 | Home > Puma (Tdci) > My VCV Journey |
 
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| MartinK Member Since: 02 Mar 2011 Location: Silverdale (Lancashire/Cumbria Border) Posts: 2665   
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I thought I would share this as it may help others...
 Click image to enlarge This photo shows 3 VCV's: The one on the left is Original and was in the vehicle when I bought it new in 2011. The other 2 both exhibited different faults, which threw me on a journey to change other components including the Fuel Rail PRV and Sensor, the EGR, the MAF and MAP. In reality changing all these components probably wasn't a bad thing after 11 years and 56000 miles... It began in Autumn 2021. After a lay-up of my Defender during COVID, I was driving home, towing a trailer on cruise control on the M6, and the car lost power, slowed and eventually stopped on the hard shoulder. This began to happen more and more - most journeys. I cleaned, then changed the MAF and MAP and also did a full service inc Fuel Filter and Air Filter. I also ran a biocide fuel cleaner as the car had done very few miles through Covid. The problem remained. Eventually I changed the VCV on recommendation from Blackwolf and others. The initial problem disappeared, but was replaced by jerky running. Using my IID tool I could see that the fuel rail pressure was dropping (thread https://www.defender2.net/forum/topic80592.html ). I thought it can't be the VCV because I just changed it, so I swapped the Fuel Rail pressure Sensor, and then the Fuel Rail PRV. The problem remained. Still thinking it unlikely to be TWO failed VCV's I changed the EGR. I decided once again to change the VCV. I immediately developed a NEW fault. The Defender ran wonderfully. Cold starts were crisp and reliable. It ran well. BUT - if you stopped for just a couple of minutes (like fiiling with Diesel) - it would not start when hot! Thread https://www.defender2.net/forum/topic82418.html Again, I was going round in circles. Surely not THREE faulty VCV's??? This was getting expensive...and annoying! I put the original PRV and Fuel Rail Sensors back in, and that did nothing to change the symptoms, so I have kept them as spares. Throughout this I had no useful error messages on my IID tool. Having taken my Defender to a local Indie, they also could not fix/diagnose it! I decided to change the VCV again. FIXED After about 10 months, and all those parts, it seems I was just unlucky. I had bought all the VCV's from reputable dealers (like PFJones, Transit parts Online etc), but I now have 3 failed VCV's all with different fault symptoms! I should add that every time I changed a major component I did a re-learn on the IID tool. Anyway...the VCV is a really weak area on the 2.4 engine IMO, as are the diagnostics in that area. Next time it'll be the VCV I change first! Hopefully this may help others with similar issues... Defender "Puma" 2.4 110 County Utility (possibly the last of the 2.4's) |
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19th Nov 2022 1:34pm |
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| MartinK Member Since: 02 Mar 2011 Location: Silverdale (Lancashire/Cumbria Border) Posts: 2665
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I have wondered the same! I did buy off supposedly reputable dealers. Also I was very careful when fitting. It has certainly been an issue. Doubtful I would be able to return as "faulty" I assume... Defender "Puma" 2.4 110 County Utility (possibly the last of the 2.4's) |
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19th Nov 2022 3:23pm |
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| custom90 Member Since: 21 Jan 2010 Location: South West, England. Posts: 20299
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Perhaps your issue maybe the learning which is something that you don’t have to do.
Mine came from PF Jones, fitted straight in. Worked perfectly and that was it after initial time idling and then after about 20 miles things were just about perfect and that was it. Self learns in due course anyway. There are a few things that are in the WSM that are errors, and some things that are much more work than is needed. It’s a wonder it doesn’t say in there “remove engine to access transmission and clutch”… And as the learning process you did each time is something common to it, that maybe the issue and not the VCV’s themselves. Unless you have water in the fuel tank somewhere, I think there is a water trap that can be checked with the fuel filter or the actual fuel filter it’s self but it’s not something I have ever touched myself as the Puma fuel system is fairly complicated. The things you’ve mentioned such as diesel bug is one of the reasons why I run Millers Diesel additive permanently as it keeps fuel in a better condition. As does it help keep injectors and components such as the VCV in good nick. (Halfords with motoring club sub has good price on the additive - plus free MOT recently). Plus discount, plus free delivery. Many diesel techs have said that, the Millers does a really good job of keeping the engine internals and other components in really good condition. Runs smoother and with good power output too. You definitely did right by keeping everything really really clean though. As blackwolf mentioned before water kills VCV’s off rapid, and I’m pretty sure that happened to me after filling up with fuel somewhere. Best to be careful with fuel cans or anything like that too that no contaminated fuel or moisture is present or residue before filling. ⭐️⭐️God Bless the USA 🇬🇧🇺🇸 ⭐️⭐️ |
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19th Nov 2022 10:19pm |
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| hank Member Since: 12 Sep 2016 Location: South Wales Posts: 2295  
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I read on a transit forum that your reputable dealer sells cheap nasty VCV’s badged up as genuine DENSO.
