RPM bouncing at idle and IN GEAR, but goes away if top hole is plugged inside the TB?

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Aug 3, 2009 | 10:43 PM

aleks77

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From: Vancouver BC and Blaine WA, Ca/USA

RPM bouncing at idle and IN GEAR, but goes away if top hole is plugged inside the TB?

I just changed the headgasket, timing is dead on, everything is good that way. But the RPMs are bouncing like crazy, i set the dizzy at the same spot it was before i took everything apart and the rpm bouncing was like 1200 to 3200. Now i turned it all the way towards the front of the car and its holding at 1600 rpm. Seems like a bandaid not the fix. The IDLE screw on the TB is also tightened all the way in

Now if i take the intake piping off and close the TOP hole on the left inside the throttle body, the idle is perfect. Is this the IACV? If i close both holes car dies. So pretty sure there is no vacuum leak. Now i tried blocking off both the IACV and the FICV but no changes....

Also the car does not drive very well, kinda hesitates, feels like its lacking power...

Aug 4, 2009 | 06:33 PM

aleks77

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Joined: May 2005

Posts: 812

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From: Vancouver BC and Blaine WA, Ca/USA

Re: RPM bouncing at idle and IN GEAR, but goes away if top hole is plugged inside the

IACV and FICV replaced, problem still happening.

Does anyone know where else does the TOP LEFT hole inside the throttle body lead to besides the IACV?

Aug 4, 2009 | 10:16 PM

delsolproblems

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From: Portland, OR

Re: RPM bouncing at idle and IN GEAR, but goes away if top hole is plugged inside the

2 or 3 wire IACV? If 3, did you check the resistance of the IACV wires? Have you adjusted the TPS at all?

Aug 4, 2009 | 11:54 PM

aleks77

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Joined: May 2005

Posts: 812

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From: Vancouver BC and Blaine WA, Ca/USA

Re: RPM bouncing at idle and IN GEAR, but goes away if top hole is plugged inside the

alright guys, figured it out, i had a spare intake manifold laying around, so i took it apart, and blew compressed air into the top hole inside the throttle body, the air came out of the FITV so i blocked that hole, and the air came out of the #9 in the pic below, VALVE ASSY., AIR BOOST. So i blocked it off on my car, and voila, car runs perfect

I think i must have busted the valve inside this valve when i blew it out with compressed air (because it had some metal shavings in it). So for future reference:

Top Hole = FITV + Air boost
Bottom hole = IACV