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.
|
Preliminary
|
| • | Search for service bulletins. |
| • | Be sure the driver understands the transmission torque converter
clutch, and the A/C compressor operation as explained in the owners manual.
Inform the customer how the TCC and the A/C clutch operates. |
| • | Check the PCM grounds for being Clean, tight and in their proper
location. |
|
Sensor/System
|
| • | Check the Oxygen sensor (O2S 1) and the Heated Oxygen Sensor (HO2S
2). The O2S 1 and HO2S 2 should respond quickly to different throttle positions.
If not, check the O2S 1 and the HO2S 2 for silicon or other contaminants
from fuel or the use of improper RTV sealant. The sensors may have a white
powdery coating. Silicon contamination causes a high but false O2S 1 and
HO2S 2 signal voltage (rich exhaust indication). The PCM will reduce the
amount of fuel delivered to the engine, causing a severe driveability problem.
Refer to Oxygen sensor and the Heated Oxygen Sensor in
Information Sensors/Switches Description
. |
| • | Check for proper operation of the MAP sensor. |
| • | Check for proper operation of the TP sensor. |
| • | Check for proper operation of the ECT sensor. |
|
Fuel
System
|
| • | Check for contaminated fuel. Refer to Alcohol/Contaminants-in-Fuel Diagnosis
. |
| • | Check the fuel filter for being plugged or restricted. |
| • | Ensure each injector harness is connected to the correct injector/cylinder.
Refer to the Engine Controls Wiring Diagrams. |
| • | Check items which can cause an engine to run rich (long term fuel
trim is significantly in the negative range). Refer to Diagnostic Aids for
DTC P0172 Fuel Trim System Rich
. |
| • | Check items that can cause an engine to run lean (long term fuel
trim is significantly in the positive range). Refer to Diagnostic Aids for
DTC P0171 Fuel Trim System Lean
. |
|
Ignition
System
|
| • | Check for proper ignition voltage output with spark tester J-26792
or equivalent. |
| • | Check the spark plugs for the following conditions: |
| - | Check for wet or fuel fouled spark plugs. |
| - | Check for cracks on the spark plugs. |
| - | Check for improper spark plug gap. |
| - | Check for burned electrodes or heavy deposits. |
| • | If the spark plugs are fuel or oil fouled, the cause of the fouling
must be determined before replacing the spark plugs. |
| • | Check the Ignition Control Module (ICM) for proper ground connection. |
| • | Check the ignition coils for cracks or carbon tracking. |
| • | Check the spark plug wires forproper resistance and condition. |
|
Additional
Checks
|
| • | Check for proper operation of the TCC. Refer to Automatic Transmission Diagnosis
. |
| • | Check the exhaust system for a possible restriction: |
| - | Inspect the exhaust system for damaged or for possible collapsed
pipes. |
| - | Inspect the muffler for heat distress or for possible internal
failure. |
| • | Check the vacuum lines for kinks or leaks. |
| • | Check the generator output voltage. Repair the generator if the
output voltage is less than 11 volts or more than 16 volts. |
| • | If all procedures have been completed and no malfunctions have
not been found, review and inspect the following items: |
| - | Visually and physically inspect all electrical connections within
the suspected circuit and/or systems. |
|
