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adjusting secondary butterflies

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Old 09-21-10, 10:29 PM
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adjusting secondary butterflies

Hey guys,

Just trying to set my idle and it seems its proving difficult, as I cant get it to idle nicely anything under 900rpm on the power fc (in actual fact it idles 1000 or 1100)

AAS screw is completely in, less than half turn out.

TPS is adjusted correctly. yet as soon as I take down the fuel f/c settings below 1000, it will hunt idle, If I keep the fuel fc settings above 1000 it idles alright, and no mattter what I do with the other idle settings it will not fluctuate or lower.

so my guess is that the power fc settings cant keep up with too much air coming in, so my only guess is that the secondaries are open too much. when I was cleaning out the TB, i did find the secondaries were slightly more of an angle than the primaries.

is it a good idea for me to fiddle with this ?
Old 09-21-10, 10:49 PM
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There is an idle adjustment screw on the front of the TB, use a small screwdriver to loosen the screw a bit to lower your idle. There's an 8mm nut that locks the screw into place, loosen that first.
Old 09-21-10, 11:05 PM
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I think Im actually missing this screw, you are talking about the primary throttle adjustment ?
I'll have a look again but there is a screw missing from this, which woulud mean its completely shut all the time ? or am I mistaken
Old 09-21-10, 11:52 PM
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The adjustment you have mentioned is the adjustment of the secondary valves isnt it ? it adjust how closed it is ? (if that makes sense)
Old 09-22-10, 12:09 AM
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Are you sure it isn't too lean? Lean mixture causes misfire and surging.
Old 09-22-10, 03:18 AM
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Im sure its running quite rich, its more or less hunting than misfiring its a very stedy bounce up and down. and it does it as soon as I change that f/c value under 1000.

My guess was that the power fc cant compensate for the setting because there is too much air coming in and is out of its range ? or am I talking non sense
Old 09-22-10, 07:57 AM
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Datalogit logs would help a lot
Old 09-22-10, 07:57 AM
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Originally Posted by GoodfellaFD3S
There is an idle adjustment screw on the front of the TB, use a small screwdriver to loosen the screw a bit to lower your idle. There's an 8mm nut that locks the screw into place, loosen that first.
Here is the screw Rich was talking about. Also check to see your throttle cable is not too tight.
Attached Thumbnails adjusting secondary butterflies-throttle-screw.jpg  
Old 09-22-10, 09:44 AM
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If you're missing that screw, then you can't lower the idle any more via that means.

Have you checked for vacuum leaks under and around the UIM? Spray brake/carb cleaner around culprit areas and see if the idle drops.
Old 09-22-10, 02:22 PM
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checked for leaks, but couldnt find any. I am missing that screw, but I would have thought with it missing, it would shut fully and cant be adjusted to open it, so thought it was a none issue with what Ima having ?
cable is some what tight, but I dont believe this is contributing to the high idle, there is definately slack there.
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