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  1. #1
    Pwgsx's Avatar
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    TPS - Idle issue and rpm loss

    I reset both of my engine tps's on my boat bc one doesn't idle right, sometimes it drops below 2,000rps before picking back up when I give it a throttle rev, sometimes it just dies. This one engine is also 500rpms lower than the other when running WOT or even at 5,000. I first checked with the CanDoo and found 0 and 86 / 0- 81- on the troubled engine. After the reset I got 86.8 and 79. I tried to adjust the throttle cable on the one reading 79 thinking there was too much slack. I adjusted it until I saw the butterfly move and then backed it off a tad. I reset it again and got 80.7. Even if I move the butterfly by hand I can only get 81 so I know its not something with the throttle having too much slack. Any ideas? It has new plugs, new gas- the other engine rev's fine and tops out right at 8,000 vs 7,500 on the other.


  2. #2
    Pwgsx's Avatar
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    Anyone

  3. #3
    Moderator beerdart's Avatar
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    Its expressed in degrees of blade angle so 81 ish is normal as at idle the blade is set aprox 7-9 deg. So 9+81=90 deg.

  4. #4
    Pwgsx's Avatar
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    So would the one reading 86 be too much? I cant seem to find out why one engine idles bad and is lower on rpms than the other. This is on a Speedster 200 btw.

  5. #5
    Moderator beerdart's Avatar
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    No the TBs are calibrated at the factory for idle blade angle your idle problem is not the blade angle.
    Quote Originally Posted by Pwgsx View Post
    So would the one reading 86 be too much? I cant seem to find out why one engine idles bad and is lower on rpms than the other. This is on a Speedster 200 btw.

  6. #6
    Pwgsx's Avatar
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    If its not that then where should I be looking now? Idle valve issue.... How do I check that? It seems like it only does it when the engine is cold, if I gas it, it drops and picks back up if I feather the throttle, if not it will die. Once I can get it to rev it seems fine but seems a bit rough as the other engine is nice and smooth with moving the throttle. This same engine has a oil pressure switch fault- TOPS valve works, wiring is ok. I plan to change both sensors out this weekend. Could that cause a bad idle even if at the time it hasn't tripped a warning light?

  7. #7
    Moderator beerdart's Avatar
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    Fuel system spark plugs coils etc.

  8. #8
    Yeah, I would start with new plugs.

  9. #9
    Pwgsx's Avatar
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    It has new plugs, maybe 1 hr on them- that didn't fix the issue, I'll swap coils from the good running engine and see what they do.

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