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Feb 5, 2010 - Uploaded by Scotty Kilmer
Scotty Kilmer, mechanic for the last 46 years and counting, shows how to fix your car if the check engine light ...
P0300 Diagnostic Code - Random Misfire Technical Description Random/Multiple Cylinder Misfire Detected What does that mean? Basically this means that the the car's computer has detected that not all of the engine's cylinders are firing properly. A P0300 diagnostic code indicates a random or multiple misfire. If the last digit is a number other than zero, it corresponds to the cylinder number that is misfiring. A P0302 code, for example, would tell you cylinder number two is misfiring. Unfortunately, a P0300 doesn't tell you specifically which cylinder(s) is/are mis-firing, nor why. Symptoms Symptoms may include: the engine may be harder to start the engine may stumble / stumble, and/or hesitate other symptoms may also be present Causes A code P0300 may mean that one or more of the following has happened: Faulty spark plugs or wires Faulty coil (pack) Faulty oxygen sensor(s) Faulty fuel injector(s) Burned exhaust valve Faulty catalytic converter(s) Stuck/blocked/leaking EGR valve / passages Faulty camshaft position sensor Defective computer Possible Solutions If there are no symptoms, the simplest thing to do is to reset the code and see if it comes back. If there are symptoms such as the engine is stumbling or hesitating, check all wiring and connectors that lead to the cylinders (i.e. spark plugs). Depending on how long the ignition components have been in the car, it may be a good idea to replace them as part of your regular maintenance schedule. I would suggest spark plugs, spark plug wires, distributor cap, and rotor (if applicable). Otherwise, check the coils (a.k.a. coil packs). In some cases, the catalytic converter has gone bad. If you smell rotten eggs in the exhaust, your cat converter needs to be replaced. I've also heard in other cases the problems were faulty fuel injectors. Random misfires that jump around from one cylinder to another (read: P030x codes) also will set a P0300 code. The underlying cause is often a lean fuel condition, which may be due to a vacuum leak in the intake manifold or unmetered air getting past the airflow sensor, or an EGR valve that is stuck open. It is helpful to have access to a factory service manual and an advanced scan tool to properly diagnose a random misfire DTC. P0300 Diagnostics Video Here is a helpful video that may assist you in learning more, diagnosing, and repairing your P0300 DTC. This video is intended for auto repair professionals but could be helpful to DIYers. It shows use of an advanced OBD-II scan tool during diagnostic steps:
the fuel smell is from unburnt fuel in the cylinders not firing , i'd have to start with reading the OBD codes to help narrow down the component/s at fault but at a guess i'd think the ign coils are at fault but the OBD will pinpoint the issue
A P0300 code indicates random, multiple misfires were detected. You eliminated the possibility of ignition system faults by replacing the ignition module, the coils, and the spark plugs (unless the replacement part(s) were no good). However you did not mention the ignition wires which are another probable cause. In addition, there could be vacuum leaks due to damaged hoses or improper routing. Consider also fuel contamination or a problem with the fuel system.
Im assuming your asking about the ODB-II codes, this code,P0300 Random/Multiple Cylinder Misfire Detected. A P0300 diagnostic code indicates a random or multiple misfire. If the last digit is a number other than zero, it corresponds to the cylinder number that is misfiring. A P0302 code, for example, would tell you cylinder number two is misfiring. Unfortunately, a P0300 doesn't tell you specifically which cylinder(s) is/are mis-firing, nor why. Here are a few things that could be the cause.
CODE PO300 - RANDOM MISFIRE DETECTED. POSSIBLE CAUSES ENGINE HAS A MECHANICAL FAULT.CLOGGED OR FAULTY FUEL INJECTORS.FUEL PRESSURE TOO LOW OR HIGH FUEL SUPPLY CONTAMINATED.EVAP CANISTER FUEL SOAKED.EGR VALVE IS STUCK OPEN OR THE PCV VALVE SYSTEM HAS A VACUUM LEAK.COULD HAVE FAULTY IGNITION COIL OR BAD SPARK PLUG. MAF SENSOR CONTAMINATED IT CAN CAUSE VERY LEAN FUEL CONDITIONS. CODE PO316 - MISFIRE IN THE FIRST 1000 REVOLUTIONS
so its got a misfire and quickest way out here to avoid a expensive garage visit is to change plugs and Ht leads and see what happens ,HT leads is proper english for fire wires by the way ,see iam learning american ---slowly---
OBD II 300 Random/Multiple Cylinder Misfire Detected
When the misfire monitor detects a misfire, it will trigger the check engine light with the specific cylinder number as the last digit in the P030X code. For instance cylinder 1 misfire is P0301, cylinder 2 is P0302 etc. In this case we have either multiple cylinders misfiring, or the computer simply can't determine the specific cylinder, and as such we are left with the P0300 in computer memory.
Fuel injectors, related wiring, sensors and computer issues Running out of gas, or poor fuel quality Evaporative emissions system (EVAP) concerns: fuel vapors leaking into engine Incorrect Fuel Pressure EGR system concerns: leaking EGR valve or restricted ports Base engine concerns: low compression, valve train problems and timing issues Ignition system concerns including, but not limited to: Faulty spark plugs Faulty coil or related wiring Ignition module or related wiring issues Ignition related sensor faults or wiring issues