2010 Cadillac Truck Escalade RWD V8-6.2L Page 1985
- Cylinder 8 Misfire Detected
Circuit/System Description
The engine control module (ECM) uses information from the crankshaft position (CKP) sensor in order to determine when an engine misfire is
occurring, and uses information from the camshaft position (CMP) sensor in order to determine which cylinder is misfiring. By monitoring
variations in the crankshaft rotation speed for each cylinder, the ECM is able to detect individual misfire events. If the ECM detects a misfire rate
sufficient to cause emission levels to exceed mandated standards, DTC P0300 sets. Under certain driving conditions, a misfire rate can be high
enough to cause the catalytic converter to overheat, possibly damaging the converter. The malfunction indicator lamp (MIL) will flash ON and OFF
when catalytic converter overheating conditions are present and DTC P0300 is set. DTCs P0301-P0308 corresponds to cylinders 1-8. If the ECM is
able to determine that a specific cylinder is misfiring, the DTC for that cylinder will also set.
Conditions for Running the DTC
* DTCs P0010, P0011, P0016, P0068, P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0120, P0122, P0123,
P0220, P0222, P0223, P0335, P0336, P0606, P0641, P0651, P1516, P2101, P2120, P2122, P2123, P2125, P2127, P2128, P2135, P2138, and
P2176 are not set.
* When DTC P0315 is set, the engine speed must be more than 1,000 RPM.
* Engine run time is more than 2 crankshaft revolutions.
* The engine speed is between 375-5,600 RPM.
* The ignition voltage is between 9-18 volts.
* The engine coolant temperature (ECT) is between -7 and +130掳C (+19 and +266掳F).
* When the startup ECT is colder than -7掳C (+19掳F), this diagnostic will be delayed until the ECT is warmer than +21掳C (+69掳F).
* The fuel level is more than 10 percent.
* The ECM is not in fuel shut-off, or decel fuel cut-off mode.
* The electronic brake control module (EBCM) and the traction control system (TCS) are not active or detecting rough road.
* An automatic transmission shift with a throttle position more than 95 percent is not occuring.
* The power management is not active.
* Excessive drive wheel slip is not detected.
* The power take-off (PTO) is disabled, where applicable.
* The cylinder deactivation is not in progress, where applicable.
* DTCs P0300-P0308 run continuously when the above conditions are met.
Conditions for Setting the DTC
DTC P0300
The ECM is detecting a crankshaft speed change indicating a random misfire is occuring that exceeds mandated emission level standards or is at
catalytic converter damaging levels.
DTC P0301, P0302, P0303, P0304, P0305, P0306, P0307, or P0308
The ECM is detecting a crankshaft speed change indicating a single cylinder misfire is occuring that exceeds mandated emission level standards or
is at catalytic converter damaging levels.
Action Taken When the DTC Sets
* DTCs P0300-P0308 are Type B DTCs.
* When the MIL is flashing the fuel injector may be disabled for the misfiring cylinder to protect the catalytic converter.
* Depending on the conditions that set the DTC, the engine may go into Open Loop.
Conditions for Clearing the MIL/DTC
* DTCs P0300-P0308 are Type B DTCs.
* The DTC must run and pass under the same operating conditions that were present when the DTC failed.
Diagnostic Aids
* Ensure that each fuel injector is connected to the proper fuel injector harness connector.
* A misfire may only occur when the engine is operating under a load or when the engine is cold.
* A high resistance condition on any ignition control (IC) circuit can cause an engine misfire P0300-P0308 DTC to set without setting an IC
circuit P0351-P0358 DTC.
* This test procedure requires that the vehicle battery has passed a load test and is completely charged. Refer to Battery Inspection/Test (See:
Starting and Charging/Testing and Inspection/Component Tests and General Diagnostics/Battery Inspection/Test).
* A misfire DTC could be caused by an excessive vibration from sources other than the engine. Inspect the following for possible sources of
vibration:
- A tire or wheel that is out of round or balance
- Variable thickness brake rotors
- An unbalanced drive shaft
