It depends which one... I'm embarassed to say that I ran for over a year with a vacuum line off - I just thought the hiss was my new (at the time) hootin' tootin' throttle body spacer.

 

Did you ever find out what was making the hissing noise. My 02 tacoma does the exact same thing and is starting to drive me nuts as to what it is. By the way do you have am aftermaket air filter k&n, amsoil, etc. I have an amsoil so I thought that might be it.

Thanks and have a good one
Shawn

 

I have told you all what it is.....

Gadget

 

Well i opened up the air intake box, and really couldn't tell any difference. Now i would listen, then go open it up and listen again. Maybe if I had an extra hand where I could stand there and listen it might have been better, but from what did, I really couldn't tell a distinct difference. And if it is in the air box how to I get rid of it? Yes I do have an K&N air filter. Gadget how do I get rid of it?

 

I checked it out on my truck. You are not going to get rid of it.

The air intake for the engine is in that area and what you are hearing is the air being inducted into the engine.

If you do not off road at all, remove the airbox and then take out the elbow that connects the airbox to the inner fender wall. That will move the sound way forward and you should not hear it there anymore.

The airbox is connected to a snorkle and it goes back to the rear part inside the fender to help keep the truck from sucking in air.

 

I noticed a hissing sound at certian RPM's immediately after swapping out my OEM air filter with a K&N drop-in. The hissing would only last for a few seconds. Since I will probably be switching air filters soon I'll try & remember to re-post here once I do that.

 

It's your intake snorkel in the fender (stock).

It's usually louder on cold startup because the truck idles faster....

when it's warm, I bet it goes away.

It's even more pronounced when you do the Deck Plate Mod.

 

i know this is somewhat of an old thread, but i've started to notice mine doing this as well, definetely in the airbox, but not a natural hiss of air being inducted.. could there be anything in there that could mess up and possibly semi-clog the intake to a point that it alters the sound?

note that i hear it at idle only, when i hit the gas it goes away, least it sounds like it does.. might just not be hearing it anymore.. also, im pretty sure it only happens after my engine is warmed up, forgot to check when i cold started it this morning.

edit, i currently have the k&n drop in, took it out, same noise.. ran it with the airbox open, same noise.. didnt see any loose vacuum lines.

any ideas? or should i just take it to the stealer?

 

*bump* for the day crowd

 

is your air conditioner on?

 

nope, a/c is off as well as the fan for my climate controls.

 

Hey I just joined this forum after "googling" the hissing throttle noise in my truck.

I've got an 03 3.4 V6 Tacoma 4x4 and it makes this exact noise. You can hear it get higher pitched with higher rpms. I thought it was electrical at first. Mine got way more noticeable immediately after putting a K&N air filter in.

I don't want to take the elbow off but would trying to better seal the airbox make a difference? I mean with a K&N you don't have to change it for a long time anyway so you could even use silicone on the airbox lid. Anyone tried this?
And alternatively, can anyone tell me would it be worse if you went to an aftermarket cone style intake?

Thanks

 

I believe in your case it's just a regular air intake hiss you have to get used to because of the modification.

When I did the ISR mod and the deckplate mod on my truck (in sig), I began getting a pretty loud (kinda cool) hiss when I open my passanger side door when the engine is cold. Once the engine heats up, the noise seems to go away.

I believe the noise is just the engine sucking more into the new intake during warm up. I am also pretty sure that noise was always there, it just got amplified after the intake mod.

Sparknotes: Nothing to worry about.

Welcome to YT, BTW.

 

Not sure if I was hearing the same type of hiss. I recently had the Fuel Injectors cleaned at a local dealer and started hearing the hiss from the right (passenger) side when I was close to 2500 rpms. I was going to take it back to the dealer to find out what that noise was, because I tried to check everything speakers, air vents, loose change but nothing would make it go away.

I just happened to have a DMV smog check done a week after the service from the dealership and the Smog center must have corrected the idling on it the hissing went away. I noticed the hissing noise gone as soon as I drove out of the smog test center.

That's just how mine hissing issue was resolved not sure if its the same issue.
96-4runner-4wd-5spd-sr5

 

The Hissing is the air going into the air intake through the fender, It happens to me on cold mornings now that I have the True Flow air intake elbow kit. It can be loud (noticable) when the passenger door is open, but not enough when the door is closed(while I'm seating inside). No big deal.

 

I have the same proboblem on my 97 4runner, It started a few months ago. If I rev it up it goes away, but when it drops back to around 2500rpm it comes back and dam it can be annoying. My dads a good mechanic and the first thing He said when he heard it was, "hmmm son.. that sounds like a vacum leak or some debree stuck in there and its not geting good air flow" but who knows. im goona take the airbox apart and clean everthing and hopes it makes a difference. Sounds like I've got something in common with some people haha.