# 1993 GMC Intake

**URL:** <https://community.cartalk.com/t/1993-gmc-intake/52060>\
**Category:** General Discussion\
**Tags:** gmc, 1500\
**Created:** [July 18, 2010, 3:53pm UTC](https://community.cartalk.com/t/1993-gmc-intake/52060 "2010-07-18T15:53:27Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![treoff](https://avatars.discourse-cdn.com/v4/letter/t/da6949/32.png) [@treoff](https://community.cartalk.com/u/treoff)\
**Post date:** [July 18, 2010, 3:53pm UTC](https://community.cartalk.com/t/1993-gmc-intake/52060/1 "2010-07-18T15:53:27Z")

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I was changing the air filter on a 1993 GMC Sierra Pickup with the 4.3 engine and noticed a pipe connecting the heat shielding from the exhaust manifold to the air intake plumbing. It seems like it is routing hot air from the exhaust directly into the intake system. Why would this be done, it seems a little counter intuitive?

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**Author:** ![edb1961](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/edb1961/32/122_2.png) [@edb1961](https://community.cartalk.com/u/edb1961)\
**Post date:** [July 18, 2010, 6:53pm UTC](https://community.cartalk.com/t/1993-gmc-intake/52060/2 "2010-07-18T18:53:27Z")

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There is a damper in the air cleaner assembly to redirect hot air (not exhaust) heated by the exhaust manifold for better driveability when the engine is first started.

Ed B.

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**Author:** ![treoff](https://avatars.discourse-cdn.com/v4/letter/t/da6949/32.png) [@treoff](https://community.cartalk.com/u/treoff)\
**Post date:** [July 18, 2010, 10:04pm UTC](https://community.cartalk.com/t/1993-gmc-intake/52060/3 "2010-07-18T22:04:26Z")

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That makes perfect sense, but because that circuit never “shuts off” wouldn’t that reduce power once the engine is up to temperature?

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**Author:** ![Caddyman](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/caddyman/32/23_2.png) [@Caddyman](https://community.cartalk.com/u/Caddyman)\
**Post date:** [July 19, 2010, 2:34pm UTC](https://community.cartalk.com/t/1993-gmc-intake/52060/4 "2010-07-19T14:34:16Z")

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There is almost always some means of regulating the temperature of the intake air. There is a control system there somewhere.

“Carb heat” is usually not needed for summer driving. (I realize it’s fuel injected) but it makes a big difference in the wintertime…

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**Author:** ![edb1961](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/edb1961/32/122_2.png) [@edb1961](https://community.cartalk.com/u/edb1961)\
**Post date:** [July 19, 2010, 3:28pm UTC](https://community.cartalk.com/t/1993-gmc-intake/52060/5 "2010-07-19T15:28:00Z")

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Once the engine warms up the damper closes and only cold air enters the TBI.

Ed B.