Checks
| Action
|
DEFINITION: The engine makes a mild to severe pinging
noise, which is usually worse during acceleration. The engine makes
sharp metallic knocks that change with the throttle opening.
|
Preliminary Checks
|
| • | Search the service bulletins. |
|
Fuel System
|
| • | Check for conditions that can cause an engine to run lean, where
the long-term fuel trim is significantly in the positive range. Refer to Diagnostic
Aids for
DTC P0171
. |
|
Ignition System
|
| • | Check the knock sensor (KS) system for no retard timing. |
|
Engine Cooling System
| Check for obvious overheating problems,
including the following conditions:
| • | Restricted air flow to the radiator |
| • | Restricted water flow through the radiator |
| • | Inoperative electric cooling fan circuits |
| • | Incorrect thermostat operation |
The correct coolant solution should be a 50/50 mix of Dexcool® or
an equivalent mixture of antifreeze coolant and water. Refer to
Engine Overheating
in Engine Cooling.
|
Engine Mechanical
|
| • | Excessive oil in the combustion chamber. This condition can be
caused by leaking valve seals. Refer to
Oil Consumption Diagnosis
in Engine Mechanical 2.4L. |
| • | Excessive carbon buildup--Check the combustion chambers.
Clean the chambers with Top engine cleaner. Follow the instructions on the
can. |
| • | Incorrect basic engine parts. Inspect the following: |
| - | Other components, as applicable. |
|
Additional Checks
|
| • | Check for proper operation of the manifold absolute pressure (MAP)
sensor. Ensure that the MAP sensor is not out of range. |
| • | Check the park/neutral position (PNP) switch input with the vehicle
in drive, and with the gear selector in drive or in overdrive. |
| • | Check the torque converter clutch (TCC) operation. Applying the
TCC too soon can cause the engine to spark knock. Refer to
Road Test
for 4T40-E/4T45-E in Automatic
Transmission. |
| • | If the scan tool readings are normal, and if there are no engine
mechanical malfunctions, fill the fuel tank with a known quality gasoline
that has a minimum octane reading of 87. Re-evaluate the
vehicle performance. |
|
