Air intake question.

[pro17]

lol back when my truck was TBI an inspector actually made me walk across the street to a parts store and put the tube on before he would give me a sticker. It hadnt had a tube for 20 years.

 

[Jack Schneider]

You can kinda see the filter in this pic

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[Jack Schneider]

lol back when my truck was TBI an inspector actually made me walk across the street to a parts store and put the tube on before he would give me a sticker. It hadnt had a tube for 20 years.

Lololololol

 

[RichLo]

honestly, it would be fine for a little while like that but it is in the beginning stages of failing. Just like everybody else has said, it really doesn't serve any practical purpose and the original design was to satisfy new car requirements (Like the AIR pump of the 80s... exhaust had to have a certain level of oxygen so they just pumped fresh air into the exhaust without doing anything else to the engine).

I would personally just gut it and forget it, but that's just me.

 

[Jack Schneider]

Well I’m happy for now, this time it was open almost all the way.

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[Schurkey]

I'm really surprised they kept that on as it's more for carbureted engines that need warm air to open the choke quicker. I removed mine completely when i installed a CAI. Truck runs no different without it.

The heated air intake has NOTHING to do with choke function. That's not how choke coils were heated.

it really doesn't serve any practical purpose

Of course it serves a practical purpose. When working as intended, it absolutely prevents throttle-body icing in high-humidity, cool weather. Throttle icing is particularly obnoxious at about 40--45 degrees if there's high relative humidity.

The heat stove/snorkel deal is intended to keep the air cleaner fed with air at about 100--120 degrees, somewhat depending on year and model. The snorkel will open or close to maintain that approximate temperature.

Back when they were vacuum-operated, folks would disconnect them in the summer, then re-connect the vacuum hose for fall/winter/spring.

A secondary benefit to the heated air intake is that they help a bit with fuel vaporization, along with preventing throttle icing.

(Like the AIR pump of the 80s... exhaust had to have a certain level of oxygen so they just pumped fresh air into the exhaust without doing anything else to the engine).

Air was pumped into the exhaust so that the fiery-hot gasses would continue to burn, dramatically reducing HC and CO emissions. In fact, many engines were run deliberately too-rich, which lowered combustion temperature to reduce NOx emissions, and then the AIR pump would support additional combustion of the HC and CO in the exhaust manifold. The extreme example of this was the Mazda Rotary, which had a "Thermal Reactor" (i.e., a bigass insulated iron exhaust manifold with huge interior volume) where the exhaust continued to burn due to the added air. The Thermal Reactor was still used in 80 or 81, but was replaced with a catalytic converter after that.

 

[jkeaton]

 

[Tavi]

Of course it serves a practical purpose. When working as intended, it absolutely prevents throttle-body icing in high-humidity, cool weather. Throttle icing is particularly obnoxious at about 40--45 degrees if there's high relative humidity.

The heat stove/snorkel deal is intended to keep the air cleaner fed with air at about 100--120 degrees, somewhat depending on year and model. The snorkel will open or close to maintain that approximate temperature.

Back when they were vacuum-operated, folks would disconnect them in the summer, then re-connect the vacuum hose for fall/winter/spring.

A secondary benefit to the heated air intake is that they help a bit with fuel vaporization, along with preventing throttle icing.


Air was pumped into the exhaust so that the fiery-hot gasses would continue to burn, dramatically reducing HC and CO emissions. In fact, many engines were run deliberately too-rich, which lowered combustion temperature to reduce NOx emissions, and then the AIR pump would support additional combustion of the HC and CO in the exhaust manifold. The extreme example of this was the Mazda Rotary, which had a "Thermal Reactor" (i.e., a bigass insulated iron exhaust manifold with huge interior volume) where the exhaust continued to burn due to the added air. The Thermal Reactor was still used in 80 or 81, but was replaced with a catalytic converter after that.

I was always under the impression this was an issue which only pledges carbureted induction. Due to the venturi affect. And that EFI and TBI were rather unaffected.

 

[Schurkey]

TBI would be nearly as affected as a carb. The fuel is sprayed above the throttle plates, so it's vaporizing and cooling the air as the air passes around the throttle. The cooled air deposits ice on the throttle blades, and maybe within the Idle Air Passage. The ice disrupts the flow of air, leading to unstable idle and poor power.

A difference is that the ice wouldn't block the idle feed passages of the carburetor idle circuit. A carb'ed engine would readily lose power and stall as the idle circuit openings became encrusted with ice. The TBI would still be squirting fuel.

This is another reason that the "Big Block" TBI adapters had hot water (engine coolant) routed through them--to provide another source of heat for the throttle body.

Port fuel injection would be less susceptible to throttle body icing. No fuel prior to the throttle, so very little cooling of the air.

 

[pro17]

TPI and LT1 throttle bodies have ports flowing radiator fluid them to keep the TB hot, so I assume it's the same principle (icing on throttle blades) and not just a carb and TBI thing. I bypassed the one in the camaro, and cut off the ports on the one in the truck. Hot air really isnt needed in texas.
https://www.thirdgen.org/tech/coolantbypass.gif