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
|
| • | Check the powertrain control module (PCM) grounds for being clean, tight,
and in the proper locations. Refer to
Engine Controls Schematics
. |
| • | Be sure 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
|
| • | Check the heated oxygen sensors (HO2S). The HO2S should respond quickly
to different throttle positions. If they do not, check 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 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 - 8.1L. |
| • | Check the mass air flow (MAF) sensor connections. Repair or replace terminals.
Refer to
Connector Repairs
in Wiring Systems. |
|
Fuel System
|
| • | Check that each injector harness is connected to the correct injector
or cylinder according to the firing order 1-8-7-2-6-5-4-3.
Relocate injector harnesses as necessary. |
| • | Check the items that cause an engine to run rich long term fuel trim near-13 percent.
For a rich condition, refer to
DTC P0132 or P0152
. |
| • | Check the items that can cause an engine to run lean long term fuel trim
near 24 percent. For a lean condition, refer to
DTC P0131 or P0151
. |
|
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 gauge 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
| Check engine mechanical for the following:
| • | Sticking or leaking valves |
|
Additional Checks
| Check vacuum hoses for splits, kinks, and proper connections and routing as
shown on Vehicle Emission Control Information label.
|
