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, indicating a rich exhaust indication. |
• | 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 the fuel filter for plugs or restrictions. |
• | Ensure that each injector harness is connected to the correct
injector/cylinder. Refer to
Engine Controls Schematics
in Engine Controls. |
• | Check the items which can cause an engine to run rich, for example,
the long term fuel trim is significantly in the negative range. Refer to Diagnostic
Aids for
DTC P0172 Fuel Trim System Rich
. |
• | Check the items that can cause an engine to run lean, for example,
the 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 J 26792
spark tester 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, determine the cause
of the fouling before replacing the spark plugs. |
• | Check the ICM for proper ground connection. |
• | Check the ignition coils for cracks or carbon tracking. |
• | Check the spark plug wires for proper resistance and condition. |
|
Additional Checks
|
• | 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 for possible plugged three-way catalytic converter. Refer
to
Restricted Exhaust
or Exhaust
System. |
• | 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
been found, review and inspect the following items: |
- | Visually and physically inspect all electrical connections within
the suspected circuit and/or systems. |
|