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EGR Valve Issues

5/17/2010

 EGR Valve Issues

Purpose
  
The purpose of exhaust gas recirculation (EGR) is to reduce nitrogen oxide (NOx) emissions by returning a portion of the engine?s exhaust gas back to the engine?s combustion cylinders.  This reduces the amount of heat in the cylinder.  NOx formation progresses much faster at high temperatures, thus the EGR reduces the amount of NOx the combustion generates.  The EGR valve controls the amount of exhaust gases returned to the cylinders.  
 
Symptoms
 
   An improperly working EGR valve can cause hard starting, rough idle, lean misfire, exhaust smoking, and engine hesitation and stalling after cold starting.

   Disassembled visual inspection can show coking. 

      Varnish - fuel residue that could be a cold weather issue

      Sludge - in the form of oil and sooty carbon deposits and build up

Issues

   Replacing an EGR valve can cost from $300 to $1000 for parts and labor.

   Improperly cleaning an EGR valve can magnify problems.

   Bypass kits are available and easily installed for about $300 but defeat the purpose of reducing noxious, environmentally damaging emissions.

   Cleaning, replacing or eliminating the EGR valve does not deal with the root cause of the valves failure.

Causes 
 
 EGR valve deposits are generally un-combusted or incompletely combusted hydrocarbons from the diesel fuel.  Unburned hydrocarbons can come from low or mid-grade diesel fuel.  Longer ignition delay from lower quality fuel results in inefficient combustion and poor burning of the diesel fuel.

 Bio diesel is touted for it?s lubricity properties but, depending on the source of bio and production quality, it can contribute to unburned deposits.  (See Bio Diesel issues article.)
 
Solutions

   Ford Motor Company, in a Technical Service Bulletin for its dealers, recommends diesel fuel additives in the form of cetane booster and performance improvers along with good clean fuel to deal with the cause of coking issues.
   
   In a Topix.com forum, jdcaples from Seattle, WA explains it best.  He buys the best fuel he can, he blends the fuel to B-4 with soy-based biodiesel, and adds Amalgamated?s TDR-S to boost the cetane rating.    
   http://www.topix.com/forum/autos/dodge-sprinter/TMB5MO2TD12KNG01P#c10

   Amalgamated?s TDR-S and TDR-WDA are specially formulated with cetane improver to give 6+ Cetane Numbers.  This amount of cetane reduces the engine delay time by improving the combustion properties of all diesel fuels including low and poor quality fuels.  Improved combustion reduces carbon emissions and resulting EGR value deposits along with increased engine performance and improved mileage.

   TDR products also give the added benefit of detergency to clean an engine?s fuel system and keep the fuel injector system clean and free of deposit build-up.  Lubricity is also added to prevent fuel system wear.  Stabilizers are added to delay the natural degradation of the fuel and protect the fuel system from deposits and their harmful effects.
 
 
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