Ok so, I've been uncertain if my Power Vavle has actually been switching my manifold over. So I went out today, and checked to see if the shaft connected to the vavle along side the IM was moving, or switching over.

I would watch it as I gave it full throttle from the cable, close to redline, It did nothing. I was then moving it by hand to to see if it would change anything, when I moved the shaft towards the direction of the headlights, the sound seemed to be different. I'm not totally sure how it's supposed to work, but it seems that it's not. What are ways to know or test, if the Power Valve is operating properly? Thanks.

 

nope its not working. it should move just by blipping the throttle not just pushing it to red line. I know mine did.

Take the hose off and suck on it...if the valve is working it will move the lever (if you have a good vacuum line to the valve). If it isnt then you need to replace the valve. If it does work by sucking on it then you need to check all vacuum hoses first then electrical connections after that.

Lets see if someone makes my statements dirty lol.

 

First thing is to put a vacuum pump or syringe on the inlet tube to the gold colored dashpot in the picture. Pull a vacuum, i think it was like 3 psi, and see if the dashpot pulls on the valve and opens it. The vacuum should not leak down. If it leaks down the dashpot diaphram is broken (replace). If it doesn't try to push in the rod coming out of the dashpot. It should move in and out against the spring. If it can't then perhaps the valve itself is rusted or stuck closed due to deposits (clean). If all this is O.K. check for vacuum coming from the dashpot tubing. IF there is none, then you have a vacuum leak in the lines. the actuator solenoid (drivers side, lower right by firewall, below EGR) isn't working or there's a leak in the vacuum reservior ( vertical cylinder firewall side of MAF) or lines.
If you get through this there's a test for the solenoid that I don't have in front of me now, but it involves applying 12V to the solenoid connectors and then the port to the vacuum reservoir should connect to the port to the power valve and without voltage the port to the reservoir should be closed and the power valve port is open to atmosphere through the mushroom shaped vent on the solenoid.

 

Well, I replaced every vacuum line I could see, and still no luck. I tested everything, the Valve doesn't stick because I could suck on the line, & it would move. I do know it's none of the vacuum hoses, cause the're all new. The two vacuum lines in the picture under the EGR valve without hoses, have no vaccum at all.

I would pull the hoses off & feel, there is no suction what so ever. Now, the middle hose, has plenty of vacuum. I believe it goes the the Fuel/Charcoal Canister. What I did is connected the hose that is to the very left, closest to the red connector into the middle one, to see if that would move the valve. Obviously this is the wrong line to connect it to, just want to test it with some sort of vacuum, but sure enough, the vavle now moved. The shaft on the accuator switch would move towards the front of the car, and stay there. If I gave it gas, it would move back. I drove the car like this around the block, it didn't really feel any different. The powerband changed a Tad, as well as the sound, but no real change. What else should I check, to make it work. What is weird is those two lines having no vacuum at all. I believe that's where the problem lies.

 

just a WILD guess here.
one of those lines with no vaccum is probably a controlled vaccum source, so you wouldn't feel vaccum on it except under specific conditions which you aren't likely to be able to reproduce with the hood open.

 

I'm not exactly sure what you mean by this?

There should be a vacuum on the Yellow circled vacuum line at all times. That is the line that connects the rubber line on the otherside of the manifold to the front of the Power Valve. Even when I would floor it, with my finger on the yellow circled line without the hose on, it wouldn't have any suction. So what I did is I connected the Yellow circled rubber hose to the Red circled vacuum line, which I think is for the fuel canister, just to test it with some vacuum. Sure enough the Power Valve was functioning. I don't believe it was working 100%properly, because that's the wrong vacuum source. Something is just not right here.

 

It's probabably a faulty vacuum valve/switch. Either the brown or green one. I forget which.

 

Are those expensive to replace? Also, am I correct as in the Yellow Circled line should always have vacuum to it. Because it needs to, to have the Power Valve shut at low rpms. Cause when I hooked it to the Red Circled line, it would close the vavle, and then when I would give it throttle the valve would move back again, like when the engine is off. Is that how it's supposed to operate? When it's I have the vacuum lines properly setup, it does nothing.

 

Naw. You can probably go to a boneyard and look at almost any Nissan and fine them.

 

Bump...............anymore input? I went out & cleaned the the connectors alittle..........Still nothing.

 

^^^^^^^^^^^^^^^^^^^^^
Replace the green vacuum switch....Most likely the problem..

 

Look at post #4, what I don't get is why those two lines without the hoses on them have no vacuum at all, even when I give it lots of throttle.
I think that's where the problem is.

 

Could someone post pics of these vacuum lines, that are in the correct places. I think one or two of my lines may be mixed up. That may be causing the Power Vavle to not work. But I still don't get why those two lines in post #4 without hoses, have no vacuum ever.

 

are you sure you have both lines hooked up to the canister?, seeing this tread helped me fix mine because i had that line missing,also, there is a line that comes out of the gearbox that i dont know where it goes to, it is the one facing up in the middle of the tranny case, so far it is just sitting there, disconnected

 

That's the tranny air vent. It just comes up to a "J" shaped end that's attached to the front valve cover vent hose (from the intake bellows). It's supposed to be open. It vent air in the tranny when it gets warm to reduce over-pressure in the manual tranny. It's up high to prevent water from splashing into it.

 

Did you just run the engine to redline, or did you aggressively open the throttle? The power valve will only open if you open the throttle sharply.

 

Well, when I attched the vacuum hoses from it the wrong lines, to get some vacuum, it would move. In my first picture, the shaft would move towards the front of the motor & stay there. Then when I would give it throttle, it would start to move the shaft back, like when the engine is off. Yes I would floor it to redline. But it would even move under light throttle input. Is this how it's supposed to move & operate?

 

Could the non-vacuum to those two lines maybe be related to a crack/leak in the charcoal canister? Cause there is three lines coming off of it.