TVV, what does it do, can I cap em off?
 

I just noticed that both my TVV nipples are broken off. Can I cap it? Where do the vacuum lines go and are they necessary? I don't have any loose vacuum lines laying around the engine bay. I think the PO did some custom work ;)

Are you referring to the EGR TVV? Where is it located? I know where the EGR TVV is, but where is the one you're talking about? If it's the one on the back of the manifold, it's for EGR. In which case, you don't need to cap it off. It's not affecting anything the way it is. But, you will need to do something about the EGR.

Yes it's the one at the back of the manifold. Both nipples are broken off and I was worried it was leaking vacuum. I would like a functioning EGR system. I was wrong before, I do have a charcoal canister and there's a vacuum line straight from the TB to it, which I thought was supposed to come from this VTT. I will await response but continue to dig thru posts and manual pages to find a diagram.

Oh crap. I think you're right there, bro. Yeah........the EGR has a vacuum switching valve.....different than the thermal vacuum valve. It's somewhere on the pass side of the motor. Terribly sorry. However, the TVV still doesn't present a source of vacuum loss. But, it does make your EVAP system inoperable. Yeah, I'd fix that bugger or replace it. There's ways people have repaired it on the forum. Run a search on TVV repair.

ps. I was originally thinking of the early 22re's when I made my first post. Again, sorry. Atleast your truck didn't blow up from my blunder.....:D

How it works.......

http://www.autoshop101.com/forms/h62.pdf

Nice link- I appreciate it. If I understand correctly, the TVV opens up when warm allowing the purge port on the charcoal canister to dump into the purge port in the throttle body. This way, when the engine is warm and in closed loop, the engine can manage the extra vapors properly.

So.... The PO has a line that goes directly from the charcoal canister purge port to the throttle body, bypassing the TVV. This would cause extra vapors to get in the TB when it aint supposed to. I guess I let it vent to the atmosphere and cap the TB port until I can come up with another one, or fix it next time I take my plenum off. Thanks thook.

Correct!

You should be able to pull the TVV without removing the plenum, iirc. I use a plumber's basin wrench to remove the sensors, etc. back there. It reaches straight down at the [sensors] and approaches the hex head at a right angle. Sometimes you have to use an extra length of small, metal tubing or something as a cheater bar. They do get stuck. Anyway, I know it's not real easy to get back there, but it's doable. Easier than yankin' the plenum.

I don`t know if this will help or not, but my 86 22RE has a vacuum line coming off of the throttle body and going straight to the charcoal canister. I don`t know if the 3.0 is diferent and has a TVV in that line or not, im just throwing the info out that it may be correctly hooked up, but im not sure ???.

So does my 22re........and, it's an '86. So, it won't hurt to have it directly to the TB, but I believe the design change was made for a more optimal system. Fuel is more vaporous when it's hot, and it might make for a more efficient warm up cycle. Don't really know........jus' speculatin'.

Oh, but definitely on this vintage of 3.0 (atleast....earlier might be different. don't know) it's routed to a TVV. See the link, eh.

drew -

Your description of the TVV / Evap canister is correct. Kudos to your prior owner for bypassing the bad TVV (retaining the emissions benefits) rather than just plugging the line from the throttle body. But since you are getting canister contents when the engine is cold it might affect cold operation (running way too rich with throttle open).

Of course, since your TVV is bypassed, it is not a source of a vacuum leak. If you just removed the line now connecting the canister to the throttle body, that would be a vacuum leak.

Many have had success repairing the TVV, but I found that the plastic top (of which the nipples are part) got so brittle that I was not able to repair it. It's only about $65 at the dealer, but not easy to get to (as you can see).

Try Nix99 for used Toyota parts. They're on the web.....out of Washington. DeathCougar, a mod here at YT, works there. Tell him I sent you, and ask him where my royalty check is. It's been over a month now.

Thanks to all who've replied. A new TVV part number, for anyone interested, 90910-12075 and the cheapest I can find it is $94.20 from 1stToyotaParts.com At that price I will keep the line directly to the the TV until I notice driveability issues. Otherwise I will try one of the fixes found here on this wonderful forum.

Edit: I'll check with Nix99.

Ask for Josh........aka DeathCougar. Tell him you're from YT......thook sent you.

Hold on....he wants a TVV/Thermal Vacuum Valve(a.k.a. Bimetallic Vacuum Switching Valve/BVSV)not a VSV(Vacuum Switching Valve). HUGE difference in price. 1stToyotaParts wants $44 for the TVV.

See my recent post here from another thread. Notice part labeled 23262 below is the one we're talking about.
Attachment 187200
http://personal.utulsa.edu/~nathan-b...74layoutan.pdf
Attachment 187201
https://www.yotatech.com/attachments...se-diagram.gif
http://i173.photobucket.com/albums/w...iusA/hose2.gif

Well, we all did say TVV/thermo vacuum valve. I guess he gots confused. Kind of you to point out the price difference. I did not look up his researching myself. Nevertheless [drew], Nix99 does have good used parts at better prices than brand spanking new. Just whatever you want, though. Brand new IS nice.