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95 Chev Suburban "service engine light"

Discussion in 'Chevy Suburban Forum (GMC Yukon XL)' started by slidercoach, Feb 10, 2007.

  1. slidercoach

    slidercoach New Member

    Hello, I have a 1995 K1500 Suburban with 5.7l engine with throttle body injection with 181,000 miles. It runs great except for the following condition:

    I drive to and from work each day about 25 miles one way. I reach highway speeds and I believe the engine gets thoroughly heat soaked. After about 15 miles, the "Service engine soon" light comes on every day. I believe the computer is OBD1, it has the 12 pin connector. I followed a procedure I found that says to ground pins A and B in the connector and turn the key on to retrieve codes. It did not flash, meaning to me the computer hasn't saved any codes, or this grounding in the connector doesn't work or some other problem with communication with the computer. Would anyone have suggestions?

    One side note about the engine. While the engine is still warming up and has not reached operating temp, the engine has a significant pre ignition knock when you put the engine under load. It reduces as the engine reaches operating temp.

    Any suggestions from anyone would be appreciated. Great website!
  2. slidercoach

    slidercoach New Member

    Update, I went to O Reillys to pick up a fuel filter and asked if they had a scan tool. They did and let me borrow it. I ran diagnostics on it and it had a code saved. 32 EGR FAILURE. That is the only code. If I did it correctly. So I went and inspected the vac line to the EGR valve, it looks ok. I reached in to the valve to see if it would move and it does. It doesn't appear to be stuck. I am going to remove it and inspect it and see if I can see anything.

    Any thoughts?
  3. unplugged

    unplugged Epic Member 5+ Years 1000 Posts

    Simple test

    To test an egr valve, I use a length of vacuum hose and apply suction to see if the egr valve operates and holds vacuum. If it doesn't, hold vacuum replace the valve.

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