Remove the HT cable from cylinder 3 with engine running spark should jump 1/4 inch to block of engine, if so cable and coil ok .remove spark plug and compression test , if plug and compression ok refit plug, start engine and back probe injector with led test light, if injector pulse ok clean or replace injector..
Hello
Here is what to check let me know if you need help checking this out
most common misfire causes on the cars I've worked on have been:
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.,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
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
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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.
check fuel injector pressure regulator
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It can be issue with spark plugs or faulty spark plugs. Also
get the compression test done for cylinders. If any of cylinder shows low
compression then required, then that particular cylinder will cause misfire.
Also get obd codes scanned, the error code will let you know
which cylinder is misfiring or all cylinders are misfiring.
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For your trouble shooting I suggest you to refer the help
oinks below. It has step by step details for many engine misfire issues.
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Click the link below:-----
Ford Explorer Cylinder Misfire?
http://whoisbyme.blogspot.in/2012/06/ford-explorer-cylinder-misfire.html
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Engine Misfire codes on Chevrolet Malibu?
http://schematicsdiagram.blogspot.com/2011/12/engine-misfire-codes-on-chevrolet.html
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Cylinder 6 Misfire?
http://howtobyme.blogspot.com/2011/12/cylinder-6-misfire.html
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Misfire on cylinder 4?
http://schematicsdiagram.blogspot.com/2011/12/misfire-on-cylinder-4.html
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While stop engine idles like cylinder missing?
http://schematicsdiagram.blogspot.com/2012/01/while-stop-engine-idles-like-cylinder.html
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Ford Explorer 5.0L: Engine Miss?
http://whoisbyme.blogspot.in/2012/06/ford-explorer-50l-engine-miss.html
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Oil on spark plugs and car misfires?
http://technoanswers.blogspot.in/2012/02/oil-on-spark-plugs-and-car-misfires.html
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Can cylinder misfire Damage the Catalytic converter?
http://schematicsdiagram.blogspot.in/2012/02/can-cylinder-misfire-damage-catalytic.html
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Car misfires and error code P0306 and P0303 is shown?
http://technoanswers.blogspot.com/2012/01/car-misfires-and-error-code-p0306-and.html
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Chevrolet K1500 No spark, random misfire
http://repairhelpcenter.blogspot.com/2012/11/chevrolet-k1500-no-sparkrandom-misfire.html
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2004 Ford F150: Engine Misfire and Lean Code?
http://whatisbyme.blogspot.in/2012/05/2004-ford-f150-engine-misfire-and-lean.html
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1995 Toyota LS: Misfire at idle or low RPM
http://whatisbyme.blogspot.in/2012/04/1995-toyota-ls-misfire-at-idle-or-low.html
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Toyota Corolla:
Random Misfire?
http://technoanswers.blogspot.in/2012/04/toyota-corolla-random-misfire.html
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2006 Ford Freestar: Misfire on Cylinder Number 2?
http://whatisbyme.blogspot.in/2012/06/2006-ford-freestar-misfire-on-cylinder.html
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This will help.
Thanks.
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