Surges and/or Chuggles

DEFINITION
Engine power variation under steady throttle or cruise. Feels like the vehicle speeds up and slows down with no change in the acceleration pedal.

PRELIMINARY CHECKS
^ Perform the careful visual/physical checks as described in "PRELIMINARY CHECKS". Preliminary Checks
^ Be sure driver understands transaxle torque converter clutch, and A/C compressor operation as explained in the owner's manual.
^ Check for Service Bulletin updates.
^ Inspect ECM grounds for being clean, tight and in their proper location.

SENSORS
^ Check Heated Oxygen Sensor (H02S). The HO2S should respond rapidly to the varying throttle positions. After the HO2S has reached operational temperature, the voltage should change quickly, and can go as high as 1 volt and as low as O.1 volt in less than a second. If this response time is slow or voltage is at a steady level, the H02S should be checked for silicone, glycol or other contamination. The HO2S may have a white powdery coating (silicone contamination) or a green coating (glycol contamination) that would result in a false signal voltage to ECM, and may lead to a driveability complaint.

IGNITION SYSTEM
^ Check for proper ignition voltage output using spark tester (ST-125) J-26792 or equivalent.
^ Check Spark plugs. Remove spark plugs, check for wet plugs, cracks, wear, improper gap, burned electrodes, or heavy deposits. Repair or replace as necessary. Also check the condition of electronic ignition and spark plug wires.

FUEL SYSTEM

NOTE: To determine if the condition is caused by a rich or lean system, the vehicle should be driven at the speed of the complaint. Monitoring block learn will help identify a problem.

- Lean- Block learn above 142. Refer to "Diagnostic Aids" on facing page of diagnostic trouble code 44. DTC 44
- Rich - Block learn below 118. Refer to "Diagnostic Aids" on facing page of diagnostic trouble code 45. DTC 45

Check:
^ Fuel pressure, Refer to "DIAGNOSTIC CHARTS / A-CHARTS / CHART A-7". A - Charts
^ Check in-line fuel ffilter Replace if dirty or plugged.
^ Check for contaminated fuel.

ADDITIONAL CHECKS
^ Check Engine control module grounds for being clean, tight and in their proper location.

^ Check Exhaust gas recirculation - There should be no exhaust gas recirculation at idle. Refer to CHART C-7A.C-7A ~ EGR System Check
^ Check vacuum lines for kinks or leaks.
^ Check alternator output voltage - Repair if less than 9 or more than 16 volts.