acceleration hissing sound, CANT FIND IT!

Some one pleas help. I just bought a used 2006 Toyota tacoma prerunner with 75k miles on it. Only one owner perfect condition. There is a very annoying hissing sound it makes only when accelerating under a load(meaning it only douse it when in motion). It only takes about half throttle to do it when its cold, and when its at running temp. I almost need to floor it to get it to happen. Took it to a Toyota dealership and after having it for two days they said they we're not shore what it was. I have looked all over for exhaust leaks& not quite shure where to look for vacume leaks. Can't even tell if it is conning from the exaust, transmission, or engine areas. Im going to go insane. Someone pleas help. The only way I can explan the sound is it sounds like a almost pulsing air sucking sound. On top of that the truck has a ticking almost exaust leak sound when its not hissing but I have seen alot of posts of people saying that is just how the engines sound cause of the exaust manifolds.

 

No. Every thing is oem.

 

I had a hissing during acceleration in an Xterra I used to own, took it to the dealership and they couldnt find the problem. Turned out the belt was starting to shred and slapping against everything, it boggles my mind how the dealership didnt find it but i fixed it and never had another problem. Nissan just makes crappy belts.

 

I examined the belt along with everything els that I can see. If I keep the door open when accelerating it sounds like its conning from underneath I think.

 

I had this exact same problem the other day with my 2010 PreRunner. It ended up being a plastic grocery bag that was hung on my skid plate. So as I accelerated moving forward, the bag would make this horrible high pitched hissing as the wind whipped through it. It was driving me crazy until I saw what it was. Here's how I fixed it.

Step 1: Using 1 man sized hand, gently grab the plastic bag where it is caught on your skid plate.

Step 2: Pull on plastic bag until it comes loose. If bag does not free easily, use 10 lbs. force until bag is freed.

Step 3: Place plastic bag in trash receptacle or recycling bin if you wear sandals.

 

Maybe an exhaust header leak. Had one between the header (or manifold) and the downpipe, but that was on an older Ford. I don't know for sure that our trucks have that type of donut gasket. Carefully feel for warm air escaping from that area, obviously after the truck has cooled off so it isn't burning hot.

 

I have spent almost more time under my truck than in it looking for this hiss. I have even had my wife powerbrake it to get the engine torque to twist the engine & tranny to exspose the possible exaust leak/ tranny / vacume hiss. Checked every square inch underneath the truck& hood. I dnt want to take it to Toyota again for them to charge me 90 dollars to hook up there computer& tell me there is nothing wrong and they don't know what to tell me. It will only do it when moving. When cold it will do it from the verey start of moving. Another clue that may help is that when going up a grade on the gas if on a curve at the beginning of the curve it will hiss and at the end of a curve it will hiss. Not all the way threw the curve. Weird

 

I think I have this same problem on my 01 3.4 its driving me nuts

 

Check around the housing for the air cleaner and see if it is snapped together properly. I had a Plymouth neon that would do what you are describing. only it was the gasket for the air cleaner that had a crack in it and would hiss. I think the Toyota's have a gasket built on to the air cleaner.

 

Not a bad idea, I just pulled the air filter out to do Maby I didn't put it back in right

 

Sorry to bring up an old thread but did you find the problem? I think my dad’s truck is having the same issue right now.

 

I didn’t get to the bottom of it, however, the noise never turned into something other than a noise. Truck ran great to the day I sold it.

 

An exhaust leak isn't going to hiss, it's going to pop in time with the RPMs. A vacuum leak in the manifold isn't going to get louder on acceleration (in fact the opposite; as manifold vacuum decreases the more the throttle plate opens).

Check for plastic bags.

 

Can confirm no plastic bags LOL.

 

That's good to hear and sorry you sold your truck!