Loud hissing near firewall mid engine

[jprhome]

Hey all I've been trying to find where this loud hissing noise is coming from for weeks now and I'm beyond confused..

It's coming from behind the intake on the 3VZE. I've checked to see if there are any vacuum lines back there but can't seem to come up with any besides the recirculation that goes to the canister and throttle body.

I've tried reaching my hand around there while the engine is cold and running too see if I can get a change in noise by messing around with the hoses but I have no luck with that.

I've ordered a new upper intake gasket so I can pull the upper intake off and look around and see if I can pinpoint the issue only $4 for that. the upper has a new gasket already and the TB when I replaced my fuel injectors seals I got them inside the kit.

I've had some loss in power with the 4runner lately it's torque just seems to of left the house. I've also been dealing with a weird surge around 50-65mph at low RPM's in 4th gear or when going from a stop it just seems to have this drop back effect when accelerating hard which feels like the transmission but lately I've been stuck in the dark on the entire situation because it feel like it can be anything at this point and I can't seem to pen point anything on this rig.

 

[itgogitrev]

Is the hose for the brake booster secure? Does it seem like it struggles to idle?

 

[jprhome]

No struggle to idle and I've checked the hose running and couldn't find an issue. The hissing is coming from behind the engine down low.

 

[flyinhawaiian01]

Grab some hose and stick one side in your ear, then the other side down where you think its leaking. You'll find the exact area when it gets loud.

Pinpoint the area before you start throwing parts at it and taking things apart. I wouldn't be surprised if its the crossover pipe for the exhaust, and if it is, you may even feel some of that hissing air blow into your ear!!!

 

[jprhome]

Well just the other day I finally figured out what was causing the hissing.

The back two air plenum bolts (the smaller ones on the right side) the threads on the intake are gone so the bolts are just sorta sitting in there.

So this means picking up the right tap and some helicoils (hopefully in a kit to save money) since I do not have a tap set handy.

1 issue I cannot find the bolt sizes, just the part # for the bolts. I've also noticed the rear bolt is suppose to be a stud, yeah I'm guessing the issue was known by the last seller since they told me they just redid the heads.

Anyhow could anyone save me some time & money by telling me if they know what size these bolts are so I can pick up the correct metric repair kit?

 

[penbergm]

if you have 1 good bolt, take it to autozone or home depot and size it up.

 

[jprhome]

You're evil :tsk:

I assumed that's what I would have to do in this situation.