P1200how we solve indigo diacore
DTC P1200 - lnjector control circuit
The PCM has the ability to detect a misfire by monitoring the 3X reference and camshaft position input signals from the Ignition Control Module. The PCM monitors crankshaft speed variations (reference period differences) to determine if a misfire is occurring. If 2 percent or more of all cylinder firing events are misfires, emission levels may exceed mandated standards. The PCM determines misfire level based on the number of misfire events monitored during a 200 engine revolution test sample. The PCM continuously tracks 16 consecutive 200 revolution test samples. If 11 or more misfires are detected during any 5 of the 16 samples, DTC P0300 will set. If the misfire is large enough to cause possible three-way catalytic converter damage, DTC P0300 may set during the first 200 revolution sample in which the misfire was detected. In the case of a catalyst damaging misfire, the Malfunction Indicator Lamp (MIL) will flash to alert the vehicle operator of the potential of catalyst damage.
CONDITIONS FOR SETTING THE DTC
* No Vehicle Speed Sensor (VSS), Transaxle, Throttle Position (TP) sensor, Fuel trim, Fuel injector circuit, Engine Coolant Temperature (ECT) sensor, Crankshaft Position (CKP) sensor, Camshaft Position (CMP) sensor, or Mass Air Flow (MAF) sensor DTC(s) set.
* Engine speed between 450 and 5800 RPM.
* System voltage between 9 and 16 volts.
* The ECT indicates an engine temperature between -7 degrees C (19 degrees F) and 120 degrees C (248 degrees F).
* Throttle angle steady.
* The PCM is detecting a crankshaft RPM variation indicating a misfire sufficient to cause three-way catalytic converter damage or emissions levels to exceed mandated standard.
ACTION TAKEN WHEN THE DTC SETS
* If the misfire level is non-catalyst damaging, the PCM will illuminate the MIL during the second key cycle in which the DTC sets.
* If the misfire is severe enough to cause possible catalyst damage, the PCM will immediately flash the MIL while the misfire remains at catalyst damaging levels.
* The PCM will disable Torque Converter Clutch (TCC) operation.
* The PCM will store conditions which were present when the DTC set as Freeze Frame and Fail Records data.
CONDITIONS FOR CLEARING THE MIL/DTC
* The PCM will turn the MIL OFF during the third consecutive trip in which the diagnostic has been run and passed.
* The history DTC will clear after 40 consecutive warm-up cycles have occurred without a fault.
* The DTC can be cleared by using the scan tool Clear Info function or by disconnecting the PCM battery feed.
The scan tool provides information that can be useful in identifying the misfiring cylinder. If the DTC P0300 is currently stored as DTC status Failed Since Code Clear, the misfire history counters (Misfire Hist #1 - #6) will still contain a value that represents the level of misfire detected on each cylinder. The scan tool displayed misfire counter values (Misfire Hist. #1 through #6) can be useful in determining whether the misfire affects a single cylinder, a cylinder pair (cylinders that share an ignition coil-1/4, 2/5, 3/6), or is random. If the largest amount of activity is isolated to a cylinder pair, check for the following conditions:
* Secondary Ignition Wires.
Check the secondary wires associated with the affected cylinder pair for disconnected ignition wires or for excessive resistance. The wires should measure under 30,000 ohms (30 K ohms). Replace any wires with excessive resistance.
* Damaged Or Faulty Ignition Coil.
Check for cracks, carbon tracking or other damage. Also check coil secondary resistance. Secondary resistance should be between 5000 ohms and 8000 ohms (5 K ohms and 8 K ohms). Replace any faulty coil(s). Refer to Ignition Control Module.
* Substitute a Known Good Coil.
Switch ignition coils and retest. If the misfire follows the coil, replace the ignition coil.
If the misfire is random, check for the following conditions
* System Grounds.
Ensure all connections are clean and properly tightened. Refer to Ground Distribution in Electrical Diagrams.
* Mass Air Flow sensor.
A Mass Air Flow (MAF) sensor output that causes the PCM to sense a lower than normal air flow will cause a lean condition. Try operating the vehicle within the fail records conditions with the MAF sensor disconnected. If the lean or misfiring condition is not present with the MAF sensor disconnected, replace the MAF sensor. Refer to MAF Sensor.
* Damaged accessory drive belt or driven accessory.
A damaged serpentine belt or belt driven accessory can cause engine load variations sufficient to set a misfire DTC.
* Vacuum Leaks.
Vacuum leaks that cause intake air to bypass the MAF sensor will cause a lean condition. Check for the following conditions:
- Disconnected or damaged vacuum hoses. Refer to Emission Hose Routing Diagram.
- Incorrectly installed or faulty crankcase ventilation valve. Refer to Positive Crankcase Ventilation Valve
- Vacuum leaks at the throttle body, EGR valve, and intake manifold mounting surfaces.
* Fuel Pressure.
Perform a fuel system pressure test. A faulty fuel pump, plugged filter, or faulty fuel system pressure regulator will contribute to a lean condition. Refer to Fuel System Pressure Test. See: Computers and Control Systems > Component Tests and General Diagnostics > Fuel System Pressure Test
* Fuel injector(s). Go to Fuel Injector Coil Test. See: Computers and Control Systems > Component Tests and General Diagnostics > Fuel Injector Coil Test
* Contaminated Fuel. Go to Alcohol/Contaminants-in-Fuel Testing Procedure. See: Fuel Delivery and Air Induction > Testing and Inspection
* EGR System.
Check for leaking valve, adapter, or feed pipes which will contribute to a lean condition or excessive EGR flow.
* Extended Idle.
Excessive open loop operation caused by extended idling or short trip driving may leave deposits on the heated oxygen sensors. The deposits cause oxygen sensors to respond slowly to exhaust oxygen content, affecting fuel control and causing a misfire to be indicated at idle. This condition is not permanent. To determine if this condition is causing the DTC P0300 to be set, review the freeze frame and fail records data for DTC P0300. If the DTC P0300 occurs at high engine speeds, the condition described above did not cause the DTC P0300 to set. If the DTC P0300 occurs at idle or very low engine speeds and at engine coolant temperatures below 80 degrees C (176 degrees F), the condition described above is very likely the cause of the DTC P0300 being set. The deposits on the heated oxygen sensors can be eliminated by operating the vehicle fully warm at mass air flows above 15 gm/s.
Important: If the level of misfire was sufficient to cause possible catalyst damage (if the MIL was flashing), ensure that the DTC P0420 test is completed and passed after verifying the misfire repair.
Reviewing the Fail Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to be set occurs. This may assist in diagnosing the condition.
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Aug 13, 2012 |
Tata Indigo Cars & Trucks