WHAT ELSE CAN I CHECK ON MY 4.3 ENGINE THAT RUNS ROUGH AT LOW SPEED RUNS FINE AND FASTER SPEED

  • Tiny
  • Peasant
  • 1991 GMC Sonoma
  • 184,000 miles

1991 gmc sonoma sle 4.3 4x4 runs rough at low speed runs fine and faster speed, I've replaced plugs wires cap rotor, air filter set the timing, cleaned venture carbon with cleaner and tooth brush also replaced Idle Control Valve. I've checked all the vacuum hoses and did the throttle body gasket check thing with carburetor cleaner. Not sure what else to do. Can you help.
Thanks.
Ugo

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Friday, July 20th, 2012 AT 11:18 AM

3 Replies

  • Tiny
  • KHLow2008
  • Expert
  • 41,994 posts

If equipped with EGR, check the system.

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Friday, July 20th, 2012 AT 12:00 PM
  • Tiny
  • Peasant
  • Member

EGR system checks out ok.I'd like to add it runs rough when below operating temperature I've also replace the temperature sensor. Once it's up to operating temperature it idles and runs fine. What next.

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Sunday, July 29th, 2012 AT 11:59 AM
  • Tiny
  • KHLow2008
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  • 41,994 posts

Have the compression checked and valve clearances readjusted and retest.

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Sunday, July 29th, 2012 AT 2:24 PM

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