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  1. #1
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    braydon
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    98 4.6 slight shake at idle

    My 98 4.6 has a slight shake at idle, but when you are driving it runs fine. I have had a big misfire issue in the past and this is why I am worrying about it so much.

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  2. #2
    Member Moosee1955's Avatar
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    stevelandau
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    Slight shake is usually an intake leak somewhere along the way. Easiest way to find the leak is to use a smoke machine hooked up to the large hose from your power brake booster. You can build one, buy one for about $150.00, or pay a reasonable shop to do the smoking part. 2nd is use a propane small tank with hose and nozzle, and go around all intake points, throttle body, intake manifold, etc, 3 rd way is a can of $2.99 carb clean, and spray around all intake points. 3 rd way takes longest. Before all this run a Dtc codes check to see if anything is amiss. Oreillys or Autozones can do that part You might have one cylinder that's acting up just a little. New plugs or air filter might also be in order if it's been awhile.

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  3. #3
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    Alright, I know it's not the plugs because I just replaced them with motor craft ones. I can use my bluedriver scanner, and see if I can find anything out.

    Just trying to survive

  4. #4
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    I finally got around to replacing the fuel filter, and the truck runs like a top. Finally.

    Just trying to survive

  5. #5
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    Never mind, the fix only lasted a little bit. Back to shaking again sadly.

    Just trying to survive

  6. #6
    Member Moosee1955's Avatar
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    stevelandau
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    I could have told you that wouldn't stop shaking. Best bet, if I didn't already post is to smoke the intake system through hose that connects to brake booster. You can make your own, buy one, or pay a shop. You'll be amazed how many spots your 4.6 can leak from.

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  7. #7
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    braydon
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    So is this smoke tester for an intake or a vacuum leak? Or are they both essentially the same? I've searched up a smoke tester and all that is coming up is how to find a vacuum leak

    Just trying to survive

  8. #8
    Member Moosee1955's Avatar
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    Same thing. A vacuum leak is any component or gasket, or hose in the intake, or exaust system. It's wild to see smoke coming out an exaust manifold, or egr valve. Sometimes you'll see smoke coming from hoses, like the ones coming off pcv valve. You can also do it with carb spray, at each fitting, item, with motor running, it just takes a lot longer. Read up on that way as well, cheaper.

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  9. #9
    Junior Member
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    I probably dont have enough money at the moment for the smoke test, but I'll read up on how to do it with the carb cleaner.

    Just trying to survive

  10. #10
    Member Moosee1955's Avatar
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    stevelandau
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    You can make your own smoker fairly cheap. But yeah, carb clean sprayed around hoses/ gaskets, or use a propane small tank with a hose and nozzle does same. Obviously don't light propane, just the gas itself with motor running. I did that for years or the spray. Smoking is quickest, because the minute you apply smoke, motor off, it comes out anywhere that's leaking intake/exaust.

    Sent from my N9131 using Tapatalk

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