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  1. #1
    thompsdw's Avatar
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    Idle Speed Fluctuations

    What are the main causes of idle speed fluctuations in a 4Tec engine? For simplicity sake, lets eliminate the supercharger from this discussion and focus on the engine naturally aspirated. I am looking for the common causes of loping in the base model engine and how to resolve those issues.


  2. #2
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    Quote Originally Posted by thompsdw View Post
    What are the main causes of idle speed fluctuations in a 4Tec engine? For simplicity sake, lets eliminate the supercharger from this discussion and focus on the engine naturally aspirated. I am looking for the common causes of loping in the base model engine and how to resolve those issues.

    A leak AFTER the TB, or TPS sensor...

    How much variance are you seeing?

  3. #3
    King_Of_Fun's Avatar
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    My GTX SC moves from 1700-1840 rpms idling in the water. Are you seeing more?... Ron

  4. #4
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    Air leak is number one cause of idle fluctuations as described.

  5. #5
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    How much can it fluctuate and still be acceptable?

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    thompsdw's Avatar
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    That is what I thought. Are there any specific issues that normally occur in the TB? I am probably seeing more like a 200 rpm swing. It is not consistent all the time. Sometimes it seems to surge a little more than others.

  7. #7

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    I.a.c. Motor sticking? Or tps out of range.todd

  8. #8
    Avion3333's Avatar
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    i saw this problem before where the ski would drop to about 1000 rpm from 1840rpm we changed the spark plugs and the coils n we were good to go this was on a naturally aspirated 4tec engine i dont think this would be the main cause because it sounds like your ski is super charged so i'm not really sure maybe 1 of the gurus will chime in

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