Originally, the P0300 misfire code was being thrown. I have replaced the EGR valve/sensor assembly. The car still throws a P0405 EGR code. It runs rough and hesitates when cold, but runs well when warm. Any advice?
P0300 Diagnostic Code - Random Misfire
Technical description:--
Random/Multiple Cylinder Misfire Detected:---
Exactly what does this code means:--
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:--
the engine may be harder to start.the
engine may stumble / stumble, and/or hesitate.
other symptoms may
also be present…There may be rough idle,
sputters and stalls and jerks.
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 for this error problem:--
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 vehicle, 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 un-metered air getting past the airflow sensor,
or an EGR valve that is stuck open.
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Did you clear the code after putting on egr!
I"ve got a 97 olds surpreme cutlass and replaced 3 avg values and the light is still on and every time I change egr I take it over and have the light turned off and it still comes on maybe a day or 2 months
SOURCE: Oldsmobile Alero EGR valve bad
yes you can do it yourself the egr valve is located on the exaust manifold closest to the fire wall unfortunately it has to be replace. it has an electronic lead to it and is vaccum operated to replace it is not a difficult task. the part can be purchased at a Napa or Oreilly's for alot less than at a dealership. just make sure your gasket surfaces are clean for replacement of new gaskets. if you have a code reader than can reset the code that is a benefit however if you do not you have to have a scan tool to reset the code. please rate the solution....thanks
SOURCE: 95 Ciera Hesitates & stalls when warm
Change the IAC the idle air control. You may be able to clean it and put it back on.
A code P0300 may mean that one or more of the following has happened:
If there are symptoms such as the engine is stumbling or hesitating, check all wiring and connectors that lead to the cylinders ( 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 (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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i have the same problem but we have changed the egr valve 2 times and it still throws a service engine code. finally we switched the housing on it with one from the junkyard which is a original and it worked for 3 days then threw a code, any help i need it.
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