Refer to
Ignition Controls
.
System Description
The powertrain control module (PCM) monitors both the crankshaft and camshaft position in order to detect engine misfire. The PCM looks for the rapid decrease in crankshaft speed associated with engine misfire once every 100 camshaft revolutions. The PCM may require that several consecutive misfire conditions are detected before storing this DTC and illuminating the malfunction indicator lamp (MIL). Under light misfire conditions, the PCM may require more than one trip to set this DTC. Under severe misfire, the PCM flashes the MIL. A flashing MIL signals that a misfire capable of damaging the catalytic converter is detected. The torque converter clutch (TCC) is disabled momentarily to determine if the misfire was due to a rough road condition on vehicles with automatic transmission only.
Conditions for Running the DTC
| • | No active MAP DTCs |
| • | No active IAT DTCs |
| • | No active ECT DTCs |
| • | No active TP DTCs |
| • | No active oxygen sensor DTCs |
| • | No active fuel trim DTCs |
| • | No active CKP DTCs |
| • | No active KS DTCs |
| • | No active CMP DTCs |
| • | No active VSS DTCs |
| • | No active IAC DTCs |
| • | No active PCM memory DTCs |
| • | The engine speed is between 469 RPM and 5,906 RPM. |
| • | The battery voltage is between 9 volts and 17 volts |
| • | The engine coolant temperature (ECT) is between -7°C (20°F) and 123°C (254°F) |
| • | The engine has been running for more than 5 seconds |
| • | The fuel level is above 10 percent |
Conditions for Setting the DTC
The misfire total is more than 8 counts.
Action Taken When the DTC Sets
The malfunction indicator lamp (MIL) will illuminate if the fault is active within the same conditions for two out of eighty ignition cycles when there is misfire.
OR
The MIL will illuminate after two consecutive ignition cycles in which the diagnostic runs with the fault active.
OR
| • | The MIL will illuminate immediately and flash if a misfire is severe enough to cause catalyst damage. |
| • | The torque converter clutch (TCC) will disable whenever a misfire is being detected with or without a misfire DTC set, (automatic transmission only). |
| • | The PCM will record the operating conditions at the time the diagnostic fails. The Freeze Frame and Failure Records buffers will store this information. |
| • | A history DTC is stored. |
Conditions for Clearing the MIL/DTC
| • | The MIL will turn off after 3 consecutive ignition cycles in which the diagnostic runs without a fault. |
| • | A history DTC will clear after 40 consecutive warm-up cycles without a fault. |
| • | Use a scan tool to clear the DTCs. |
Diagnostic Aids
An intermittent DTC can also be the result of a defective reluctor wheel. Remove the crankshaft sensor and inspect the reluctor wheel through the crankshaft sensor mount hole. Inspect the porosity and the condition of the reluctor wheel.
Whenever the DTC is an intermittent, refer to Symptoms .
Perform the Fuel Injector Balance Test. Refer to Fuel Injector Balance Test .
Test Description
The numbers below refer to the step numbers on the diagnostic table:
| • | The wiring for proper connections, pinches or cuts. |
| • | The PCM grounds for being clean and tight. |
| • | The vacuum hoses for splits, kinks, and proper connections as shown on the vehicle emission information label. Inspect thoroughly for any type of leak or restriction. |
| • | Inspect the throttle body mounting area and intake manifold sealing surfaces for air leaks. |
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When all the accumulators indicate misfire, then the misfire is being caused by something that affects the entire engine.
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If the misfire is not present, operate the vehicle within the conditions recorded in the Freeze Frame Data in order to detect misfire. Depending on the engine load, the conditions may have to be maintained for up to 20 seconds. Whenever the misfire accumulators start to increment, then misfire is present. A history misfire counter will store the number of misfires that have occurred until the DTC is cleared.
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Test the fuel for contamination (water, alcohol, etc).
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Tests the ignition system voltage output by using a spark tester.
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Replace any spark plugs that are worn, cracked, or fouled. Refer to ignition system if any plugs are fouled or damaged due to an engine mechanical malfunction.
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Tests for voltage at the ignition feed circuit.
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A basic engine problem that affects all cylinders is the only possibility at this point (e.g. cam timing, throttle body leak, restricted air flow, etc.).
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Whenever the fuel injector driver circuit is shorted to ground, the lamp will be ON steady. When the driver circuit is shorted to voltage or open, the lamp will be OFF.
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Since the voltage is supplied to the fuel injector on a single circuit, the malfunction may only be a poor electrical connection or an open in the fuel injector electrical harness. An open before the harness may result in a Cranks But Will Not Run complaint.
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The replacement PCM must be programmed and the Crankshaft Position System Variation learn procedure must be performed.
Step | Action | Values | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||||||||
2 | Was DTC P0200 also set? | -- | ||||||||
Did you find and correct the condition? | -- | |||||||||
4 |
Are any misfire current counters incrementing? | -- | ||||||||
Was a misfire present in all cylinders? | -- | |||||||||
Are any misfire current counters incrementing? | -- | Go to Diagnostic Aids | ||||||||
7 |
Does the fuel pressure read within the specified range? | 284-325 kPa (41-47 psi) | Go to Fuel System Diagnosis | |||||||
Test the fuel for contamination. Refer to Alcohol/Contaminants-in-Fuel Diagnosis . Is the fuel OK (uncontaminated)? | -- | |||||||||
9 | Replace the contaminated fuel. Did you complete the replacement? | -- | -- | |||||||
Was spark observed on all four spark plug wires? | -- | |||||||||
Did you find and correct the condition? | -- | |||||||||
Does the fuel injector test lamp blink? | -- | |||||||||
13 | Perform the Fuel Injector Solenoid Coil Test - Engine Coolant Temperature Between 10-35 Degrees C (50-95 Degrees F) . Did you find a problem? | -- | ||||||||
Did you find and correct the condition? | -- | -- | ||||||||
15 |
Did the test lamp illuminate? | -- | ||||||||
16 | Replace any malfunctioning fuel injectors. Refer to Fuel Injector Replacement . Did you complete the replacement? | -- | -- | |||||||
17 | Test the affected fuel injector driver circuits for the following conditions:
Did you find a problem? | -- | ||||||||
Repair as necessary. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | -- | ||||||||
Repair the open in the ignition positive voltage circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | -- | ||||||||
20 | Measure the resistance of the spark plug wire that the spark plug tester did not spark with. Does the resistance measure less than the specified value? | 1,000 ohms/inch | ||||||||
21 |
Notice: Do not leave the jumper wire connected to the PCM IC circuit connector for longer than 5 seconds at a time. Failure to do so may damage the ignition coil and/or the Ignition Control Module. Does the spark tester spark when the test lamp is removed from the IC circuit? | -- | ||||||||
22 |
Did you find and correct the condition? | -- | ||||||||
23 |
Does the secondary coil resistance measure within the specified value? | 5,000-8,000 ohms | ||||||||
24 |
Did the test lamp blink while cranking the engine? | -- | ||||||||
25 |
Did you complete the repair? | -- | -- | |||||||
26 |
Did you find and correct the condition? | -- | ||||||||
|
Important:: The replacement PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Did you complete the replacement? | -- | -- | ||||||||
28 | Replace the spark plug wire. Refer to Spark Plug Wire Harness Replacement in Engine Electrical. Did you complete the replacement? | -- | -- | |||||||
29 | Replace the ignition coil. Refer to Ignition Control Module Replacement . Did you complete the replacement? | -- | -- | |||||||
30 |
Does the DTC reset? | -- | System OK |
