Need some help with Vaccum Issue

So ive been having a rough idle for a while now and get a p0441 code once in a while, when to toyota and ive heard that these evap codes are hard to diagnosis so what they do basically is they tell me i need to replace the entire evap system cansiter, etc everything. Clearly they dont know how to find the problem and since its so hard to find they just replace everything. My question is the VSV (Vaccum Switching Valve) is under the manifold correct? autozone said that was my issue, and also where is the purge valve as well? im gonna try to replace these valves to see if they change my idle cause its loosing vaccum it seems and causing it to run rich and rough.

 

The VSV under the intake manifold is for the EGR. VSV evap is over on the drivers side with all the other evap stuff

https://i972.photobucket.com/albums/ae201/SFD4x4/EvapBox02a.jpg

I'd just test it first. Good chance its something else. How old are your vacuum hoses?

 

The VSV can cause a rough idle?

 

Possibly. If its on when its not supposed to or you've got a leak, that could be a problem. I know if I yank the vacuum hose off the evap mine runs awful, a leak would have a similar effects.

 

It would sound like a leak cause I heard a kind of a hiss near the vsv

 

from the manual

 

Why don't you test the VSV before replacing it? You can also disconnect the vacuum hose and plug it, then you'd know if it's causing a rough idle.

 

How do I test it? It’s two hoses correct that go into it?

 

24 yo truck. Replace all vacuum lines. Easy to do just do one at a time. Also make sure to change any caps on unused vacuum ports.
That’s basically what the dealer will do plus a few possibly unneeded parts the over charge for the work.

 

They wanted to charge me 1k to do the entire evp system that’s a lot of money for some rubber hoses

 

The VSV either lets air through or blocks it. When you apply battery voltage it will do the opposite. Someone else can say if it's normally is closed or open when no voltage is applied.

 

50 bucks, a scissors, and a couple of hours. Protip: do one at a time

http://www.siliconeintakes.com/liquid-air-adapter/silicone-boost-vacuum-hose-p-590.html

 

Replacing everything is way harder than troubleshooting the problem and fixing it. My understanding of the Toyota evap system is that it first pulls a vacuum on the whole system. It does this by opening the vsv for evap and closing the vsv for ccv. If the system can't pull a vacuum down or it increases in pressure fast enough after pulling a vacuum, it sets p0441. This could be the vsv for evap not opening enough, the vsv for ccv stuck open, a leak in the lines, a leak in the canister, gas cap, etc. The dealer probably says replace everything because almost everything could cause this to set. I would start with the easy things, the vsvs require 12v and will click when they switch position from open to closed or closed to open. If those are good then smoke test for leaks. If that doesn't find the problem then a vacuum test would be my next step. Any auto mechanic should be capable of diagnosing this, if not, find someone else.

 

Still a 24 yo truck. Changing vacuum lines should be done about every five years. A minuscule leak can adversely effect engine performance.

Besides it’s a great chance to examine other components for wear and tear

 

Aren’t most of the hoses different sizes? Or could I just buy this?

 

Check the various diameters and buy accordingly. It really is a no brainer if you do one at a time.

 

ill check with the VSV and see what comes back and ill test all the valves.

 

The purge valve is statically closed and should hold vacuum on the intake side until commanded open. If it sticks open when it shouldn't it can cause a rough idle and the code.

 

The one under the manifold correct? Or by the canister

 

Manifold one is called the purge valve and it is closed at all times until commanded open

Canister one is called the vent valve and its the opposite. Normally open until commanded closed

If the vent valve near the canister sticks open it will fail a leak test (small leak/large/gross/etc) but it won't usually cause running symptoms like a rough idle.

If the purge valve at the intake manifold leaks that's like a direct vacuum leak through the canister straight into the engine. It will cause a rough idle. Since it can't hold vacuum during a leak test it can code as well.