Surges/Chuggles. Geo Prizm 1996

For 1990-2009 cars

#### Surges and/or Chuggles Symptom

Checks | Action
--- | ---
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.

Preliminary Checks

• | Refer to Powertrain On Board Diagnostic (OBD) System Check.

• | Refer to Symptoms.

• | 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.

Sensor Check | Check the Oxygen Sensor (O2S) Sensor 1 performance. Refer to DTC P0130 through DTC P0141 Diagnostic Aids.

Fuel System Checks

• | 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.

• | Check the fuel injectors. Perform the Fuel Injector Coil Test Procedure and the Fuel Injector Balance Test Procedure. Refer to Fuel Injector Solenoid Coil Test - Engine Coolant Temperature Between 10-35 Degrees C (50-95 Degrees F) and Fuel Injector Balance Test.

• | Check the fuel pressure while the condition exists. Refer to Fuel System Diagnosis.

Ignition System Checks

• | 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.

Additional Checks

• | 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.