 | Home > Technical > 2.4 Puma cold starting issues. |
 
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| custom90 Member Since: 21 Jan 2010 Location: South West, England. Posts: 20430  
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What you could do with is live rapid refresh rate voltage reading, I’m am sure that the voltage drop is significant. (Though the likelihood of viewing it and the problem / issue happening at the same time is slim).
That is, if it is voltage related of course). The strange thing is though, how it is sporadic as to when it happens. I had similar occur myself about a couple of weeks ago for no reason, it almost can make you feel like it won’t start at all for a split second. But then it does. It almost seems like a dead short, but isn’t. Is this the same sort of thing that others have had? Makes me wonder if it’s possibly some kind of ECU refresh, or repositioning of critical engine components, or checking of a components position. Sort of like say how a printer can occasionally program an alignment of the print head. $W33T $0U7H3RN $UG4R 🇬🇧🏴🏴🏴🇮🇪🇺🇸⛽️🛢️⚙️🧰💪 Last edited by custom90 on 16th Dec 2024 9:41pm. Edited 1 time in total |
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16th Dec 2024 8:29pm |
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| Ads90 Member Since: 16 Jun 2008 Location: Cots-on-the-Wolds Posts: 812 
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^ Yes, exactly this. Always has my heart-in-mouth when we’re running late and sounds like it’s not going to start!
The other time it often does it is in filling stations - warm engine, just filled & paid, come to re-start & it dies, sometimes triggering the alarm! Turn key off, wait a few seconds, try again and starts no problem. |
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16th Dec 2024 9:15pm |
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| BrickBox Member Since: 05 Oct 2021 Location: Wales Posts: 833  
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Have you checked around the injector area for any fuel leaks? Could possibly be the leak off lines cracked and causing a low fuel pressure on first starts. Get a torch in there and see if there is any fuel sitting in the rocker area.
Last edited by BrickBox on 16th Dec 2024 9:28pm. Edited 1 time in total |
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16th Dec 2024 9:24pm |
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| blackwolf Member Since: 03 Nov 2009 Location: South West England Posts: 17432 
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The frustrating thing is that there are many diagnostic tests one could do, and it should be possible to diagnose the cause with certainty very quickly, if it wasn't so intermittent and so completely unrepeatable!
The Puma starting circuit is very simple after all. (Edited for spelling) Last edited by blackwolf on 17th Dec 2024 9:50am. Edited 1 time in total |
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16th Dec 2024 9:27pm |
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| custom90 Member Since: 21 Jan 2010 Location: South West, England. Posts: 20430
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*accidental double post.* $W33T $0U7H3RN $UG4R
🇬🇧🏴🏴🏴🇮🇪🇺🇸⛽️🛢️⚙️🧰💪 Last edited by custom90 on 16th Dec 2024 10:08pm. Edited 1 time in total |
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16th Dec 2024 10:07pm |
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| custom90 Member Since: 21 Jan 2010 Location: South West, England. Posts: 20430
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Mine was up to temp too.
And yes, as Blackwolf stated, it will only do it whenever you least expect it as well. 
If the alarm happens to do off though (mine didn’t). Then that suggests to me that the voltage has had such a drop that it has dropped out of expected range that the alarm would like to see, that is likely due to current with the starter motor that is intermittent though. This brings me onto another idea, mines a 2.4 and I know Blackwolf’s has a 2.4 too. Are any of the rest of you getting it too with a 2.2? or just 2.4’s? LR did do some wiring changes to the 2.2, which might be to elevate starter motor voltage drop on cranking, 2.2’s are slightly up spec in wiring gauge. Though off the top of my head I can’t recall if this was just alternator to starter, or starter to battery, but also likely includes the ground as well. The larger the cable gauge, the voltage drop on cranking should be reduced and this then is an increase to the voltage that the starter sees on cranking compared to a smaller gauge cable. Which is good and as the voltage drop is reduced keeping the overall voltage on cranking kept higher, that will reduce the current draw on cranking. Higher voltage, means less current draw which is good within range. I think voltage drop on cranking with Pumas is a bit of an issue, and I think part of that is that LR fitted slightly smaller gauge primary power cables than they should have, as I mentioned 2.2’s upgraded slightly, and LR did that for a reason. I’m upgrading mine (the cables) soon, I will be able to see what voltages there is and what changes there is but these change dynamically anyway so accuracy in real world situations vary even down to things by ambient temperature. But high voltage drop on temporary cranking is common, even down to 9v temporarily and the current draw on that is high. A bad ground will have a similar effect, I’d rather see above 10.2v. You can of course have a load present prior to cranking, but I doubt that this is an issue to people talking of this, I mean if you had a winch active, a high load device such as inverter or an an audio amplifier that could do it if active at point of cranking, but on mine this is off as I have these items switched so they only come on when alternator and engine is running. Otherwise the HU will turn those on automatically if active, I have a switch so that the HU remote is only on when I want it to be, not just because the HU sends its signal. But it still happens, so it isn’t this but any extra load on cranking would exacerbate the effect of voltage drop on cranking, which is best to have all loads off at all times before cranking. Perhaps the ground path via transmission components and engine varies with temperature, back to the Alternator, overall it’s a solid reliable ground though, but there is a lot of current transfer especially cold cranking amps through there between the starter and the battery. $W33T $0U7H3RN $UG4R 🇬🇧🏴🏴🏴🇮🇪🇺🇸⛽️🛢️⚙️🧰💪 |
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16th Dec 2024 10:07pm |
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| Ads90 Member Since: 16 Jun 2008 Location: Cots-on-the-Wolds Posts: 812
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Yes mine’s a 2.4. It’s a problem I can live with, but would be nice to know why it happens. It didn’t when new, maybe started 3 or 4 years ago.
If you notice any difference when you change your cables, please report back? |
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17th Dec 2024 9:31am |
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| custom90 Member Since: 21 Jan 2010 Location: South West, England. Posts: 20430
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Will do - I expect with in the next few months.
It tends to be a bit more common in autumn, winter, and spring but not exactly defined to that. Again like you, I’m not too worried.  $W33T $0U7H3RN $UG4R
🇬🇧🏴🏴🏴🇮🇪🇺🇸⛽️🛢️⚙️🧰💪 |
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17th Dec 2024 7:13pm |
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