engine shake - 91 el dorado 4.9
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HT4100 4.1, 4.5, 4.9 Discussion, engine shake - 91 el dorado 4.9 in Cadillac Engine Technical Discussion; hello everyone let me first say i'm lovin the forum i have a 91 el dorado. it was having missfires ...
  1. #1
    oaklandish is offline Cadillac Owners Member
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    Question engine shake - 91 el dorado 4.9

    hello everyone let me first say i'm lovin the forum

    i have a 91 el dorado. it was having missfires and a high idle. i replaced the fuel injectors and the car idles fine and doesnt miss. but now upon acceleration i feel the engine shake a little bit. it was 10x worse before the new injectors but it still occurs none the less. does anyone have any ideas what could be causing this? i dont think its related to the injectors even though it seemed to lessen the problem when i replaced them.
    the car passed smog today so emissions are running fine. new stuff:
    egr valve and solenoid
    cat converter
    all 8 fuel injectors
    spark plugs, wires, and distributor + rotor
    o2 sensors
    oil and filter

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    drewsdeville is offline Cadillac Owners Master
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    Re: engine shake - 91 el dorado 4.9

    I have to ask, you never mentioned, did you check for codes?

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    oaklandish is offline Cadillac Owners Member
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    Re: engine shake - 91 el dorado 4.9

    yes sorry, before i installed the new parts i had a code for egr system failure. now i have no ecm codes. i also forgot to mention, when i rev the gas it doesnt die down as fast as it did before

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    drewsdeville is offline Cadillac Owners Master
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    Re: engine shake - 91 el dorado 4.9

    You could be looking at a vacuum leak somewhere. Have you checked for any?

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    Ranger is offline Cadillac Owners Member
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    Re: engine shake - 91 el dorado 4.9

    Have you cleaned the TB and roded out the EGR tubes inside of it?

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    jamesmdx1 is offline Cadillac Owners Fanatic
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    Re: engine shake - 91 el dorado 4.9

    you should disconnect battery to reset computer to idle re-learn after all the cleaning of the TB is done

  8. #7
    oaklandish is offline Cadillac Owners Member
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    Re: engine shake - 91 el dorado 4.9

    Quote Originally Posted by jamesmdx1 View Post
    you should disconnect battery to reset computer to idle re-learn after all the cleaning of the TB is done
    yes i cleaned the throttle body but what is roded out the egr tubes?
    the battery was disconnected yesterday to hook up an amp kit

  9. #8
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    Sevillian273 is offline Cadillac Owners Connoisseur
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    Re: engine shake - 91 el dorado 4.9

    Alot of instances where there are no codes, it is a fuel problem. You might want to check the fuel pressure with a test kit. Harbor Freight has them for $20. Also, with the key on and engine off, pull the vacuum hose off of the fuel pressure regulator and look for any signs of fuel inside. There should be none.

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