What would cause 1996 Ford Explorer to overheat then idle high and low?
Only a few general
concepts, keep in mind that the exhaust gas recirculation (EGR) valve
is an integral part of a vehicles emissions control systems. It operates
under the premise of lowering combustion chamber temperatures to reduce
the amount of pollutants created by the combustion process. Being
closely tied to the combustion process, this valve's operation has
direct effect on the overall performance of the engine. Poor or faulty
operation of the EGR valve can result in several notable symptoms and
leads to increased pollutant emissions.
Poor Idle: An improperly closing EGR valve will act as a vacuum leak,
disrupting the correct fuel and air mixture, causing a lean mixture
condition. This results in misfiring cylinders and poor engine idle.
Overheating: The basic function of the EGR valve is to introduce exhaust
gases into the combustion chamber at specific and controlled rates,
lowering combustion temperatures, and lowering pollutant emissions. An
EGR valve that does not open properly fails to introduce sufficient
amounts of exhaust gases, causing combustion chamber temperatures to
rise, leading to overheating of the engine.
Poor Fuel Economy: A sticking EGR valve will not open and close at the
proper rate, leading to a reduction in the efficiency of the combustion
process due to the lean fuel-air mixture it causes. This results in the
engine having to work harder to perform the same amount of work,
requiring more fuel to do it. On-board computer systems can also try to
compensate for this lean condition by introducing additional fuel to the
mixture, further increasing fuel consumption.
Increased Emissions: EGR valves are designed to lower the emission of
pollutants from the combustion process. This is done by lowering the
temperature of the combustion process through the introduction of
exhaust gases into the fuel and air mixture. Lowered combustion
temperatures result in more efficient burning of the fuel and air
mixture, and less pollutants in the exhaust emissions. An improperly
operating EGR valve will not correctly lower combustion temperatures,
causing noxious emissions to increase, which can cause a vehicle to fail
Test cylinders compression and check if some fault code is stored in the PCM 9computer).
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Oct 15, 2011 |
1996 Ford Explorer