I have bought VCV’s from there too and fallen foul to a dodgy VCV that lasts five minutes. Completely agree VCV is such a weak link. So many of us have spent hundreds chasing a gremlin only to find it was the pesky VCV all along. My original one lasted 12 years. Then I went through two in nine months > 110 XS Double Cab |
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20th Nov 2022 9:06pm |
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| Snowy90 Member Since: 23 Feb 2015 Location: Surrey Posts: 482 
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Very interesting post thanks , mine is running rough, very jerky, not so much loss of power and no codes coming up.
I did do the relearn wishing i hadnt bothered but makes me wonder if moisture is getting in somewhere, i think my breather is a bit old, when i brim the tank i get a few drips of diesel, so i dont fill it up anymore. i replaced the vcv with a denso unit from Autodoc, all was fine until coming back from a long run top Somerset at Christmas. I changed the MAP and MAf dint make any difference. I haven't started looking elsewhere for the issue as i am sure i have something else going on. How can you test/check if moisture is coming in? I would rather know before i replace another VCV 2.4 tdci |
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17th Jan 2023 5:41pm |
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| Smoeandco Member Since: 22 Jun 2021 Location: Sydney Posts: 9 
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@snowy you got an update here? Looking like I’ll have to replace my second VCV in 3 weeks. Idle is hellishly rough again and can’t even stop
At traffic lights without stalling |
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28th Jan 2023 9:23pm |
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| AndyS Member Since: 18 Aug 2012 Location: London Posts: 595 
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Change your fuel filter as well, VCVs are easily damaged by tiny bits of crap that get through.
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29th Jan 2023 12:40am |
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| Ianh Member Since: 17 Sep 2018 Location: Essex Posts: 1988
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^^^^^^^^^^^
And killed by any water that gets to the vcv, So change fuel filter and drain it regularly to ensure no water accumulates in the filter |
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29th Jan 2023 12:54am |
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| MartinK Member Since: 02 Mar 2011 Location: Silverdale (Lancashire/Cumbria Border) Posts: 2665
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I ran a couple of tanks with BIOCIDE (having heard about "diesel bug") and also changed the fuel filter.
My fuel filter had no signs of water - I usually drain the fuel from the old filter into a bottle and use it as a de-greaser on my motorcycle chain! It was a bit sludgy tho, hence the biocide... Defender "Puma" 2.4 110 County Utility (possibly the last of the 2.4's) |
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29th Jan 2023 6:24am |
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| hank Member Since: 12 Sep 2016 Location: South Wales Posts: 2295
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Where would people recommend to buy a genuine DENSO VCV? With least risk of receiving a knock off fake one > 110 XS Double Cab
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29th Jan 2023 12:32pm |
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| MartinK Member Since: 02 Mar 2011 Location: Silverdale (Lancashire/Cumbria Border) Posts: 2665
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Hank - PFJones seems to be respected... Defender "Puma" 2.4 110 County Utility (possibly the last of the 2.4's)
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30th Jan 2023 1:17am |
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| hornet Member Since: 04 Jan 2010 Location: Western Europe Posts: 361 |
Thank you very much for this experience report! I wonder if you can do a quality check of the valve yourself, apparently the manufacturers are not able to do/do not do this themselves. The valve ensures a constant pressure of the diesel that is sucked in? Can the faulty valves be checked for a common feature, e.g. whether the spring pressure is the same and whether the movement of the piston is trouble-free?
Apart from that, I wonder what the electrical connection is for, the valve looks purely mechanical to me. Does anyone know what happens when you unplug it? Click image to enlarge |
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30th Jan 2023 8:23am |
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| hank Member Since: 12 Sep 2016 Location: South Wales Posts: 2295
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The only thing I have noticed is that inside the open end of the unit there is a sprung plunger. If you operate the plunger of a faulty unit with a screwdriver I have found it to feel grainy/notchy compared to a new unit which feels smooth in its operation. > 110 XS Double Cab
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30th Jan 2023 10:58am |
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| custom90 Member Since: 21 Jan 2010 Location: South West, England. Posts: 20299
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Mine came from PF Jones, been perfect since. ⭐️⭐️God Bless the USA 🇬🇧🇺🇸 ⭐️⭐️
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30th Jan 2023 11:27am |
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