Question Air Induction Tubes on the exhaust headers

[RLloyd]

2005 4.7 has these tubes on the exhaust manifolds. What do they do and what purpose do they have? I know its part of the VVTI on the 2005-2006 engines but what do they use the presure for?

[nytrousboy]

05-06 tundras have an eletronic air injection system. (smog pump)

The air injection system is designed to introduce fresh air to the engine exhaust as it exits the exhaust manifold. Exhaust gases are at their hottest as they leave the combustion chambers. Introducing fresh oxygen to the exhaust at this point allows continued burning of the fuel mixture as it travels down the exhaust system and ultimately out the tailpipe.

It has nothing to do with the VVTI. (except that the VVTI motor might be dirtier than the old motor) which is why they needed to put a smog pump on it to meet EPA requirements for tier 2 emissions.

hope this helps...

[hybridtoys]

Those are air tubes, there’s just exhaust pressure going to the EGR, from the cyl, not much more than the ambient air pressure. It basically takes the exhaust as it leaves the cyl, and routes it around the back where both sides meet up and go in to the EGR, "exhaust gas return" where there's various sensors n jazz. But it ends up getting recyled threw the intake. Perty simple.
You can plug these off but then you’re goanna set the computer in to "fault mode" basically the computer has a baseline/generic program it reverts to if it has signals "out of range" you would be alerted by an engine light, and poor gas mileage since the computer is not getting all the information, o2's, barometric pressure, ambient temp, dew point, elevation, ect ect
Anyway hope that helps.

[nytrousboy]

The 2003-2006 tundra's do not have an EGR valve, and I dont think the 2000-2002 tundra's have one either...

It's for the air system.

[csawyer]

I think that was added to the system when the catalytic convertors were changed from a 3-stage to 2-stage. Had to dump air into the system for the computer to read the correct gas ratios and for emission requirements.