 | Home > Puma (Tdci) > Revs drop with stationary throttle |
 
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| custom90 Member Since: 21 Jan 2010 Location: South West, England. Posts: 20300  
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VCV likely. ⭐️⭐️God Bless the USA 🇬🇧🇺🇸 ⭐️⭐️
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9th Nov 2024 4:14pm |
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| Phillywilly72 Member Since: 29 Apr 2024 Location: Wiltshire Posts: 63 
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I heard they are troublesome so might be worth replacing anyway 👍
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9th Nov 2024 5:39pm |
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| Phillywilly72 Member Since: 29 Apr 2024 Location: Wiltshire Posts: 63
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Do I have to release the fuel pressure somehow before replacing?
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9th Nov 2024 6:06pm |
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| custom90 Member Since: 21 Jan 2010 Location: South West, England. Posts: 20300
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No, it’s quite simple just one electrical plug and two hex key bolts on it that mustn’t be over tightened, keep it clean.
You can tighten to the two stage torque tightening if you want to, it is likely all documented on here under the search feature. A ball ended hex key set (Allen key) is ideal. ⭐️⭐️God Bless the USA 🇬🇧🇺🇸 ⭐️⭐️ |
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9th Nov 2024 6:18pm |
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| Phillywilly72 Member Since: 29 Apr 2024 Location: Wiltshire Posts: 63
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Cool thanks will order now, heard that these need a relearning process via a diagnostic tool, is this right?
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9th Nov 2024 6:20pm |
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| custom90 Member Since: 21 Jan 2010 Location: South West, England. Posts: 20300
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No learn needed, it will self learn in time.
Some info might be useful: https://www.defender2.net/forum/topic92045.html I personally bought mine from PF Jones, but there are other suppliers too. I think BAS is one, and others out there. ⭐️⭐️God Bless the USA 🇬🇧🇺🇸 ⭐️⭐️ |
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9th Nov 2024 6:28pm |
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| andy63 Member Since: 30 Jun 2023 Location: north east Posts: 511
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I can remember blackwolf explaining to me when I was making a extension to my accelerator pedal that the revs can not be held steady using the accelerator unless the truck is moving..ie does not behave like a power take off control.. The revs will do as you say , they will decrease if you try and hold them by stopping movement on the accelerator...and I'm fairly certain that's hot or cold.. you would have to keep cycling the accelerator and the revs will rise and fall accordingly.. Hopefully he will be along to confirm or otherwise.. |
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9th Nov 2024 9:39pm |
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| blackwolf Member Since: 03 Nov 2009 Location: South West England Posts: 17353 
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Yes, if the vehicle is stationary the ECM will gradually close the throttle if you hold it steady to increase the engine speed. This is normal behaviour and should happen with engine hot or cold.
It's a nuisance since it makes it impossible to increase the engine speed when winching etc (unless you bought the unbelievably expensive hand throttle kit which included a reprogrammed ECM to allow elevated idle). |
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9th Nov 2024 9:55pm |
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| custom90 Member Since: 21 Jan 2010 Location: South West, England. Posts: 20300
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How much is it approx? An arm or a leg or worse much akin to the 1 piece genuine rear halfshafts I expect price wise?
Standard throttle issues seem a bit more common with the 2.2’s, but you never know it does happen. VCV is a lot worse when cold, mine when it was in its death throes would cut out, but act fine when warm, then do it again when cold and gets progressively worse. Rougher idle when stone cold, lack of power in top end gears. And it will cause revs to drop off when cold, unless revved which is why it will cut when at a junction for example when revs hit idle especially when cold. If it wasn’t for having a good idea what it is, it would be quite alarming and in the wrong situation dangerous, so any signs best to get it replaced if it is suspect. If the clutch switch is playing up, it normally has the opposite effect pushing the revs up and Rev hanging on gear change. ⭐️⭐️God Bless the USA 🇬🇧🇺🇸 ⭐️⭐️ |
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9th Nov 2024 10:13pm |
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| blackwolf Member Since: 03 Nov 2009 Location: South West England Posts: 17353
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The TD5 hand throttle was £1200 plus VAT or thereabouts twenty years ago, the TDCi is technically similar albeit not the same part so would likely have been a similar price.
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10th Nov 2024 8:19am |
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| andy63 Member Since: 30 Jun 2023 Location: north east Posts: 511
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Hi blackwolf... when you say gradually close the throttle...are you saying basically reduce fueling, or are you actually referring to the throttle as opposed to the accelerator.. I'm not nit picking , I'm just making sure I understand your comments..👍 On the winch control, I have only used the winch once under heavy load and even though I wasn't giving it any thought at the time , i assume the anti stall feature on the engine is operative at standstill and a load been applied to the engine..all be it a light load in comparison to normal driving.. |
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10th Nov 2024 9:07am |
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| blackwolf Member Since: 03 Nov 2009 Location: South West England Posts: 17353
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I don't know what mechanism the ECM uses nor the algorithm but it must reduce fuelling since that is the only control available. What I do know is that if you press the pedal and hold it absolutely steady after a few seconds the revs will drop, cycling the pedal will re-increase them but it is impossible to hold the revs elevated and steady in a stationary Puma by means of the pedal.
I assume that you refer to an electric winch (you don't specify). It is unlikely that the load on the engine via the alternator would be sufficient to load the engine significantly, but the anti-stall.regime (to maintain a constant engine speed irrespective of load) should deal with whatever load there is. The moment you apply any throttle input the anti-stall regime will exit of course. I don't know the details of the alternator performance but with a 100A alternator under ECM control it is quite likely that it can provide full output current at tickover in which case there is no merit in trying to elevate the engine speed at all when winching, there would be no gain. It's probably something that only went old folk would even think of doing. It would be interesting to measure the output at tickover under a significant (in the order of 150A or more) load to see just what it produces. The TD5 and TDCi hand throttle "kits" were only available through LR SVO and were aimed at vehicles with other PTO options such as me mechanical or hydraulic services (winches, access platforms, etc) where in order to run the hydraulic pump or service the engine must run at a higher speed. As an aside, it is interesting to reflect that nowadays vehicles which have significant stationary electrical loads, such as emergency services vehicles, are fitted with run-lock systems but not idle jacks, which I feel again is indicative of modern alternator performance. In reality, for electrical loads a hand throttle or idle jack simply is no longer necessary. |
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10th Nov 2024 11:14am |
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| andy63 Member Since: 30 Jun 2023 Location: north east Posts: 511
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Cheers blackwolf...yes, I'm on the same wavelength, and yes electric winch..
I would imagine a fully loaded winch would cause enough load on the alternator to alter revs a bit. Ive checked the current on the winch just spooling cable and even that was drawing 50 amps.. In my transit days ford provided a loop of wire that could be cut and used for a resistance ladder device you could build and plug in to control engine revs..if I remember correctly it had to be configured on fords ids as well to work.. It was a good anti theft device as well because when plugged in if you operated the accelerator it cut the engine..👍😁 |
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10th Nov 2024 11:54am |
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| Phillywilly72 Member Since: 29 Apr 2024 Location: Wiltshire Posts: 63
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Update- started from cold this morning and I had coughing and spluttering for a couple of mins, tried revving it and it felt like it was over fuelling with the revs dipping and black smoke out the exhaust with no response to asking it to increase revs. You guys still think they are symptoms to the faulty VCV still? Thanks
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10th Nov 2024 2:07pm |
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