Surges and/or Chuggles Symptom
Checks
| Action
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DEFINITION: The engine has a power variation under a steady throttle or cruise.
The vehicle feels as if it speeds up and slows down with no change in the accelerator
pedal.
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Preliminary Checks
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• | Be sure the driver understands the A/C compressor operation. |
• | Use a scan tool to make sure the reading of VSS matches vehicle speedometer.
This excludes vehicles with electronic transmissions where some variation between
VSS and the speedometer is normal. |
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Sensor Check
| Check the Oxygen Sensor (O2S) Sensor 1 performance. Refer to DTC P0130
through DTC P0141 Diagnostic Aids.
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Fuel System Checks
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• | Check if a Rich or Lean system can cause the condition. Drive the vehicle
at the speed of the complaint. Monitoring the Fuel Trim may help identify the problem. |
- | Lean -- The Long Term Fuel Trim will be greater than 20%. Refer to
Diagnostic Aids. |
- | Rich -- The Long Term Fuel Trim will be less than -20%. Refer
to Diagnostic Aids. |
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Ignition System Checks
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• | Check for the proper secondary voltage output with a spark tester (J 26792
or equivalent). |
• | Check the spark plugs for any of the following conditions: |
- | Wet (fuel fouled) plugs. |
- | A terminal screw that is bent or loose (rotate and pull). |
- | A ceramic insulator that has cracks, carbon tracking or deposits (red
or black dust) |
- | A tip insulator that has cracks, carbon tracking, deposits (oil, carbon,
glazing, fuel additive), or is loose (rattles). |
- | A center electrode that is loose (wiggles side to side) |
- | An incorrect spark plug gap that is too large or too small. |
- | Platinum pads that are missing. |
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Additional Checks
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• | Inspect for the correct operation of the exhaust gas recirculation (EGR)
system. An inoperative EGR system can cause excessive detonation that results in retarded
ignition timing. Excessive EGR flow can cause incorrect air fuel ratios resulting
in inefficient combustion.. Refer to
Exhaust Gas Recirculation (EGR) System Diagnosis. |
• | Check the PCM grounds for being clean, tight, and in their proper locations.
Refer to PCM Wiring Diagrams. |
• | Check the generator output voltage. |
• | Check the vacuum lines and hoses for kinks or leaks. Refer to the Vehicle
Emission Control Information label. |
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