 | Home > Puma (Tdci) > My VCV Journey |
 
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| blackwolf Member Since: 03 Nov 2009 Location: South West England Posts: 17353   
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Not quite. The valve regulates the flow of fuel from the LP stage of the pump to the HP stage, and by doing so regulates the pressure in the common rail. It is the only mechanism by which the ECM can control the fuel rail pressure (FRP), and is therefore being modulated constantly to adjust the FRP. It is for this reason that quite often the first indication of a VCV problem is that the engine fails to adjust correctly to a sudden change in fuel demand, either an increase or decrease, for example misfiring when you put your foot down. You may in the early stages of failure find you can accelerate gently but not quickly. In many ways the VCV performs a function which is conceptually similar to the jet in a variable-jet carburettor such as an SU or Stromberg. If it doesn't work correctly, it also creates a very similar misfire to an SU with a sticky piston or a Stromberg with a leaky diaphragm (although I don't sppose many on here remember carburettors now, let alone SU or Stromberg carbs)! 
It would be interesting to stick a scope on the supply to the VCV and see how the ECM actually controls it, but this is something which is always on tomorrow's "to do" list not today's. |
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30th Jan 2023 1:32pm |
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| hank Member Since: 12 Sep 2016 Location: South Wales Posts: 2295 
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Petrols use a mechanical regulator to maintain fuel rail pressure. It is so much simpler! Thought I suppose we are talking significantly less pressure so it is understandable why it's done this way on a diesel > 110 XS Double Cab
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30th Jan 2023 3:49pm |
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| hank Member Since: 12 Sep 2016 Location: South Wales Posts: 2295
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Can only see PF Jones' own brand on their website at £48? How do you find the DENSO branded ones?
https://www.pfjones.co.uk/denso-suction-co...fp110.html > 110 XS Double Cab |
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30th Jan 2023 3:57pm |
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| MartinK Member Since: 02 Mar 2011 Location: Silverdale (Lancashire/Cumbria Border) Posts: 2665 
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Hank I thought that was a Denso one, it says so in the title??? Defender "Puma" 2.4 110 County Utility (possibly the last of the 2.4's)
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31st Jan 2023 8:00pm |
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| hank Member Since: 12 Sep 2016 Location: South Wales Posts: 2295
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You’re right it does but then on the website it says manufacturer: PF Jones and it’s in a white PF Jones box rather than a brown Denso one? I will phone them tomorrow and check. > 110 XS Double Cab
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31st Jan 2023 9:08pm |
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| custom90 Member Since: 21 Jan 2010 Location: South West, England. Posts: 20299
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I just bought the standard one supplied by PF Jones, it came in a genuine Nissan parts box with correct part numbers on.
I just fitted it and it was absolutely fine. So long as the part no checks out it’s the correct part, it must be a shared part on some Nissans as well? I would guess Xtrails or Navaras or something like that. It’s the same with many Ford parts that can be used, mines got a Ford transit water Pump, Ford MAF and the Transit 4x4 clutch. Bosch MAP sensor etc etc. Many LR parts are farmed out to another manufacturer anyway and relabelled or repackaged. LR Gen parts, whilst some are the best it’s not always the case that it is. For example I’m impressed by Ashcroft Transmissions parts as an example where quality is impeccable. ⭐️⭐️God Bless the USA 🇬🇧🇺🇸 ⭐️⭐️ |
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31st Jan 2023 11:37pm |
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| hank Member Since: 12 Sep 2016 Location: South Wales Posts: 2295
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Yeah I get that it's a fairly standard part used across platforms, just want to be sure that it is a genuine DENSO unit and not some crap chinese conterfeit.
This is well reported online - I posted about it here https://www.defender2.net/forum/topic85567-29.html I fitted a "genuine DENSO" VCV last month... The engine struggled to run at all and the ECU would not complete a relearn with it. I refitted the existing faulty VCV and it relearned straight away. It is still faulty though and needs replacing. > 110 XS Double Cab |
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1st Feb 2023 10:13am |
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| hank Member Since: 12 Sep 2016 Location: South Wales Posts: 2295
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Called PF Jones. They are not genuine Denso, they are "plain box made in the same factory"
The photo on the website shows PF Jones moulded into the plastic  Click image to enlarge Click image to enlarge > 110 XS Double Cab |
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1st Feb 2023 10:32am |
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| Retroanaconda Member Since: 04 Jan 2012 Location: Scotland Posts: 2638 
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Aye right, we’ve all heard that one before |
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1st Feb 2023 7:00pm |
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| Bluest Member Since: 23 Apr 2016 Location: Lancashire Posts: 4206 
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Yes, as soon as he said that, I'd be looking elsewhere. Just like the tyre fitters telling you the Triangle Ditchfinder 5000s are secretly made in the Michelin factory. 2007 110 TDCi Station Wagon XS
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1st Feb 2023 7:27pm |
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| Bluest Member Since: 23 Apr 2016 Location: Lancashire Posts: 4206
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Autodoc listing the Denso one for £60 in stock. There's a number of other brands on their to choose from. Their delivery times are herrendously long, but they are a ligit retailer. 2007 110 TDCi Station Wagon XS
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1st Feb 2023 7:31pm |
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| hank Member Since: 12 Sep 2016 Location: South Wales Posts: 2295
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Ordered one from LR Parts, cost £81 delivered. Expensive business when they only last five minutes
Hopefully a genuine one will last a bit longer https://www.lrparts.net/lr009837-fuel-vapo...ngine.html > 110 XS Double Cab |
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2nd Feb 2023 2:32pm |
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| hank Member Since: 12 Sep 2016 Location: South Wales Posts: 2295
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VCV arrived... This must be the fifth one I've had over the last couple of years and I have to be honest I've not seen one packaged like this before. This one comes with instructions and two 'alignment pins' to guide the VCV into position (seems overkill?)
The part number is LR009837G - does the G signify genuine? The box does say DENSO CORPORATION on it so that is reassuring although it is just a printed sticker! There are no DENSO markings on the VCV itself The plunger on this one feels smooth in its operation which is a good sign. Time will tell on longevity I suppose. The previous one I had was gritty in its operation out of the box. Click image to enlarge Click image to enlarge Click image to enlarge Click image to enlarge > 110 XS Double Cab |
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2nd Feb 2023 4:44pm |
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| custom90 Member Since: 21 Jan 2010 Location: South West, England. Posts: 20299
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Bear in mind with Autodoc that you’ll have a bit of a wait, whilst everything was okay when I bought my clutch from there it did take the best part of two weeks which I thought was quite a while these days.
Smaller item likely to be quicker though. ⭐️⭐️God Bless the USA 🇬🇧🇺🇸 ⭐️⭐️ |
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2nd Feb 2023 5:49pm |
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