Throttle body high/hanging idle

333arod333

SVT Disciple
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Oct 10, 2011
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801
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South Florida
Been reading on this all day.... I put in a new dragon throttle body yesterday and of course the idle is very high at around 1100 and hangs at 2000 rpm when taking it out of gear.

Here's what I did to try to fix it:
-warm car up
-unplug negative from battery and drain power
-unplug IAC
-start car and use set screw on tb to lower rpm to lowest i could: about 900 rpm
-unplug neg and drain power
-reinstall tune to get rid of previously learned idle memory
-plug in iac

start car and it will stay at 1100 with the iac plugged in, and if I drive around even at 1500 rpm, as soon i take it out of gear, it jumps to 2000 rpm before slowly winding down.

My tps is reading .98 and jumps to 1.04 and keeps switching back and forth rapidly. Is the problem that I haven't slotted my tps and moved it to stay at .98? Is it that important for it to be at only .98? I have also heard .90 in some threads...

Any thoughts? How can I lower that damn idle? Should I put a bigger return spring on the tb so the rpms don't hang? Or is that like a bandaid and not actually solving the real problem?
 

Blueline

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Jan 27, 2011
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4,923
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New Jersey
You may need a tune to get it worked out. But also check to see if there is a black ring around the inside of the throttle body which helps the blade seal. Stefan at dragon has been adding this sealer to help with this. Some of the older tbs won't have it and if you have an older one, you can send it in to him. If it's a newer one with the sealer and acting like this, may just need a tune revision.
 

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