diablo

I have a header on my 22re that blocks off the PAIR tubes comming out of the head. My question is will this have any effect on the function of the EGR or are the 2 systems seperate?

peow130

That's where the EGR gets all of its info from..
So.. if the pair tubes bolt on, then bolt them on.

diablo

info, like the exhaust gases or ?

toyota4x4907

The EGR gets gas through a passage in the head. Notice how the EGR tube bolts to the head. The PAIR system is what is bolted onto the exhaust manifold. Thats where clean air from the intake is "injected" into the exhaust. They do not rely on one-another.

diablo

Thanx,4x4907 I wasnt sure if they worked or relied on eachother.

peow130

That makes no sense.
If this were the case, then your o2 sensor would read a constant lean..

toyota4x4907

It makes perfect sense. The PAIR system only allows air into the exhaust when the vehicle is cold and warming up. The air aides the cat converter in doing its job when its cold. When the vehicle is cold-warming up, its running slightly rich, so really it offsets it. Plus, the ECU knows that when its warming up, it will have more fuel in the engine and "more" air in the exhaust than what is actually going through the engine.

Sportsmanphil

EGR and PAIR are not related.

The EGR pumps exhaust back through the intake, which cools the combustion chambers. Exhaust gas has already burnt up the oxygen, when its pumped back into the engine its an inert gas and will not 'fuel' the explosion. This takes up combustion chamber space with air that will not burn, allowing the combustion chambers to run cooler.

The EGR is linear, allowing more inert gas with the more fuel you try to send into the engine. The EGR is off at idle and increases on a % basis with the throttle opening. Some are activated by vacuume (as your toyota) some use a 3 stage solenoid and some use a linear solenoid.

The PAIR system injects oxygen into the exaust while it reaches normal operating temps. This is similar to open vs closed loop as OBD1 vehicles do not have the sensors that later vehicles have to determine how much fuel to send when cold.

Too much fuel on a cold CAT can cause it to become damaged and reduce its life. In addition it causes poor emissions which cuts holes in the ozone and kills polar bears and brazilian spiders (< joke folks, no hate mail please) The PAIR protects the CAT and allows for friendlier emissions during cold starts.

pinoaktwh

That's not funny about the polar bears dude. I could care less about the spiders tho.

Just sayin

Sportsmanphil

If I lived at the North Pole with a .338 Lapua, we wouldnt have any more polar bears to worry about.