Re: vacum sensing valves/ high idle

Posted by 4Crawler on September 14, 2008 at 15:10:06:

In Reply to: vacum sensing valves/ high idle posted by ted wilson on September 14, 2008 at 08:03:20:

: I have a 92 toyota 4x4 with the 22 re engine with california emissions. on top of the valve cover are 2 (vsv) vacum sensing valves. Can anyone tell me what they are for? they both have little filters on them and some electronics wired to them, one of which make a straw slerping noise and when I take the filter off it goes away. I tried to get just a filter but toyota wants $80 for it. Anyways after I drive for about an hour I notice the truck idles a few hundred rpm too high and I think the VSV or something in the vacum system/EGR system is related to this. Does anyone have any input on this problem?

Actually, that is Vacuum Switching Valve (VSV). Think of them as a relay for vacuum, that is when energized, vacuum from the engine is switched to the output port on the VSV to operate something. There are multiple VSVs, so best to follow the vacuum lines and see what it connects to. One bumps up the engine idle when the A/C (if present) is on. One runs to the fuel pressure regulator to modulate fuel pressure. One sends vacuum to the EGR modulator (on later model vehicles). One hooks to the charcoal cannister (on later model vehicles) to pull gasoline fumes out of it into the engine. The air filter is there to allow outside air into the output line when the VSV closes and keeps dirt from getting into the VSV.

The one making noise may be hooked up wrong (input and output swapped) and thus creating a vacuum leak. Filter can usually be cleaned, it is just some felt material inside the cap.

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: : I have a 92 toyota 4x4 with the 22 re engine with california emissions.  on top of the valve cover are 2 (vsv) vacum sensing valves.  Can anyone tell me what they are for?  they both have little filters on them and some electronics wired to them, one of which make a straw slerping noise and when I take the filter off it goes away.  I tried to get just a filter but toyota wants $80 for it.  Anyways after I drive for about an hour I notice the truck idles a few hundred rpm too high and I think the VSV or something in the vacum system/EGR system is related to this.  Does anyone have any input on this problem?

: Actually, that is Vacuum Switching Valve (VSV).  Think of them as a relay for vacuum, that is when energized, vacuum from the engine is switched to the output port on the VSV to operate something.  There are multiple VSVs, so best to follow the vacuum lines and see what it connects to.  One bumps up the engine idle when the A/C (if present) is on.  One runs to the fuel pressure regulator to modulate fuel pressure.  One sends vacuum to the EGR modulator (on later model vehicles).  One hooks to the charcoal cannister (on later model vehicles) to pull gasoline fumes out of it into the engine.  The air filter is there to allow outside air into the output line when the VSV closes and keeps dirt from getting into the VSV.

: The one making noise may be hooked up wrong (input and output swapped) and thus creating a vacuum leak.  Filter can usually be cleaned, it is just some felt material inside the cap.



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