[superfluid]

Hey all,
I have a 1990 4WD with the 3VZ engine. When I rev the engine up and then release the throttle, a low rumbling sound comes from the air filter compartment. It almost sounds like a growling. It happens all the time and the air filter is clean. Is this normal? Any ideas as to WTF this sound is?
Thanks in advance.

 

[StevetheRiddler]

I believe that sound you described is the EGR system kicking in.

 

[pee_cup]

I think I know what you are talking about. It sounds like Jake Brakes. and will make its sound at idle for a few seconds and then its off. I always thought it was the Vane Air Meter flap sticking open just a tad. What do i know.

 

[shoes1382006]

check to see if everything is connected!

 

[superfluid]

I think that everything is connected. If it is the EGR system is this normal? The check engine light came on for about 10 minutes the other day as well. I dont know if the 2 are related, maybe a dirty O2 sensor or something? Thanks for the replies.

Oh and yes pee_cup, the sound is very similar to Jake Brakes.

 

[StevetheRiddler]

I think it says in the Toyota repair manual that the sound is normal. My 22RE makes the same noise.

 

[ovrrdrive]

That noise comes from the flap inside the afm and is normal as far as I know. Mine has always done it, but it may be getting louder with age...

I wouldn't worry about it.

 

[Mushroom_Toy]

Yup it's normal or either you have a tube connected only halfway or not at all.

 

[Vicoor]

The noise is normal..............

But it has nothing to do with the EGR or AFM. The noise comes from the pulse air injection system. Under decel conditions a valve opens that let air pulses to "drawn" into the exhaust stream to lower HC emmisions during decel.

 

[podracer169]

So what does it mean if pulse air injection is happening all of the time ( Not just on decel )? I can hear mine going 100% of the time - even in idle.

 

[lumpybblbiscuit]

when i drilled another hole in my airbox for increased flow my truck makes a noticable noise like what you describe but it goes away after a few seconds. Did you or the previous owener mod the airbox?

 

[podracer169]

I actually removed the box and installed a cone filter. Placed a small filter over the air injection tube. Just cant figure why it would make that pulsing noise all of the time.

 

[lumpybblbiscuit]

The stock airbox has a tube in the bottom to cut down noise as with almost every car on the road today. When you take them out it makes it easier for that noise to hear and thats why we do when the intakes are freed up. As for the source of the noise i couldnt tell you, only that its normal and there is no problem