restricted |
• | Inspect for the following conditions that may cause the engine to run lean: |
Notice: Refer to Heated Oxygen and Oxygen Sensor Notice in the Preface section. - | Water intrusion in the HO2S connector |
- | An exhaust leak between the HO2S and the engine--Refer to
Exhaust Leakage
in Engine Exhaust. |
- | Vacuum hoses that are split, kinked, or improperly connected |
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Ignition System
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• | Soak the secondary ignition system with water from a spray bottle. Soaking the secondary ignition system may help locate damaged or deteriorated components. Look and listen for arcing or misfiring as you apply water. Monitor the Misfire Current Counters
while driving the vehicle in the conditions that the misfire occurred. |
• | Remove the spark plugs and check for the following conditions: |
• | Determine the cause of the fouling before replacing the spark plugs. |
• | Inspect the spark plug boots for signs of arcing, cracks, carbon tracking, or damage. |
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Engine Cooling System
| Inspect the engine thermostat for proper operation and for correct heat range. Refer to
Thermostat Diagnosis
in Engine Cooling.
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Engine Mechanical
| Inspect for excessive crankshaft endplay that will cause the crankshaft position (CKP) sensor reluctor wheel to move out of alignment with the CKP sensor. Refer to
Crankshaft and Bearing Cleaning and Inspection
in
Engine Mechanical. This could result in any of the following conditions:
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Additional Inspections
| Inspect the generator output voltage. Refer to
Charging System Test
in Engine Electrical.
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