Engine Controls - 1.6L (L91) Troubleshooting & Diagnosis): Troubleshooting: Surges/Chuggles

Surges/Chuggles

Checks	Action
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 position.
Preliminary	Refer to Important Preliminary Checks Before Starting in Symptoms - Engine Controls . Search for bulletins. Verify that the engine control module (ECM) grounds are clean, tight, and in the correct locations. Make sure the driver understands the operation of the transmission torque converter clutch (TCC) and the A/C compressor operation as explained in the owner's manual. Inform the customer how the TCC and the A/C clutch operate.
Sensor/System	Test the heated oxygen sensors (HO2S). The HO2S should respond quickly to a change in throttle position. If the HO2S do not respond to different throttle positions, inspect for contamination from fuel, silicon, or the incorrect use of RTV sealant. The sensors may have a white powdery coating and result in a high, but false, signal voltage, which gives a rich exhaust indication. The ECM reduces the amount of fuel delivered to the engine, causing a driveability condition.
Fuel System	Test for incorrect fuel pressure. Refer to Fuel System Diagnosis . Test for a contaminated fuel condition. Refer to Alcohol/Contaminants-in-Fuel Diagnosis (W/O Special Tool) or Alcohol/Contaminants-in-Fuel Diagnosis (W/Special Tool) . Verify that the fuel injector harness is connected to the correct injector/cylinder according to the firing order. Test the fuel injectors. Refer to Fuel Injector Coil Test . Test or inspect items that can cause an engine to run rich. For a rich condition, refer to DTC P0172 . Test or inspect items that can cause an engine to run lean. For a lean condition, refer to DTC P0171 .
Ignition System	Wet down the secondary ignition system with water from a spray bottle. Wetting down the secondary ignition system may help locate damaged or deteriorated components. Look/listen for arcing or misfiring as the water is applied. Test the ignition voltage output with the J 26792 Spark Tester. Refer to Electronic Ignition (EI) System Diagnosis . Remove the spark plugs and inspect for the following: Incorrect heat range Wet plugs Cracks Excessive wear Improper gap Burned electrodes Heavy deposits Refer to the following procedures: SPARK PLUG INSPECTION Spark Plug Replacement Ignition System Specifications If the spark plugs are fouled by gas, coolant, or oil, determine the cause before replacing the plugs. Refer to the following procedures: For diagnosis of a rich condition, refer to DTC P0172 . For diagnosis of coolant or oil fouled spark plugs, refer to Loss of Coolant in Engine Cooling or Symptoms - Engine Mechanical in Engine Mechanical - 1.6L (L91). Inspect the spark plug wires for damage. Refer to SPARK PLUG WIRE INSPECTION . Inspect the ignition coil for cracks or carbon tracking.
Additional Checks	Inspect the vacuum hoses for splits or kinks. Verify that the routing and connections are as shown on the Vehicle Emission Control Information label. Refer to Emission Hose Routing Diagram . Test the transmission torque converter clutch (TCC). A TCC applying too soon can cause the engine to surge or chuggle. Refer to Symptoms - Automatic Transmission in Automatic Transmission - Aisin (81-40LE). Test the A/C clutch. Refer to Symptoms - HVAC Systems - Manual in HVAC Systems - Manual.