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Posted on May 16, 2011
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When i connect my detector to my computer it reads P0300 random/multiple cylinder misfire detected. The van runs really rough..almost like its not getting enough gas or its misfiring. Not sure if to start with the fuel pump or spark plugs or coils...any help would be greatly appreciated... tks, mario

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  • Expert 158 Answers
  • Posted on May 16, 2011
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Mar82is, Mario, Yes a PO300 code is for random misfires. This is an issue with the spark plugs, wires, and coils. What you should do is to pull all the wires, one at a time, and inspect the terminals that connect to the spark plugs and the coil. If they are corroded then replacing these will help to alleviate the problem. Also check the spark plugs. See if they are wet and smell like gas. If so then this will be one of the misfiring plugs. A properly firing spark plug will have a gray color to them. If they are black and sooty then you should replace them. To check the coils, what you can do is purchase an in-line spark tester. You will find these at any auto parts store and they are not expensive. Place the tester on the spark plug and reconnect the wire to the tester and watch the light as it flashes. Should you see any gaps in the time that the coil fires then you have a bad coil and this will need to be replaced. DO NOT try to connect this tester with the engine running. It is rare, but the fuel pump will cause this condition as well. This will be from a weak pump or a clogged fuel filter. What to do here is, If you have one, connect a fuel pressure tester to the schrader valve on the fuel rail and watch for any discrepancies in the pressure as the engine runs. If there is, then I would start with the filter because the pump is in the tank and this will have to removed from the vehicle to replace it. Good luck with this.

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  • Master 3,076 Answers
  • Posted on May 16, 2011
Tim Whalen
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I would change the spark plug first as it is lease expensive, if that improves but is still running rough then I would change the coils, you might want to check the sensor,also. Hope this helped Tim

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2answers

All of a sudden started running rough ,showing code p0300 on 2005 buick lesabre custom 3.8l

"Basically this P0300 code 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."

https://www.obd-codes.com/p0300
0helpful
1answer

Starts up but runs rough, exhaust smells, and when you give it gas it wants to shut off.

How To Fix P0300 random misfire codes in your car ...

? 2:56
https://www.youtube.com/watch?v=OyvdWeyDHf4
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 - OBD-II Trouble Code - RepairPal

repairpal.com > Encyclopedia > OBD II Codes
OBD II Fault Code. OBD II P0300. Fault Code Definition. Random, Multiple MisfireDetected. Symptoms. Check Engine Light flashing; Rough running, hesitation ...

P0300 - Check Engine Light Diagnostic Trouble Code ...

https://www.engine-light-help.com/P0300-check-engine-light.html
The misfire detection monitor, a software strategy built into the computer, is designed to detect an engine misfire. The computer can also normally identify the ...

Random-Misfire Page

www.random-misfire.com/

0helpful
1answer

What is code p0300?

P0300 - Random, Multiple Cylinder Misfire Detected Fault Code Definition
  • Random, Multiple Misfire Detected
Symptoms
  • Check Engine Light flashing
  • Rough running, hesitation, and/or jerking when accelerating
  • In some cases, there may be performance problems, such as dying at stop signs or rough idling, hesitation, misfires or lack of power (especially during acceleration), and a decrease in fuel economy
Common Problems That Trigger theP0300
  • Worn out spark plugs, ignition wires, coil(s), distributor cap and rotor (when applicable)
  • Incorrect ignition timing
  • Vacuum leak(s)
  • Low or weak fuel pressure
  • Improperly functioning EGR system
  • Defective Mass Air Flow Sensor
  • Defective Crankshaft and/or Camshaft Sensor
  • Defective Throttle Position Sensor
  • Mechanical engine problems (i.e.-low compression, leaking head gasket(s), or valve problems
0helpful
1answer

Causes of p0300, p0302, p0304, p0306 in 2000 toyota avalon

P0300 = Random/multiple cylinder(s) - misfire detected.
P0302 = Cylinder 2 - misfire detected.
P0304 = Cylinder 4 - misfire detected.
P0306 = Cylinder 6 - misfire detected.

A misfire can be caused by a few things. The most common causes are usually spark supply or fuel supply. Get BOTH of these checked.
All the misfires are on the same side of the engine so I would suspect a fuel rail or an injector issue on that side of the engine.
3helpful
1answer

When my car is ran on computer is has cose PO300 PD. What does this indicate?

DTC P0300 - Random/Multiple Cylinder Misfire Detected
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.

Hope this helps.
1helpful
1answer

Code reads "random/multiple cylinder misfire

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 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 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.

Hope helps.
0helpful
1answer

Stalling and running rough

P0300 is Random/Multiple cylinder misfire detected. Give it a good tune up and that should take care of your problems.
0helpful
1answer

Engine light comes on - Code shows P0300 and then

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.

Possible Causes:

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
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