GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 1998 🢒 Metro 🢒 Engine 🢒 Engine Controls - 1.3L 🢒 Surges/Chuggles

Checks

Action

DEFINITION: The engine power output varies under a steady throttle or cruise. The vehicle seems to speed up and slow down with no change in the accelerator pedal position.

Preliminary Checks
    • Refer to Symptoms .
    • Educate the driver about normal A/C compressor operation.
    • Use a scan tool in order to verfy that the reading of VSS matches the reading of the vehicle speedometer. Vehicles with electronic transmissions are excluded because some variation between VSS readings and speedometer readings are considered normal.

Sensor Check
    • Check the performance of the MAP sensor. Refer to DTC P0106 Manifold Absolute Pressure (MAP) System Performance Diagnostic Aids.
    • Check the performance of the heated oxygen sensor (HO2S) sensor 1 and the HO2S 2. Refer to Diagnostic Aids in DTC P0131 through DTC P0141.
        Check the performance of the heated oxygen sensor (HO2S) sensor 1 and the HO2S 2. Refer to Diagnostic Aids in DTC P0131 through DTC P0141.
    • Check the CKP sensor engine reference signal with a scan tool. Observe the Engine Speed parameter while operating the engine at the speed of the concern. The scan tool should indicate steady and linear RPM readings while running. If the erratic values, such as sudden spikes or drops in engine speed are displayed, the engine reference signal is not stable enough for the engine to run properly. Check for a short to ground in the CKP sensor Ignition Reference Low circuit . A short to ground in the CKP sensor Ignition Reference Low circuit will cause a faulty engine reference signal to be sent to the PCM, but will not set a CKP sensor DTC (P0335).

Fuel System Checks
    • Determine whether a rich or lean fueling condition can cause the concern. Drive the vehicle at the speed of the concern. Monitor the Fuel Trim parameters on a scan tool in order to identify the fuel system status.
       - Lean -- The Long Term Fuel Trim will be approaching 20%. Refer to DTC P0171 Fuel Trim System Lean Diagnostic Aids.
       - Rich -- The Long Term Fuel Trim will be less than -20%. Refer to DTC P0172 Fuel Trim System Rich 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 Sequential Multiport Fuel Injector Balance Test .
    • Check the fuel pressure while the condition exists. Refer to Fuel System Diagnosis .
    • Check for contaminated fuel or inferior quality fuel. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .

Ignition System Checks
    • Check for adequate secondary ignition voltage with a J 26792 spark tester or an 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.

Additional Checks
    • Check the PCM grounds for being clean, tight, and in their proper locations. Refer to PCM Power and Ground electrical schematic.
    • Check the generator output voltage.
    • Check the vacuum lines and hoses for kinks or leaks. Refer to the Vehicle Emission Control Information label.
    • Check the Service Bulletins for any updates.