can a EGR valve cause a slightly rough idle on a 89 Mercury Grand Marque?

  • Thread starter Thread starter ddd
  • Start date Start date
most likely the iac which is the idle air control valve...the egr might be it also...but id check the iac and change that first..
 
yes it will and a bad egr valve will cause a real rough idle and cause it to miss-fire when you accelerate it also,and it will throw multiple miss fire codes on the computer when you scan it also,good luck.
 
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