ovrebo1

When ever I'm coming to a stop my exhaust makes a fluttering noise right until I come to a complete stop or start accelerating again and it doesn't matter whether I've come down from 5th or I've rolled the truck slightly forward in 1st. The truck has a stock exhaust until after the cat, then it goes into a flowmaster that exits out to 3" all the way to the back of the bed. It has an electric fan, cam and battery intake swap. I can remember it making the noise I think ever since I did the exhaust and that was the very first thing I did before any of the other mods.

toyota4x4907

exhaust leak.

ovrebo1

no, it's not a leak

whokrz

Air flow meter it may be the flapper thing inside my 22re does it.

space-junk

iTrader: (1)

im guessing its a 3vze??
mine does that... but its got a magnaflow... i just chalked it up to the motor winding down and releasing all the backpressure...

ovrebo1

it's a 94 22re. I was thinking it was the air flow meter as well because I have messed with it. Is there anything I can do about it?

whokrz

Not that I know of I consider it a good noise it means it is functioning, they occasionally get stuck open causing the engine to run very rich without throwing codes. I had a 1985 22re that did it and currently have two 1990 22re that also do it. You can check to see if it is making the noise you are hearing by turning up your idle on the throttle body. Mine starts to flutter at 1200 rpm or so depending on its mood that day.

abecedarian

may be the PAIR system injecting air in to the exhaust to deal with the rich condition encountered during decel. You'll hear it more easily during decel since there's less exhaust noise from combustion.

ovrebo1

should I try and adjust it leaner than stock. Currently I have it set slightly richer. I set it back to stock the other day, but it still made the noise. I didn't try making it leaner. Whats the PAIR

ovrebo1

bump.

ovrebo1

You were right about the PAIR system injecting air into the exhaust. It never changed whether I leaned out the MAF or not. I narrowed the problem down to that valve that is under the intake plenum. Would the problem go away if I got a new one? Where can I find one? Are they rebuildable? What is the point of it?

I restricted the air flow to it by shoving a hose inside of the larger one and it made the sound that had been driving me nuts much less noticeable. Will this affect anything?

toyota4x4907

Thats the PAIR reed valve. Like Abe said, it lets air in at decel and cold start to deal with rich condition. It injects air into the exhaust to help the cat with oxidation and what not. Its part of emissions. Leave it on, buy a new one from the stealership or get one from the junkyard. The smaller diameter tubing might (if it actually affect anything) let less air into the exhaust which could have negative affects on your cat and emissions.

ovrebo1

I found this on another site. I think if I restricted the air to much it might cause the cat to be to rich and melt down.

late model (as of 85 or 86 I belive) 22re engines changed from a air pump to a pulse air injection setup. If you follow the small hose from the air box you will see it run into a round accumulator. From there it goes to a valve, and from there around the back of the head. Behind the head in the steel pipe is a check valve, from there it goes into the manifold. The head has pear shaped exhuast ports so that the air goes from the small pipes into the manifold and downstream to the cat. Its called Pulse Air Injection because the exhaust exiting the head into the manifold causes vacuum and sucks in air from the small pipes on the manifold. It works on the same principle as exhaust scavenging. Again, it doesn't use any power to drive, and is injected post combustion. At that rate, a stock air pump only uses 1-2 horsepower. It's main downfall on 22r's was the crappy air rail on the manifold that you could never get to stop leaking.

Anyway, the air injected to the cat is an attempt to maintain a 14.7:1 Air fuel ratio at the cat. It does its best work at that ratio. When cold the engine is running rich and the cat cannot reduce emmissions. So you inject air to get back to stoichiometric ratio, the cat works better, and it warms up faster, thus working even better. Once the vehicle is warmed up the valve under the intake will block flow of the pulse air. Air isn't needed once the engine is warmed up, unless you decelerate, when the throttle is closed, and the engine isn't in fuel cut yet. This time the engine is rich again, so they inject air to keep the cat happy and working. And to keep it from melting down from an overly rich ratio.

ovrebo1

Now that I know what it is, has any one on here rebuilt of repaired a PAIR system.

toyota4x4907

Good description!

ovrebo1

bump.