Inspections
| 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
|
| • | Ensure that the driver understands the operation of the transmission
torque converter clutch (TCC) and A/C compressor operation as explained in the
owners manual. Inform the customer how the TCC and the A/C clutch operates. |
|
Sensor/System
|
| • | Inspect the heated oxygen sensors (HO2S). The HO2S should respond quickly
to different throttle positions. If they do not, inspect the HO2S for silicon or
other contaminates from fuel or the 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. For more
information, refer to
Oil Consumption Diagnosis
in Engine Mechanical. |
| • | Inspect the mass air flow (MAF) sensor connections. Repair or replace
terminals. Refer to
Connector Repairs
in
Wiring Systems. |
|
Fuel System
|
| • | Verify that each injector harness is connected to the correct injector
or cylinder. Relocate injector harnesses as necessary. |
| • | Inspect the following that may cause the engine to run rich: |
Notice: Refer to Heated Oxygen and Oxygen Sensor Notice in the Preface section. | - | Water intrusion in the HO2S connector |
| - | Engine oil contaminated by fuel |
| - | An evaporative emission (EVAP) canister purge condition |
| - | Vacuum hoses for splits, kinks and proper connections |
| • | Inspect the following that may cause the engine to run lean: |
Notice: Refer to Heated Oxygen and Oxygen Sensor Notice in the Preface section. | - | Water intrusion in the HO2S connector |
| - | An exhaust leak between the HO2S and the engine--Refer to
Exhaust Leakage
in Engine Exhaust. |
| - | Vacuum hoses for splits, kinks and proper connections |
|
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 and listen for arcing or misfiring as you apply the water. |
| • | An improper spark plug gap will cause a driveability problem. Gap the
spark plugs using a wire gage gap tool. Refer to
Spark Plug Replacement
. |
| • | Determine the cause of the fouling before replacing the spark plugs
if the spark plugs are gas, coolant, or oil fouled. Refer to
Spark Plug Inspection
for diagnosis of fouled spark plugs. |
| • | Monitor the Misfire Current Counters while driving the vehicle in the
conditions that the misfire occurred. If a cylinder can be located with a misfire,
refer to
Electronic Ignition (EI) System Diagnosis
for diagnosis. |
|
Engine Mechanical
| Test engine mechanical for the following:
| • | Sticking or leaking valves |
| • | Inspect for excessive crankshaft endplay that will cause the CKP sensor
reluctor wheel to move out of alignment with the CKP sensor. Refer to
Crankshaft and Bearing Cleaning and Inspection
in Engine
Mechanical - 8.1L. This could result in any of the following conditions: |
|
Transmission
| Inspect the following for proper operations:
|
Additional
|
| • | Inspect vacuum hoses for splits, kinks, and proper connections and routing
as shown on Vehicle Emission Control Information label. |
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