Question about 2002 Chevrolet Silverado 1500
Replaced spark plugs, spark plug wires. Checked coils. Checked injectors. Replaced fuel pump, fuel pressure regulator, intake gasket, battery, fuel filter, maf sensor, map sensor, and timing chain. Vacuum still around 15, haven't checked fuel pressure again should b good. If there is a vacuum leak i cant find it spraying carb cleaner. I dont know what else to do. Any ideas?
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
Multiple Cylinder Misfire Detected
EVAP Vent Solenoid Control Circuit Malfunction
Posted on Dec 12, 2012
Have you checked the EGR valve? The P0449 EVAP code is normally or the purge solenoid on the intake. Unplug the line that feeds the EVAP system from the purge valve and connect a vacuum gage. It should flutter while it is activated. If not, that could be the culprit.
Posted on Dec 12, 2012
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Posted on Jan 02, 2017
SOURCE: po300 code possible fixes?
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
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.
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Posted on Aug 03, 2012
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."
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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.
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