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Re: Power Valve Actuator (PVA) Mod

Posted: 28 Oct 2013 19:50
by Blitzpatrollie
As far as I know this valve is there to limit the amount of initial torque put on the gearbox and diffs, and I can see why that is, you really have to nurse it out of the blocks otherwise you spin the wheels. Really loads of torque. Would make sense to me that Nissan put this there to protect the gearbox/diffs, which they would have to guarantee for a length of time/distance from new.

Re: Power Valve Actuator (PVA) Mod

Posted: 28 Oct 2013 21:53
by Gerrit Loubser
No' there are much cheaper ways of limiting engine torque on an electronically controlled engine than fitting an expensive valve and actuator to the inlet system.

As far as I know, the valve simply adjusts the effective length of the inlet manifold to provide lengths that are closer to the optimum, both at low and at higher engine speeds. As such it would not make sense to fiddle with the system unless it is malfunctioning. Think about it: why would Nissan spend money to add a feature to the motor that makes it worse when they were not forced to do so?

To the guys who have fiddled with the operation of the variable induction system: Are you sure that you have actually made things better? Have you measured this improvement properly? Are you sure it is not the placebo effect at work?

Re: Power Valve Actuator (PVA) Mod

Posted: 29 Oct 2013 05:03
by JohnBoyZA
"Are you sure it is not the placebo effect at work?"

Man I need to find a dictionary... :think:

Loving this thread, but not sure where it's going :wink:

Re: Power Valve Actuator (PVA) Mod

Posted: 29 Oct 2013 07:10
by Coltenator
Did this mod +- 3000km back and found no real improvement on fuel consumption.
There is a slight improvement on bottom end torque , but nothing to go bonkers about.
I found the cruise control bypass mod was more helpful and really works well , especially while towing in manual mode in 4th gear
and really easy to do :mytwocents:

Re: Power Valve Actuator (PVA) Mod

Posted: 29 Oct 2013 08:48
by Wheels
Did this mod and had it on for about +- 6000km and found no real improvement on fuel consumption. Changed back to the original setup.
There is a slight improvement on bottom end torque but no real reason to do the mod.
I think on the manual box you might see more change in behavior. The auto box seems to soak up the differance and no fuel saving there.

Re: Power Valve Actuator (PVA) Mod

Posted: 29 Oct 2013 21:53
by Tinus lotz
It changes the lenght of your inlet manifold that only happens after about 3.500 rpm but we dont normally drive there

Re: Power Valve Actuator (PVA) Mod

Posted: 07 Nov 2013 20:55
by Blitzpatrollie
Hi guys,

Okay, my fuel consumption was right down to 3.9km/l, so reversed the mod. @Gerrit, no placebo effect there, definite loss of low end torque on going back to pre-mod. I still figured that the vehicle is heavier on juice than it should be, so I cleaned the MAF sensor with Electrokleen (Spanjaard), and on Monday did a trip from Nelspruit to Kwamhlanga and back, and over 550km, recorded fuel consumption of 6.46km/l, which I think is great considering where I was.

Another thing, after my major service at Nissan Nelspruit, I was told that my Oxygen sensors are sharp (I specifically asked them to test them for me). So today I was looking for a fuel leak (which there was, on the subtank hose), so thought i'd check on youtube how to test an oxygen sensor. So I plucked them out and tested myself, both of em stone dead. The one sensor's wires had NO insulation left so was not sending the ECU any voltage. And the %&$#ers at Nissan reckon its all good.

So I went over to Bosch Diesel, and bought 2 universal senssors for R590 ea incl VAT, and installed them. Noticably smoother on idle, haven't test driven yet, but I think surely the engine was overfuelling to compensate for the lack of voltage sent to it from the sensor. Time will tell and I'll let you know. I'll post a new thread explaining how the universal sensor differs from the one that was in.

Anyway, not to get off topic, my point here being that I did the PVA mod in the hope of saving fuel, but there are other things to check, MAF, O2 sensors etc. DONT TRUST YOUR STEALER IF THEY TELL YOU THE SENSORS ARE OKAY!! CHECK THEM YOURSELF!!

The link to the vid that demonstrates how to test the O2 sensor is here:



Cheers!

Re: Power Valve Actuator (PVA) Mod

Posted: 08 Nov 2013 04:44
by Clem
Interesting - thank you. Let us know what happens with your fuel consumption.

Re: Power Valve Actuator (PVA) Mod

Posted: 21 Aug 2017 17:51
by JoshJ
Hi Gaven,

What was the outcome of the sensor change?

I was just chating to Tinus and them about the huge surge in power once you go over 3500rpm and we eventualy ended up on this topic. So I just read the thread. And was wondering on your sensor outcome.
My Patrol idles a bit rough. Might be those sensors?

Re: Power Valve Actuator (PVA) Mod

Posted: 14 Sep 2021 10:59
by Spike
Old thread resurrection. Can of worms continuation.

I just did this mod to my 4.8 auto on the spur of the moment. VERY noticeable improvement in reversing, no longer feels like I'm riding a manual with a slipping clutch. General driving seems to be better off idle, the lethargy is gone.

I'm working on both a mountain and the dunes in the coming week so I'll see if there are any negative effects but right now I'm very happy with the reverse gear fix.


The way I see it the OEM system is (for want of a better description) a three way system. It is open at idle (1), then closes when accelerating (2), then opens again at around 3500rpm depending on parameters (3). Going from idle to accelerating is where the problems lie. The DIY mod fixes that aspect but then deletes the gain at top end (makes it a one stage system). The ideal would be figuring out a way to make it a two stage system, starting from a closed position at idle but still opening at top end (closed at idle and accelerating, then open at 3500rpm upwards)

Edited twice to reword the 1, 2, and 3 stage blurb to try get my point across better