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  1. #1
    big john's Avatar
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    adjusting the base idle on a 1.8L motor

    does anyone have any idea if the cold and hot base idle is adjustable and how on the 1.8L NA motor, i'm figuring it has to done thogh the ECU, but just seeing if there is another method , radical cam timing changes causes poor idle, but let me tell ya, it sounds like a pro stock race ski !!!!


  2. #2
    My name is Sean and I am addicted to STXs smokeysevin's Avatar
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    Re: adjusting the base idle on a 1.8L motor

    I'm assuming it idles low, if that's the case you could drill a small hole in the butterfly.

    What exactly do you heed to do?

    Sean

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    big john's Avatar
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    Quote Originally Posted by smokeysevin View Post
    I'm assuming it idles low, if that's the case you could drill a small hole in the butterfly.

    What exactly do you heed to do?

    Sean
    it idles low and rough, changed the cam timing and it's not correcting its self, it sounds nasty to say the least !!!!!! and of course, its IAC controlled, needs to be stepped up to idle, as it is its idling low and dieing on the trailer, its going to be worse in the water.

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    My name is Sean and I am addicted to STXs smokeysevin's Avatar
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    Re: adjusting the base idle on a 1.8L motor

    Do you know what the control type is on the 1.8? The Kawi runs speed density up to 8% and above 12% its alpha n 8-12% it is a blend. On my project its a blend the same way. If its running speed density (rpm and map) its more difficult to adjust because cams kill the map readings. My ski idles at 65 kpa. If its alpha n (tp and rpm) its a little easier you can clock the tps slightly so it reads higher and that might smooth out the idle. Otherwise just crank open the throttle butterfly a bit or drill a small hole to up the idle to around 13-1500 rpms and that should help. The other thing you may want to try is bumping the fuel pressure up, my ski will idle at 14-16 AFR but its much better at 12.5-13.5.

    Sean

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    jetpilot785's Avatar
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    What is your vacuum at idle? Should be 13-15 in. Do you have a pic of the tower marks with piston 1 at TDC to see if it is over advanced? What cams did you install? I'm guessing your VXS?

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    big john's Avatar
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    Quote Originally Posted by jetpilot785 View Post
    What is your vacuum at idle? Should be 13-15 in. Do you have a pic of the tower marks with piston 1 at TDC to see if it is over advanced? What cams did you install? I'm guessing your VXS?
    just advanced the stock cams on my VXS, +7 intake, -2 exhaust, might have to go back to 0 on the exhaust since there is a CPS on the exhaust....

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    jetpilot785's Avatar
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    Quote Originally Posted by big john View Post
    Quote Originally Posted by jetpilot785 View Post
    What is your vacuum at idle? Should be 13-15 in. Do you have a pic of the tower marks with piston 1 at TDC to see if it is over advanced? What cams did you install? I'm guessing your VXS?
    just advanced the stock cams on my VXS, +7 intake, -2 exhaust, might have to go back to 0 on the exhaust since there is a CPS on the exhaust....
    Gotcha, i don't know off hand what is recommended for stock cam advancements on the N/A engine but if the ski idles that rough and will not correct itself, it may be too aggressive. I would try +5 intake and 0 exhaust and see if that cleans it up. Are you using adjustable cam gears? If you want feel free to post a pic of the timing marks with piston 1 @TDC just to give us an idea of where things are at. I know it is a pain in the ass to take the cover off and line it up again but it may help us study it better.

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    My name is Sean and I am addicted to STXs smokeysevin's Avatar
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    Re: adjusting the base idle on a 1.8L motor

    Depending on how the ecu finds tdc that might be the problem. On mine the cam sensor just resets the counter. What is the Yamaha crank wheel setup?

    Sean

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    big john's Avatar
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    [QUOTE=jetpilot785;2055580][QUOTE=big john;2055577]
    Quote Originally Posted by jetpilot785 View Post
    Gotcha, i don't know off hand what is recommended for stock cam advancements on the N/A engine but if the ski idles that rough and will not correct itself, it may be too aggressive. I would try +5 intake and 0 exhaust and see if that cleans it up. Are you using adjustable cam gears? If you want feel free to post a pic of the timing marks with piston 1 @TDC just to give us an idea of where things are at. I know it is a pain in the ass to take the cover off and line it up again but it may help us study it better.
    i had been running it at +5 int 0 exh for most of the summer, just want a little more. it seems the no one has really done any real work on the NA motor to see what works and what doesnt...... i guess i'm that guy????? the R&D gears are a pain to change any settings, so i went to riva gears, it just might be too much, i really need to water test it to see if its worth keeping this way and figuring out how to raise the idle

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    jetpilot785's Avatar
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    [QUOTE=big john;2055598][QUOTE=jetpilot785;2055580]
    Quote Originally Posted by big john View Post
    Quote Originally Posted by jetpilot785 View Post
    Gotcha, i don't know off hand what is recommended for stock cam advancements on the N/A engine but if the ski idles that rough and will not correct itself, it may be too aggressive. I would try +5 intake and 0 exhaust and see if that cleans it up. Are you using adjustable cam gears? If you want feel free to post a pic of the timing marks with piston 1 @TDC just to give us an idea of where things are at. I know it is a pain in the ass to take the cover off and line it up again but it may help us study it better.
    i had been running it at +5 int 0 exh for most of the summer, just want a little more. it seems the no one has really done any real work on the NA motor to see what works and what doesnt...... i guess i'm that guy????? the R&D gears are a pain to change any settings, so i went to riva gears, it just might be too much, i really need to water test it to see if its worth keeping this way and figuring out how to raise the idle
    Gotcha. If it were me I would reset the exhaust to 0 leaving the intake at 7 and try it again and if it still has the issue then go back to what you had. I don't know if I would tamper with the throttle plate to raise the idle. It is all computer controlled. I would reset the cams and go from there. I don't know enough about the TB if drilling holes or whatnot would have adverse affects leaving you with replacing it. If the computer won't compensate, then your settings are too far off. I don't know if modifying the plate would even raise idle as i would think the computer would find a way to correct it and if it can't, would the engine high idle all the time?

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