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George H.
George H., Hyundai Technician
Category: Hyundai
Satisfied Customers: 2093
Experience:  Hyundai Gold certified, ASE Master tech 15+ years
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On a 2010 Genesis 3.8l we have p0300, p0303 and p0305. The

Customer Question

On a 2010 Genesis 3.8l we have p0300, p0303 and p0305. The scanner shows no injector pulse on the two cylinders. It is showing the p0301 in pending. I thinking I need to scope the crank sensor for trigger.
JA: Does the vehicle stall at low speeds? Does it sputter?
Customer: It has not stalled. It runs very rough at idle and low speed.
JA: Are you fixing your Genesis yourself? What have you tried so far?
Customer: What 86k miles, we started with plugs and the 2 coils.
JA: Anything else you want the mechanic to know before I connect you?
Customer: The 02 sensors stay at 0 volts all the time.
Submitted: 11 months ago.
Category: Hyundai
Expert:  Chad Farhat replied 11 months ago.

Hi, I'm Chad. Welcome to JustAnswer. I'm reviewing your question and I will be posting your reply ASAP.

Customer: replied 11 months ago.
Expert:  Chad Farhat replied 11 months ago.

hey how are you '

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

Thank You

Chad Farhat

ASE Certified Technician

Expert:  Chad Farhat replied 11 months ago.

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.