my power valve seems to only open sometimes under WOT. The times that it doesnt open it takes up to 5 seconds to actually gain enough power to accelerate.

 

some how i submitted without finishing, anyways is there a way i can force the valve to be always open?

 

is this on a VG or VE?
and it's not your power valve that is the problem.
sounds more like a transmission that is dying

 

its a vg, manual, and its not the transmission dying. its the motor trying to get more air than it can.

 

why do you think it's the engine needing more air?
and that is not what the power valve is for anyhow

 

doesn't the power valve open up 2 more corridors for air flow at higher rpms? for example, in neutral, give it wide open throttle. the pv opens and motor revs up just fine. do it again if the pv does not open the motor will "pause" around 2.7k-3.3k for a few seconds and then take off.

 

the power valve opens at >50% throttle when under 3500ish RPM, to assist in torque production. It lengthens the effective port length. when open at all ther times, ports are from the intake valve up to the are just under the "NISSAN V6 3000" sticker. When the power valve butterflies close then the port length extends in pairs of three back to those 2 little tubes you can see running left-right between the area where your ducts branch off just after the TB. Longer port length aids in torque when RPM is low, for some reason.

 

IMO - you can disconnect or block the operation of the power valve and there should and must be no detectable "pause" in the free rev operation of the motor with no load - if indeed you have such a "pause" during no-load "revving" conditions then you have a serious problem elsewhere.

Note:

1. THE PV's normal condition is actually "open" - ie - both input tracts are connected together.

2. The PV solenoid is energized (and thus the PV actually closes to ensure a longer intake port length via the application of vacuum from the vacuum surge tank) as a function of engine load and not only speed - ie engine load as defined by a situation of low engine speed and high air intake volume

 

When i move the pv to the position it enters in WOT. The motor runs fine
it when its in its idle condition when it screws up

 

well for one thing, you can test it.

start motor
open hood
prop it up with a stick because we all know your hood struts don't work, neither do ours. it's OK. heh
look at power valve while yanking up on the throttle cable, and make sure you pull it FULLY or at least half. You should see the power valve acutator move.

if the sucker moves, it works. check your ECM codes regardless. check your plugs. check your pcv valve (it operates on vaccuum.. can bog down engine in certain conditions)
check for vaccuum leaks

take us a video too.. that'll be the most helpful thing aside from the visual check of power valve funciton

 

sometimes it moves sometimes it doesnt, when it doesnt is when it hesitates.

 

well how do you know if it's working when you are driving and... your hood.. is ... closed? or have you taken the hood off for onroad diagnosis purposes?

also making the thing stay open at all times is actually not going to help. In fact, if your power valve isn't working, it's going to stay open all the time... because most of the time it is open. if you lock it open well... there goes your low end (some of it anyways). So if your power valve really is the problem, then sticking it closed is not the answer either, because that costs you high end. And we alllll know that a VG and High End are not the best of friends. In fact, they downright hate each other.

Long story short.. how do you know for sure it's the power valve malfunctioning on the road?

 

well i have these two things you set the wheels on, not sure what they are, but you can run dynos on them. and this is when i can look to see.

 

So you are actually watching the operation of the PV while the vehicle is sitting on a dyno? (as opposed to the "neutral" you mentioned earlier.........)

If you want a solution to come from people that do not have the vehicle in front of them and must base their suggestions on your description of the "problem", then you have to be absolutely clear on the conditions under which you are experiencing the "pause" around 2.7k-3.3k for a few seconds and then take off."

Stick to facts and do not put your own interpretation/spin on what is happening - the simple fact is that no matter what and how funky that PV is, there is simply no way it can be the cause of a "pause" of any duration while free revving that motor - I say again - no matter what


Pull the electrical plug out of its socket on the PV - you now have it permanently open (tracts connected together) ............... can you rev the motor and have no hesitation?

Remove the only vacuum hose on the PV bellows and connect the hose coming from the vacuum reservoir (that is currently connected to the PV solenoid) directly to that bellows - you now have the PV permanently closed (tracts independent) - can you rev the motor and have no hesitation?

 

when i plug the pv. Hesitation, When i use a screw driver to hold it back, no hesitation. there is no electrical plug

 

Come now - there is a green electrical plug on the PV solenoid driving the PV vacuum lines located just under the actual PV bellows (follow the only vacuum hose on the PV bellows to the PV solenoid and you wil find it there)By doing what?

