Interesting 4.9 symptom, need ideas

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HT4100 4.1, 4.5, 4.9 Discussion, Interesting 4.9 symptom, need ideas in Cadillac Engine Technical Discussion; Hi all, I have a 1991 Fleetwood 4.9 with 167,003 miles on the clock. The car runs very well, but ...
  1. #1
    JK2402 is offline Cadillac Owners Member
    Automobile(s): 1991 Cadillac Fleetwood
    Join Date
    Nov 2005

    Interesting 4.9 symptom, need ideas

    Hi all, I have a 1991 Fleetwood 4.9 with 167,003 miles on the clock. The car runs very well, but it is doing one thing that bothers me. At idle, like when stopped at a light, the engine feels like it has a miss. Its not random, but rhythmical. Just had a full tune up done and has been doing this since I got the car, but it seems like it might be getting worse? The car runs great with this exception. Has anyone ever experienced this or have any ideas? Thanks, Justin

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  3. #2
    awadecki is offline Cadillac Owners Enthusiast
    Automobile(s): 76 Eldo (54k), 76 Eldo (52k), 78 Eldo (9k), 85 Deville (43k)
    Join Date
    Jun 2005

    Re: Interesting 4.9 symptom, need ideas

    Either a stuck EGR valve, plugged EGR tubes, or leaky fuel injector.

  4. #3
    caddydaddy's Avatar
    caddydaddy is offline Cadillac Owners Connoisseur
    Automobile(s): 2005 Escalade 6.0L 2WD, 2007 Jeep Grand Cherokee Limited CRD
    Join Date
    Jan 2003
    Gales Ferry, CT

    Re: Interesting 4.9 symptom, need ideas

    Mine will do a little shake at idle once in a while. I have all fresh tune up and EGR parts, so I just attribute it to having 141,000 miles on it. It's nothing major, but noticeable.

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