I have also been told that I have multiple misfires.I have replaced the spark plugs and wires.I have also replaced the fuel filter and the fuel pressure sensor. I also replaced the intake manifold gaskets.
Hello,
Your question lists codes p305p, and p305, which are not valid codes. Did you mean P0305? This is a diagnostic code referring to a misfire on cylinder #5. It looks like you've replaced parts that could be causing a misfire, but did not fix the problem.
A simple check to verify your misfire is not being caused by an ignition coil (the 4.8 liter engine has a coil-near-plug system, with one coil for each spark plug) is to swap the suspect coil (cylinder #5) with a coil from a different cylinder on your engine.
Cylinder #5 is the third one back from the front of the engine on the driver side of the engine. After you swap coils between a good cylinder and #5 cylinder, clear the codes and see if the misfire followed the coil- if a misfire code sets on the cylinder you moved the cylinder #5 coil to, you know the coil has a problem. That will at least help you rule out the remainder of the ignition system.
SOURCE: service engine soon light on 2002 chevrolet tahoe stays on
That normally means that you have a issue with your gas cap try replacing your gas cap first then diconnect the negative terminal of the battery for about three minutes to clear the memory and start the truck again
SOURCE: po300 code possible fixes?
HI there:
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
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 this helps; also keep in mind that your feedback is important and I`ll appreciate your time and consideration if you leave some testimonial comment about this answer.
Thank you for using FixYa, have a nice day.
Testimonial: "thank you for your suggestions.codes were cleared,so far po140 has not returned (bank one,sensor two).code po300 returned in less than five minutes.will check vacuum,hoses,and egr next."
SOURCE: 2002 Chevy Silverado po300 po449 codes
Trouble Code: P0300 Multiple Cylinder Misfire Detected Possible Causes: EVAP Vent Solenoid Control Circuit Malfunction Possible Causes:
Base engine mechanical fault that affects one or more cylindersFuel delivery component fault that affects more than 1 cylinderEVAP system problem or the EVAP canister is fuel saturatedEGR valve is stuck open or PCV system has a vacuum leakIgnition system fault (a coil) that affects more than one cylinderTSB 03-06-04-030 contains a repair procedure for this codeTSB 03-06-04-041 contains a repair procedure for this codeTrouble Code: P0449
Vent solenoid control circuit is open or shorted to groundVent solenoid control circuit is shorted to system power (B+)Vent solenoid power circuit is open (test the ENG1 fuse)Vent solenoid is damaged or has failedPCM has failed
I don't think you really understand what this fault code means, it means that likely all the engine cylinders are misfiring at random no set pattern, not any particular cylinder. I would start with checking for engine vacuum leaks like the intake manifold gasket. that is all I can say since you provided no make, model or year and engine type and size information.
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