 

ahh ok so thats what opens it, that must be bad. but i plugged both ends with well. PLUGS

 

I can only repeat my earlier assertionAre you quite sure that you actually successfully blocked the vacuum hose that came off the bellows during your tests? - I have to ask because if its not properly blocked, you will force a heap of fresh air into the motor at the exact moment that the PV solenoid is actuated and that can indeed cause a hesitation while the ECU tries to make sense of that uncatered for situation.

If, according to your tests, you do experience a "pause" as earlier described when the PV is at rest it can only be an indication that you have a blocked/partially obstructed tract to one bank of cylinders......................................... . which I doubt.

 

helps:

I have ran both my maximas (VE and VG) with the power valves disconnected,I felt absolutely no difference in either cars performance with the valves connected/vs. disconnected.

In short,you need to look elsewhere for your hesitation issue.

A good place to start would be inspecting and/or replacing all your 12+ year old vacuum lines.Next would be inspecting/cleaning all the electical sensor plugs/connectors for signs of corrosion(greenish looking crap) and/or looseness.(bad connections) this includes your injector wire connectors too.

All the above mentioned can cause intermittent hesitation/rough running of the engine.

 

im not sure why all of you assume things such as my Hood shocks or my vacuum lines are not in working order, both have been replaced along with many other things. I am positive that that it is the power valve that is the culprate and my question was How can i keep it open. as for the connectos i cut them all off and replaced them with new toyota ones which seem top be more organized and durable.

 

mine work

 

You have been a member here for 11 days,so the history of what you have done to your car is unknown to us,so in future threads,either give us a list of what you have done in the past so we know,or try to give us a little leeway when we suggest fixes that you have already done.

Try not to bite the hand that feeds you.



The power valve is a minuscule part in the grand scheme of how these engines run,imo they serve virtually no purpose as to the engine running characteristics,and i have proven this theory by unplugging this device/then driving each of my maximas for an extended period of time,i observed absolutely no difference in the engines performance.

But if you are dead set on your theory of the valve being the problem,just disconnect the vacuum valve from the internal butterfly,then use a zippy tie or some other suitable device to shim the butterfly open.or re-route the vacuum line going to the valve itself to a constant vacuum source.

Please let us all know if shimming the p/v open fixes your problem..

 

it's a jooooooke. mine failed in july. they were a little weak since spring but finally gave out over the summer. same with my brother's toyota. it's just one of those graceful signs of aging... where you have to keep a broomstick in your trunk. i started keeping one after i was working on something under the hood and my hood thonked me on the head..

 

WTF is wrong with you people?! My hood shocks work!


1. if you want to see if it is the power valve solenoid or not, stick a test light on the wires going into the solenoid, and stick a vacuum gauge on the PV end of the solenoid's vacuum line.

2. if the solenoid is working, then check the PV itself. disconnect the PV's vacuum line and stick a hand vacuum pump on it and see if it stays open when you pull a light vacuum on it. often the rubber diaphragm inside the PV will dry rot and start to leak, preventing the PV from opening as it should.

3. if the solenoid isn't getting vacuum all the time, then you need to start looking upstream at the surge canister and things like that. it's possible your check valve or the surge canister is broken or damaged or whatever. see if all that stuff is in working order.

4. if the solenoid isn't getting power, then it's an ECU problem. swap with another eCU and see if that fixes it.

5. if you simply want to hold the power valve open/closed, then just use a zip tie or baling wire to pull it open/closed and hold it in place.

6. My opinion is that you've got something else wrong with the engine, whether its a vacuum/manifold leak, fuel problem, ECU problem, or something along that line. the power valve probably isn't really causing the problem, but is merely a symptom of the underlying problem. i.e. why is the engine not getting proper vacuum? misfire? leak? etc.

 

I had my power valve actuator fail about a year ago, the vacuum was applied, but the actuator was not moving. I did not notice any change in engine performance, just happened to notice it was not moving when checking other things. Turned out that the internal rubber boot was torn, since a replacement was difficult and expensive to come by, I opened it up and repaired it myself, it is working fine now, but again, I didn't notice any difference in performance at any RPM range once I got it working.

To the OP, if you are noticing a hesitation, I suggest you look elsewhere, the power valve isn't going to cause your problem, but the power valve not operating properly may just be a symptom of the real problem.

 

hmmm -vvv
What this means is that the power valve adds a paltry 8 lb/ft in the already-strong low-end torque range of the VG motor. At that RPM, it adds about 4-5HP assuming the 300ZX produced its maximum torque at the very same RPM as the Maxima's VG.

