1992 Cadillac Deville egr valve

1992 CADILLAC DEVILLE
4.9L • V8 • RWD • AUTOMATIC
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REARDRIVE
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When I first start the engine it run fine but as it warm up the motor start running different ,in a few minutes it start back running fine .can it be the EGR valve or the map sensor are going bad
May 12, 2014 at 8:27 AM
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JACOBANDNICKOLAS
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When it starts running bad, can you describe what it does? Also, has the check engine light come on? Last, have you checked things like fuel pump pressure, the catalytic converter to see if it is plugging, check for vacuum leaks...?
May 12, 2014 at 9:06 AM
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REARDRIVE
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when car start running bad it sound like it is serging up and down,no check engine is on and no the fuel pump and catalytic converter havent been check out
May 12, 2014 at 10:14 AM
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JACOBANDNICKOLAS
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Is the surging only at an idle?
May 12, 2014 at 10:36 AM
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REARDRIVE
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yes
May 12, 2014 at 12:47 PM
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JACOBANDNICKOLAS
  • ✓ASE Certified Mechanic
  • 110,194 POSTS
  • ASE Certified Mechanic
My first guess is either you have a vacuum leak or the idle air control valve (IAC) is going bad. The IAC is responsible for maintaining a smooth idle speed.
May 12, 2014 at 5:54 PM
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