 | Home > Puma (Tdci) > My VCV Journey |
 
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| Joyosa Member Since: 13 Oct 2024 Location: Forcalquier Posts: 4   
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Thanks I will give that a try - did it once before and it showed a knackered injector.
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13th Oct 2024 10:56am |
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| andy63 Member Since: 30 Jun 2023 Location: north east Posts: 834 
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Is the vcv valve on the 2.4 dismantable..
I've seen vids where a small clip in the base allows removal of the valve plunger this but on the one on my 2.2 I'm pretty sure it's a sealed unit.. I think I'd have to destroy it to get at the plunger |
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13th Oct 2024 5:09pm |
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| MK Member Since: 28 Aug 2008 Location: Santiago Posts: 2508  
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Indeed it is. A bush mechanic would polish it with 1000-2000 grit or turn the plunger inside. Puma 110" SW
............................................................. Earth first. Other planets later |
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13th Oct 2024 5:15pm |
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| Minch90 Member Since: 15 Sep 2017 Location: Gloucestershire Posts: 248
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Denso DCRS300260 Available at mymotorworld.com for £55 with free delivery as of course I need another one!
As it is warm this time I will do the re-learn, can I do this with my BAS remap installed or do I need to flash back to factory instead? Don’t normally bother but thought I would this time to create some novelty to the endless VCV journey. Thanks in advance Dicky 2.4TDCI 90 - everyday brilliance S3 V8 Lightweight - in the garage being ignored #newchassistime S3 lightweight - 2nd car 24V fire risk with a full tilt and the windscreen down S1 80" - first car fun - 75mph in neutral downhill once #wobblesallround |
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24th Jul 2025 10:49am |
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| andy63 Member Since: 30 Jun 2023 Location: north east Posts: 834
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A link took me to this thread and I see I even made comment on it about a possible reason for 2.4 vcv failing mor frequently than the 2.2..
Anyhow since then I have done a bit more work on the vcv on my 2.2 and it answered a few of the questions that appear in this thread..so if you don't mind been bored ill cover the main points... On the 2.2 the vcv valve works on a duty cycled pwm supply.. its a negative duty cycle.. When running it is operating at about 15.5 volts and the signal frequency of the ground switched side is about 240 hz.. The pulse width are about 1.6ms and the ground switched side of that pulse varies according to demand.. In the first picture you see the vcv valve switching signal (in red) between 15.5 v and 0v.. because of the time base you don't see the individual pulses just a solid red mass... The blue trace is the fuel pressure signal .. And the black trace is the % duty cycle the vcv is operating at..  Click image to enlarge The next two show a zoomed in view of that red trace .. One looking at a portion when the vcv duty cycle is at about22%, and the next when its at about 31%.. The pulse width remain at about 1.6ms ,but the grounded portions when the solenoid is switched vary between 358 micro seconds at 22% .,and 514micro seconds at 31%.. This particular vcv is shut until it is powered , but i know some pumps on other vehicles that run a normally open valve when its switched off and operates in a reverse fashion when powered Click image to enlarge Click image to enlarge Anyway this might serve some purpose if anyone reads this thread in the future.. |
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6th Oct 2025 6:04pm |
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| andy63 Member Since: 30 Jun 2023 Location: north east Posts: 834
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Not that it makes a huge difference but the frequency of the vcv signal is in the order of 615 hz..not the 237 or whatever i said above.. I was looking at the blue trace signal by mistake😫
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6th Oct 2025 6:39pm |
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| andy63 Member Since: 30 Jun 2023 Location: north east Posts: 834
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Again just for information of anyone who hasn't looked at one of the common rail hp pumps of the type used on the defender, here's a few pictures of the bits and a brief explanation..
Think this unit was off a 2.4 transit.. As I said before I think one of the main differences between the 2.4 and 2.2 fuel systems is that the 2.2 has a positive pressure feed to the hp pump while the 2.4 relies on the small gear or vane pump incorporated into the body of the hp pumping unit.. Click image to enlarge So the inlet side of the pump supplies diesel to the suction side of the little gear type pump .. The delivery port of that pump feeds the inlet of vcv valve.. The vcv valve discharge side feeds the high pressure pumping plunger through a spring loaded non return valve incorporated into the head of the hp head .. There is a spring loaded pressure relief valve to limit the pressure of the little gear type pump.. and there is a minute passage that allows fuel to escape back into the pump body and into a return line..to ensure some cooling takes place I presume.. This photo shows the little spring loaded non return valve assembly that the gear pump supplies which is incorporated into the head of the hp plunger pumping unit.. Click image to enlarge |
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6th Oct 2025 7:21pm |
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| Minch90 Member Since: 15 Sep 2017 Location: Gloucestershire Posts: 248
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Took my last vcv apart (saw the scoring), and turned it into a key ring 👍 needed to drill out one hole to take a split ring
Click image to enlarge 2.4TDCI 90 - everyday brilliance S3 V8 Lightweight - in the garage being ignored #newchassistime S3 lightweight - 2nd car 24V fire risk with a full tilt and the windscreen down S1 80" - first car fun - 75mph in neutral downhill once #wobblesallround |
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8th Oct 2025 4:33pm |
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