How Can I Tell if My EGR Valve Needs to be Cleaned or Replaced? The Exhaust Gas
Recirculation (EGR) valve is an important part of the exhaust circulation system
of a vehicle. EGR valves have been in use in the United States since the
1960s,when car companies were seeking ways to increase the efficiency of
vehicles while also decreasing pollution. When the EGR valve is clogged or
malfunctioning,it can cause irregularities in engine performance such as rough
idling or valve knock,indicating that the EGR valve should be inspected. The EGR
valve works by routing a small amount of exhaust back into the combustion
chamber. When the temperature in the combustion chamber is too high,nitrogen
oxides are produced,which combine with elements in the atmosphere to form smog.
Introducing a small amount of exhaust into the system reduces the temperature in
the combustion chamber,reducing the amount of nitrogen oxides produced. Many EGR
valves are mechanical,and simply have a small valve which opens to allow exhaust
into the combustion chamber and closes when it is not necessary,and to keep the
air mixture optimal for combustion. Some mechanical versions will not open until
there is sufficient back pressure,ensuring that the valve will not be open when
the engine is idle or warming up and needs a higher concentration of oxygen for
combustion. Electronic EGR valves are also available,and use electronics to
regulate the valve. If the EGR valve is stuck open,it will essentially cause a
vacuum leak,leading to inefficient combustion,rough idling,hesitation,and
sometimes stalling in extreme cases. This is because the car cannot combust on
carbon dioxide from the tailpipe - it needs atmospheric oxygen. If the
combustion chamber is flooded with exhaust from an open EGR valve,it will not
function properly. To check and see if the EGR valve is stuck open,have someone
idle a parked vehicle with the brake on while you examine the plunger shaft to
see if it is stuck open autel
ms908p. If the EGR valve is stuck closed,emissions of nitrogen oxides will
rise,and the car may start to knock. Spark knock happens when the fuel mixture
in the combustion chamber ignites before it has been reached by the explosion in
the cylinder,resulting in a disruption of the engine timing Autolink
AL539 Scanner. In this instance,the engine should be warmed up and revved to
see if the EGR valve will move. In both cases,simple repairs are possible. The
EGR valve can be clogged,and a simple cleaning of a mechanical EGR valve may
solve the problem. In the case of an electrically controlled EGR valve or a more
complex mechanical problem,replacement of the valve may be needed. The EGR valve
is an expensive motor vehicle component,and care should be taken to ensure that
it needs to be replaced rather than repaired. A reputable mechanic should advise
you appropriately. Failure to repair or replace the EGR valve will not lead to a
life threatening condition,although it will reduce the life of your car and
increase the potential emissions. Especially in areas which require smog
testing,an automobile with a malfunctioning EGR valve may not pass.
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