Summary: power valve doesn't help as much as you might think.
Summary of summary: everyone else was right, and your hesitation has nothing to do with the power valve, HOWEVER its failure to actuate could indicate that you have a vacuum leak elsewhere, preventing the surge tank from building vacuum in the first place.

our variable intake is not like the 6th gen one, which you may have been thinking of.

 

thanks all i replaces the powervalve actuator and no more hesitation.

 

After all that has been asked about?!

 

Don't forget to check your blinker fluid..

 

.... you can lead a horse to water, but you can't make him drink....

 

did you replace anything with it? or just the acutator? as in, no other maintainance of any kind was performed that could have possibly affected the hesitation? and you are sure that when the valve wasn't working, it was stuck open (normal position) right? not stuck closed (WOT low RPM position)..

i can't think that restoring the function of that part would have fixed the hesitation. You don't give antibiotics to someone with the flu... but you seem to have gotten rid of your flu when you took antibiotics... if you all know what i mean. It's like the solution you tried doesn't seem to lead to the cure... i dunno dude. keep an eye on it. 8lb/ft should not cause 'hesitation' unless something is leaking air usually. Did you mess with any plugs? Is your EGR connected to an auxiliary BPT valve or is it EGR temp-sensor driven?

 

vaccum leak at the actuator maybe?

 

Nope,i tested every aspect of the power valve system..I've ran the cars with the solenoid plug disconnected/with the vacuum hose disconnected with the hose plugged/also with the vacuum hose just laying there unplugged..both ve and vg ran as normal,no hestation/stumbling/nothing..

yeah,i have alot of spare time

 

how about the surge tank and one-way valve?

 

Nope,i didn't see any point in going past the solenoid/vacuum hose. i've read about a few members having removed their surge tanks from the system with no I'll effects,not sure on the one way valve.

I really thought just leaving the vacuum line off with with out it being capped off would make the car run rough,but it still ran as normal.

Basically,my point to all the testing was to confirm if the power valve actually gives you any noticeable power gain(the ole butt dyno),i honestly didn't notice any change in power in either car.Nor did i think i would be using the info to try and help someone that obviously has magical powers and can fix hesitation issues with the power valve.

 

i think you guys are taking the hesitation wrong. it was almost liek it was completely missing on all cylinders or as if someone paused the car

 

I think the mere fact that we all can report, with a motor in a good state of tune, very good fuel economy from a 3L motor designed about 15 years ago says a lot about the general efficiency and success of the overall design.

Sure there are components that could be fine tuned, but I suspect there will be some trade-off for any obvious benefit experienced - either extra cost or some parameter getting negatively influenced.

Since the projected torque gain is a mere 5% to be had from the switching of the intake tracts, my guess would be that the average arsedyno is just about guaranteed to not pick up any such change - especially on an auto where that effect is effectively masked to begin with by design.

Brian's suggestion is unfortunately the only sorta sensible thing imo - even though it cannot possible explain fully the original symptoms ..................... it is however such a damn pity that people asking for help and describing symptoms refuse to interact sensibly when asked and to stick to actual facts.

Perhaps those reliable Toyota connectors fitted, intermittently gets rejected by the Maxima on principle ............................ especially around 3500rpm and for a whole 5 seconds at a time

 

Connectors were all replaced as an attempt to fix this problem;

 

and you think a device that only modifies power 5% would cause all that?

well the open-ended vacuum hose wouldn't do anything, and here's why: at which time the solenoid actuates, you would be at half-throttle or higher. Vaccuum is basically nonexistant at that throttle setting. So the vacuum hose will not pull air thru the 1 way valve at that throttle setting... and when the solenoid closes, well it all gets closed off anyhow.

taking off the one way valve, however would cause a pure vacuum leak because the open ended hose would not be going through a solenoid-controlled valve, or a 1 way valve. If he has a leak down there, then there is a chance that when the solenoid fires, it causes a strange vacuum situation but it would have to be between the solenoid and the manifold, not any further up the line. So if you unplug the surge tank it should have a vacuum leak.... i can make a video. I know you guys love my videos;

 

ok here's what i have. sorry it's not great like i wanted it to be. i tried like hell to get the hose off the 1way valve but i couldn't with just 1 hand. point is... power valve DID NOT cause any sort of stumble on my car, and i have video proof.

i will say though that it sounded more agressive with the power valve attached and working, and that is not an illusion, just poorly captured by the microphone. In real life it sounded beefier when power valve worked.

http://s164.photobucket.com/albums/u...t=MVI_0283.flv