GMT 900 Trucks General Discussion 2007 - 2013 Trucks | General Discussion

Ported and polished TB, now high revs in gear?

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Old Apr 8, 2011 | 11:20 PM
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kc'skustom95's Avatar
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Default Ported and polished TB, now high revs in gear?

Hi guys i have a 2007 sierra crew cab 5.3 with a K&N CAI, flowmasters, and recently a P&P throttle body. Now the problem.....

I ported and polished my throttle body last night to a mirror shine in the rough cast areas. I did not touch the factory machined areas used for idle control. Looked great.... But now while im in gear and i let off the gas i get a high idle?
Kinda strange because while im at a complete stop the idle will be fine. I also noticed that while going down the road at the high idle if you put the truck in neutral the revs will go to like 2,000 and stay there with what sounds like spark knock untill you pull it back into gear.

I do not have a tune yet but and i assume this could be corrected with one?

And if I choose to get a mail order what will I need to tell them to adjust so they get it right the first time.
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Old Apr 9, 2011 | 12:11 AM
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How many miles.. Just need the computer to be reprogram because it thinks u put a new tb unit
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Old Apr 9, 2011 | 08:21 AM
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48k, And is there a relearn procedure for a new TB?
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Old Apr 9, 2011 | 08:27 AM
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That is strange.
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Old Apr 9, 2011 | 11:06 AM
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a "relearn" will do nothing but waste your time.

the truck needs to be tuned. the blade of the tb is actually opened more in stock form to let more air in to idle, the humps cause this. now that you have the humps removed the blade is still set at the same open position as it was with the humps, and it is going to idle higher bc it thinks that the humps are still there deflecting air when really its not.
more air into the tb the higher the rpm.

just my .02
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Old Apr 9, 2011 | 09:10 PM
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I ported mine and had the same issue for a few days. The ecm figured it out and adjusted to help smooth out those throttle transitions. Runs fine now fwiw
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Old Apr 9, 2011 | 10:35 PM
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Originally Posted by iamkeniff
a "relearn" will do nothing but waste your time.

the truck needs to be tuned. the blade of the tb is actually opened more in stock form to let more air in to idle, the humps cause this. now that you have the humps removed the blade is still set at the same open position as it was with the humps, and it is going to idle higher bc it thinks that the humps are still there deflecting air when really its not.
more air into the tb the higher the rpm.

just my .02
I did not remove the 'humps' I only sanded down the rough cast areas and polished them. I guess I need to drive it to work this week to see if it fixes it self. Its realy annoying at low speeds cause if you let off the brake the truck will ease it self up to about 20 mph.
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Old Apr 9, 2011 | 10:38 PM
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It will adjust itself if you drive it for 30 miles.. If you don't wanna wait just get a relearn test.. I F up and bought a whole new tb unit etc... When I just need a relearn test..
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Old Apr 10, 2011 | 05:55 AM
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i figured if you "p&p" your TB that means taking the humps out to make it all the same ID diameter. i didnt know p&p had two different meanings.
good luck
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Old Apr 11, 2011 | 12:41 AM
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P and P doesnt necessarily mean that you are removing ALL excess material. But it certainly means that youre going to improve it over stock, even if it's less than what some others would remove
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