Location of Suction Control Valve on a V9X Engine

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spiezzy

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hello to all I am trying to locate the Suction Control Valve on my 2011 STX550 Navara I have looked in my Workshop Manual and can not find it anywhere I would have thought it would have been in the engine control section but it is not unless it is under a different name any help would be much appreciated
many thanks
cheers Pete
 

Rumpig

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Not sure the 550 has a SCV , i've only heard it mentioned in relation to the 2.5 .
 

spiezzy

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thanks for the reply Rumpig mmmm I thought that might be the case but they do sell them https://www.ebay.com.au/itm/Nissan-...0-R51-V9X-3-0L-V6-STX550-SCV-008/113130710577

my reason for asking is my vehicle is blowing a bit of black smoke at the moment and someone suggested it might be the suction control valve it blows the smoke under acceleration but when cruising it disappears there is no loss of power and fuel consumption is around 9.5 to 10.5 (fully loaded with work stuff) suburban driving so I figure the injectors are Ok I have followed another STX550 and did not notice any smoke coming out of that just not sure what is causing it .
I had a Dyno Test done about 6 months ago and all seemed good with that but they mentioned that it was blowing black smoke under load and they were not sure why this is where the suction control valve came into play as the fella said it would be a good place to start and the cheapest
but I can not seem to locate one on this engine .
cheers Pete
 

MANNING

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If it's blowing heaps of BLACK trying running a decent injector cleaner thru it and also change your air filter.
I also suggest checking the horrible hose clamps on all the piping.
The original piping down to the intercooler is known to go super soft when hot and sucks in on itself under harder acceleration, may pay to replace with a hard pipe.
Lastly if you have a snorkel, check if your piping is clear - definetly a pain to do but better to be sure
 

Old.Tony

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The SCV (if yours has one, which is likely) sits on the top of the pump, at about 1 o'clock as you look at it from the front. It has a black electrical connector on it.

I wouldn't suspect the SCV for smoke straight away, as Manning says. I'd look at air filter, MAFS clean (it's in the air intake, unlike the YD25, yours is part of the air tube itself just outside the air filter). You MUST be careful with this. Do NOT EVER poke anything into the MAFS. You can spray it with electrical contact cleaner, but don't touch the innards, it's extremely sensitive (and expensive). If the MAFS is dirty, it will report the incoming air stream incorrectly to the ECU and the ECU will calculate fuel and boost incorrectly.

You could whack a Bluetooth OBD adapter (ELM327) in and watch your boost pressure. The V9X should easily produce 20psi of boost. If you're not getting that, and boost pressure doesn't rise fairly quickly when your engine revs climb, your turbocharger might be less responsive than it ought to be. This will probably be a bearing issue, and may show itself as a sloppy impeller/turbine shaft. This shaft shouldn't wobble, if yours does then your turbocharger may need replacing.

As Manning says, checking the air path is important. Also make sure your battery terminals are nice and clean as erratic electrical connections can cause problems which might result in commands to the turbocharger or fuel system not being as accurate as they ought to be.
 

spiezzy

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Thanks guys for the replies much appreciated I will check all that out I have got a snorkel fitted but it was only done 2 weeks ago and it was doing the same before then just went for a run up to Gosford and fuel is sitting on 9.3lp100k and ran like a treat up and back .
I will check the MAFS as that makes sense I am using a KLM air filter also have a Forge Industries intercooler with hard pipe conversion there was a small oil leak on this but has been fixes by replacing Orings .
the smoke only happens when I deck it once the revs catch up it goes away or if running up a steep hill and the gears are hunting for a second or 2 and labours in-between gear change just feel bit sere sorry for the people behind me they get a puff of smoke in there face .
 

spiezzy

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oh forgot to mention the boost pressure is at between 20 to 24 full boost and is quite reactive (have a boost gauge installed )
thanks again
 

bods

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As mentioned above, black smoke is due to excess fuel or lack of air. Once the turbo starts spooling, the air component is covered, it is before you start getting boost that you generally get smoke as the ecu increases fuel above the amount of air available. To get boost, you need fuel, too much fuel (rich mixture) produces black smoke, overfueling (white smoke) is unburnt fuel being pushed out the exhaust.

I don't really know what you mean by KLM filter, but if you mean K&N (one of the oiled ones), I would be buggering that off and fitting a paper one. The biggest issue (apart from letting fine dust through) with oiled ones is coating the MAF sensor in oil, which in turn gives the ecu either incorrect readings or they are delayed. If you have one of those filters in at the moment, try changing it out with a paper one, clean the maf sensor and disconnect the battery to reset the ecu, then drive it around a bit to see if the issue is still there.

Either that or follow 200 series landcruisers around and see what bad smoke is like haha

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spiezzy

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Hi Bods
yeh sorry I typed K&N filter but auto spell did it again and yep its the oiled version its due for service shortly so I will get a genuine one to put back in I gave the MAFS a clean last night with some circuit board spray but didn't touch the sensor it self as Old Tony suggested but didn't read do anything .
and yes its before the boost kicks in as soon as it has spooled up the smoke goes away
I have followed a couple of series 200 and yes they do chuff a fair bit of black smoke behind one yesterday coming up Bulli Pass in Wollongong
thanks for your help Bods Much appreciated
cheers Pete
 

bods

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The 200 series cruisers I have seen around perth lately remind me of the smoke screen that the bat mobile puts out haha.

Good luck getting it sorted out.

