Hyundai Repair Questions? Ask a Mechanic for Answers ASAP
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1- check the wiring harness at the injectors ,wiggle the harness see if engine idle changes
2- P0300 is random multiple misfire ,this where you need to start
3- The CKP (crank position sensor ) will be the trigger so & is common failure
4- what is the mileage on it
5- the oxygen sensor at 0 not what you want to see
6- what are the long term fuel trims & short term fuel trims at idle ?
Please let me know
ASE Certified Technician
Engine Engine Control - P0300 Random/Multiple Cylinder Misfire Detected - General Information Component Location
General Description Misfires can be caused by lack of combustion in a cylinder due to absence of spark, poor fuel metering, poor compression, or many other causes. Even a small number of misfires may result in excessive exhaust emissions due to the unburned mixture. Increased misfire rates cause damage to the catalytic converter. The ECM monitors the crankshaft speed variation to determine if any misfiring generated. The ECM identifies the specific cylinder in which the misfire has occurred and counts individual misfire events by monitoring changes in the crankshaft rotation for each cylinder. A random misfire indicates two or more cylinders are misfiring. DTC Description The ECM measures reference event times and calculates the positive and negative acceleration of the crank wheel to determine whether a misfire has occurred. When the rate of misfire exceeds a threshold where the catalyst reaches a temperature where permanent damage can occur, to the point that tail pipe emissions reach 1.5 times the tailpipe standard or where a cylinder misfire cause a loss of torque produced from that cylinder. ECM sets this DTC. In case that misfire affects Catalyst damage, MIL (Malfunction Indicating Lamp) will be illuminating and blinking at 1HZ frequency. However, In case of Individual and Emission damaging misfire, MIL will be turned on when the malfunction is detected.