Surges/Chuggles

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

PRELIMINARY CHECKS
^ Perform the visual and physical checks as described in Preliminary Checks.
^ Be sure driver understands transmission torque converter clutch, and A/C compressor operation as explained in the owner's manual.

SENSORS
Check: Heated Oxygen Sensors (HO2S). The HO2S should respond quickly to different throttle position, if they don't, check the HO2S for silicon or other contaminates from fuel, or 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 Powertrain Control Module (PCM) will then reduce the amount of fuel delivered to the engine, causing a severe driveability problem.

FUEL SYSTEM
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 long term fuel trim will help identify a problem.

Lean Condition
A lean condition is present when the long term fuel trim value reads near 160. Refer to "Diagnostic Aids" located in Diagnostic Charts / Diagnostic Trouble Code Charts 44 and 64. Testing and Inspection

Rich Condition
A rich condition is present when the long term fuel trim value reads near 108. Refer to "Diagnostic Aids" located in Diagnostic Charts / Diagnostic Trouble Code Charts 45 and 65. Testing and Inspection

Check: Fuel pressure. Refer to Chart Diagnostic Charts / A-7 Fuel System Diagnosis. Related Tests, Information and Procedures

Check: In-line fuel filter. Replace if dirty or plugged.

IGNITION SYSTEM
Check: For ignition misfire. Refer to Diagnostic Charts / Chart C-4B Misfire Check. Chart C-4B Misfire Check

Check: For proper ignition voltage output using spark tester J26792 (ST 125).

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 condition of distributor cap, rotor and ignition wires.

Check: Distributor vent system. Refer to Diagnostic Charts / Chart C-4C Distributor Vent System Check. Chart C-4C Distributor Vent System Check

ADDITIONAL CHECKS
Check: Injector harness locations. Make sure each injector harness is connected to the correct injector/cylinder according to the firing order (firing order 1-8-4-3-6-5-7-2).

Check: PCM grounds for being clean, tight and in their proper location.

Check: Mass Air Flow (MAF) connections.

Check: Vacuum lines for kinks or leaks.

Check: Exhaust Gas Recirculation (EGR) - There should be no EGR at idle. Refer to Diagnostic Charts / Chart C-7 EGR System Check. Chart C-7 Exhaust Gas Recirculation (EGR) System Check

Check: Generator output voltage. Repair if less than 9 volts or more than 16 volts.

Check: PROM Calibration I.D. for most current and/or incorrect software. Refer to PROM - Programmable Read Only Memory for calibration information.