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spiezzy

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Ok the MAFS reading on my EDS is at idle 18.7 and under load at 100klm its around 107 I went up and got a genuine air filter today haven't popped it in yet but will do when i get home see how it goes hahah yep I know what you mean about the Bat mobile on the series 200
 

spiezzy

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Ok I have located the suction control Valve and its quite accessible on top of the high pressure fuel pump 3 bolts hold it down if the air intake hose and cold side plumbing of the intercooler and it should give you clear access to it I will remove it and give it a good clean the diesel mechanic here said it should be changed at about 1500000ks because it runs on very tight tolerances
 

spiezzy

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thanks for confirming that Tony he also said a slightly worn one can cause over fuelling and black smoke on sharp acceleration and said its the first place to start looking before injectors and such and much cheaper if that is the problem he also mentioned with my vehicle due to my fuel economy at 9.4 it is highly unlikely the injectors more likely MAFs or suction valve or a small crack in intercooler as there is no leaks in the plumbing anymore all nice and sealed .
 
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Old.Tony

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I don't think he's wrong. The SCV in the YD25 ran me about $280 but a set of injectors from Nissan is $4K, we found a set of genuine Denso injectors (to match my engine) for $1500 on eBay, still dearer than the SCV regardless. The MAFS could just be dirty and is easily cleaned but ONLY with electrical contact cleaner fluid (also sold at auto places as "MAFS Cleaner", same stuff). You take out the MAFs, spray this in the little hole and watch the black stuff pour out. When it runs clear you hold it for about 30 seconds before reinstalling to make sure all the cleaning fluid has evaporated.

You might also pop your intercooler off. It has two openings. Grab a can of petrol (who cares what kind, E10 is cheaper and just as good). Put your hand over one of the openings, with the intercooler resting on that hand, and pour about 100ml of petrol into the other opening. Put your hand on the other opening and turn the intercooler up the other way so the petrol runs down through the cores. You'll find it will build up pressure as you do this, release the UPPER hand (or you'll be sprayed with black shit that won't come out of the clothing, ask me how I know).

I do that 5 or 6 times until the petrol comes out showing some of the colour that it had when it went in and it does help.

Liqui Moly sell an injector cleaner that is pretty bloody good, too. It even helped prolong the life of my SCV there for a while, so give that a try - "Fuel System Treatment". You can also use the Diesel Purge, but that's a bit more fiddly (although it's also quite a lot faster than the one you throw in the tank).

Finally - if all else fails - you would have to start considering the turbocharger. It's cheaper than injectors too, and in my experience fails sooner than the injectors do. That would be time for analysis of the boost pressures being produced though, and an investigation into the boost control device. On my YD25, a vacuum produced by the engine is modulated by a Boost Control Solenoid (BCS) and this is then fed to the diaphragm of the actuator on the turbocharger. I've replaced my hoses twice, and the BCS twice, and now I don't use a BCS at all, I'm using a Tilix valve to control the boost. The Tilix valve works pretty well, to be honest, and is cheaper and more reliable than the BCS. There is no check engine light for a failed or faulty BCS in my car. Yours will very likely be different, as in 2011 or thereabouts they changed the turbocharger's vane control to electronic. Yours might be faulty - you won't know until someone with experience of that turbocharger takes a look.
 

spiezzy

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thanks once again Tony for your valuable advice it funny you mentioned the BCS as mine makes a funny buzzing sound and I have always felt it didn't sound right this is at idle and is intermittent
 

Old.Tony

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Does your car have a vacuum controlled vane actuator on the turbocharger?

If so, that could EASILY be the reason for smoke. Vacuum lines don't last forever, and the BCS is probably my most hated component in that engine bay.

There's one way to test it if you take care with the car ... connect the vac pump directly to the actuator (just remove the hose from the BCS and put that on the actuator). The turbo will provide FULL boost ALL the time now, so you have to be careful - it will boost like mad. If your smoke issue goes away, consider a Tilix valve as an alternative to the BCS, but be aware that the BCS is controlled by the ECU and will bring boost on earlier than the Tilix valve, which cna only react to the pressures present.
 

spiezzy

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hi Tony just have a quick question I got my hands on some Liqui Molly diesel purge and had a look on You tube to see how it is done but nothing on the V6 diesel I know there are sensors on the fuel filter and you need to put the 2 hoses into the bottle and let it run on the Liqui Molly run the engine will this upset the sensors or anything else ? what would you recommend cheers Pete
 

Old.Tony

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If you're really worried about mucking with the fuel filter (since I don't have a V9X myself I can't really say "pop this or that hose" and help you) there is an alternative that just takes a little more effort and time. You do have to trust your instincts on your fuel gauge though ...


Drive your car until there's about 5 litres of fuel left in the tank. Usually when my low fuel light comes on I've got 15 litres, and since my car (not towing) gets around 12LPHK, if I drove for another 7 litres worth (7 * 100/12) I'd drive for 60km ... then I'd pull over, pour the whole can into my tank, and drive off again for 30km (4 * 100 / 12 ). I'd then fill the tank. That's NORMAL driving. Not towing, not racing, and definitely not trying to park at Kotara Westfield 2 days before Christmas.



That minimises the dilution of the purge liquid, still runs it through the pump several times and you ought to notice the difference fairly quickly. Fill it up as normal and see how it goes.


In those formula, replace the "12" with however many litres per hundred km your car normally delivers.
 

spiezzy

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hi to all well I changed the SCV on the V9X and it took around 40 mins pretty straight forward I noticed in the old one on the connection plug inside it had diesel in it replaced with new Boach one and it seems to run a lot smother and much less smoke when flooring it (not that i do that all the time) put the old one under a micro scope and looked deep inside the plug and noticed a crack in the plastic so I would say it was ready to fail at some stage but all good now runs like a dream thanks again Tony for your help
cheers Pete
 
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