DupermanDave

I fized my high idle in the previous threads. I got a new throttle body.

Now I have a hissing noise coming from the intake manifold. It only hissed every once in a while. I can't narrow down the spot, but it sounded like a gasket was letting air past, so I replaced the gasket. Still nothing.

My idle will be fine, and then sometimes at stop lights it will slowly climb up and up to about 1100 RPM, and then drop back down to normal/

It definitely SOUNDS like a vacuum leak, but I can't narrow it down. I changed all the throttle body gaskets, intake manifold gaskets, checked hoses and tried feeling around for an air leak. I can't find it. I need some hints or clues. The hissing, for all i know, could just be the belts and my ears are just playing tricks on me since I can't stick my hole head into the engine bay and listen around.

eightnine

Try washing the engine bay looking for air bubbles on the hoses

DupermanDave

I tried that. Tried squirting and dumping soapy water on the hoses and gaskets. Couldnt see any bubbling or any water being sucked in. Also couldn't notice a difference in the idle.

toyota4x4907

Try starter fluid instead of water! Go over all the vacuum lines.

Could be the PAIR system working. It kind of makes a hissing sound and its connected to the air filter housing and the valve itself is right below the intake manifold. That woldnt really cause it to idle up though.

I kind of dont think its belts since you're getting the idle up symptom of a vacuum leak. Did you check the the EGR-intake plenum gasket?

There are a ton of little vacuum lines on the 22re. are you SURE you checked them all?

DupermanDave

The rising idle could be a misadjusted TPS. I set the TPS to spec when I installed the new TB, but when the TPS is unplugged the idle no longer surges. So they may be separate symptons for separate problems.

I did check all vacuum lines. Had the intake manifold off to make it easier. That's when I also changed the gasket.

DupermanDave

I readjusted the TPS (seems to be good now) (still getting a check engine light with TPS code though, but I'll fix that later.)

I finally found the source of the hissing. It's the front part of the throttle body. Where the throttle body meets the intake manifold. I poured some more water all over that area and found it's either the front intake area or the front area of the intake manifold/plenum.

I've already replaced the intake manifold and plenum gasket (first with a paper gasket, then with RTV, then with a paper gasket again). That didnt fix it, so I got a new throttle body gasket (the square one) for the throttle body. I've also got the throttle body bolts on tight (didnt torque them to specs, if there is one)

-edit-

Found the leak. It's at the intake manifold, where the throttle body meets the intake plenum. This is the one where I replaced the gaskets 3 times (ugh!) So what now? Should I try another gasket?

Matt16

Take the snake out of the engine bay perhaps?





Apparently, they like the warmth.

KevinInSac

Simple, but make sure your hose isn't cracked. If it's old a crack may surface easier than you think.

DupermanDave

I ran over all the hoses today. It's seeming like it's still a gasket.

DupermanDave

Should I use RTV again and this time gob the stuff on there so it's thick? Also, if I go that route, should I also let it cure fully before installing the bolts, ot should I try putting everything together right away?

Junkers88

I just replaced the gasket between the TB and the plenum with some silicone based RTV last week. I followed the directions on the back but instead of bolting it all down right away I let the RTV sit and cure for about 30 minutes then tightened everything down. No leaks.

DupermanDave

That's the way I did it last time. Let it cure for 30 minutes, then tighened everything down. That didn't appear to work (though at the time, the elak could have been at the throttle body. I should have documented all this)

I guess I'll try it again. How much RTV did you use? just a thin stream of it? Or did you smear it around and cover the surface area of the intake?

I used the red RTV, because I know it gets pretty hot on the intake manifold. Is this the right color to use?

Junkers88

Where exactly did you put the RTV? I used RTV instead of the little square paper gasket thing that goes behind the throttle body in between the TB and the plenum. I pulled it off initially to get to the idle air control valve in an attempt to get it cleaned up.

The RTV I used was sort of clear like watered down milk (it was what I had on hand when I realized the gasket I bought was the wrong one). I sort of smeared it all over the mounting surface of the back of the TB, let it sit for a while, mounted it but didn't tighten the bolts all the way, let it sit for a few more minutes and then locked it down.

I started it right away and don't have any problems.

DupermanDave

I put the RTV on the intake plenum, let it sit, and then put the throttle body/intake manifold over it and losely tightened the bolts. after 3 hours I went and fully torqued them down. I didn't smear it around. I just left a bead or a line of it and left it at that.

DupermanDave

Would it hurt to goop the stuff on there? How thick should it be once it's fully cured? 1/4" 1/8"?

Junkers88

Once the RTV is cured it should be no thicker than the thickness of the original gasket.

DupermanDave

That's hard to judge, because the last gasket I had on it was about twice as thick as the one I have on it now. The one I have now is a felpro. Not sure what the older one was, but the older one was a thick cardboard gasket we got with a headgasket set.

I'll try and work on it tonight and smear it all accordinly. I'll do it like the RTV says to.