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Ported TB, now high idle.

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Old Feb 12, 2009 | 06:11 AM
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Default Ported TB, now high idle.

I ported my TB today, just used a dremel and ported it pretty big, also knife edged the blade and cut the shaft, and now its idling around 900-1100 stopped at a light and around 1800-1900rpm if I put in in D or N. When I start the car, it idles normally at 500rpm, but once I start moving I get these problems. The pedal also feels like the blade is getting a little stuck off idle... Any ideas?
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Old Feb 12, 2009 | 06:35 AM
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did you end up porting the area where the throttle blade closes? if you did, there may be too much air entering even though the blade is closed.
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Old Feb 12, 2009 | 06:45 AM
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Originally Posted by Grimes
did you end up porting the area where the throttle blade closes? if you did, there may be too much air entering even though the blade is closed.
yup sounds like you ported to close to the throttle blade, also i am guessing you took off too much material when you knive edged the butterfly...might wanna get a new blade...if that doesnt help, you will need a new throttle body...
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Old Feb 12, 2009 | 07:50 AM
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your TB is over-ported around the TB blade. thats what would be causing your problem
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Old Feb 12, 2009 | 09:37 AM
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When I was porting TB's for the masses I quit knife edging the blade because it was causing idling issues. There's no other way to fix it other than replacing the blade.

FYI, you're probably seeing 50% or less of the porting gains doing it with a dremel. There's no possible way you can properly blend, smooth, and remove the right amount of material with one. I've tried several times before and it's not possible, compared to using the correct tools. You might want to send yours off to be finished, and have the blade replaced at the same time.
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Old Feb 12, 2009 | 10:54 AM
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When I was porting TB's for the masses I quit knife edging the blade because it was causing idling issues. There's no other way to fix it other than replacing the blade.

FYI, you're probably seeing 50% or less of the porting gains doing it with a dremel. There's no possible way you can properly blend, smooth, and remove the right amount of material with one. I've tried several times before and it's not possible, compared to using the correct tools. You might want to send yours off to be finished, and have the blade replaced at the same time.
Now, I'm not trying to snake your technique or anything, I do some porting myself, but could you elaborate on what tools and technique you're using? PM me if you don't want to tell everyone on the board.
Thanks!
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Old Feb 12, 2009 | 11:18 AM
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Originally Posted by nemss1
your TB is over-ported around the TB blade. thats what would be causing your problem
X2, Sounds like you have cut to much around where the blade closes up
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Old Feb 12, 2009 | 12:03 PM
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Well I marked where the blade sits before I started porting and Im pretty sure I didnt hit that area... I drove it this morning and it seems like the blade wants to stick when in the closed position. For example ill start the car the idle will be normal but as soon as I tap the throttle it feels like I have to break the blade loose, and my idle problems begin from there. Is it possible the blade is not centered correctly?
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Old Feb 12, 2009 | 12:06 PM
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Originally Posted by TireSm0ke
Well I marked where the blade sits before I started porting and Im pretty sure I didnt hit that area... I drove it this morning and it seems like the blade wants to stick when in the closed position. For example ill start the car the idle will be normal but as soon as I tap the throttle it feels like I have to break the blade loose, and my idle problems begin from there. Is it possible the blade is not centered correctly?
Yea, I had the same problem, seems like it is definitely sticking, could be off-center like you said. Take it off and manually open and close it, you should be able to see pretty clearly where it's sticking
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Old Feb 12, 2009 | 12:08 PM
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Evan,

Sounds like the throttle blade is not centered or the blade is closing too much and binding on the housing. Center the blade on the housing by loosening the blade bolts and allowing the blade to sit freely while closed. Tighten the bolts in place. Then ensure the blade is not sticking as you crack it open, you will need to adjust the idel set screw to hold the blade just a hair open, just prior to sticking. If you need help, just bring it by.
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Old Feb 12, 2009 | 05:34 PM
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i didnt knife-edge my blade seeing that it is really easy to screw up and not seal all the way. i wouldnt recommend knife-edging the blade. will difinitely cause probs if screwed up and is very simple to screw up
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Old Feb 12, 2009 | 09:20 PM
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Originally Posted by 12secSS
Evan,

Sounds like the throttle blade is not centered or the blade is closing too much and binding on the housing. Center the blade on the housing by loosening the blade bolts and allowing the blade to sit freely while closed. Tighten the bolts in place. Then ensure the blade is not sticking as you crack it open, you will need to adjust the idel set screw to hold the blade just a hair open, just prior to sticking. If you need help, just bring it by.
Thanks George! I will give that a try. I just threw another code too, havent checked it yet tho
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Old Feb 12, 2009 | 11:30 PM
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you likely set a P0507 idle speed too high. the IAC motor is fully closed and the idle is still higher than the target idle. i had that when my LS6 intake was cracked.
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Old Feb 12, 2009 | 11:51 PM
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^^^thats the code it would normally throw if that was the case
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