 | Home > Puma (Tdci) > irratic idle and clutch Q |
 
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| pannawonica Member Since: 21 Nov 2010 Location: Clackline Western Australia Posts: 568  
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My observation of the fuel use given your vehicle’s set up, does not seem excessive! This would not worry me one bit, but is typical. I have had a little idle wobble on a cold start, noticed when my departure was delayed. This at the time concerned me so I cleaned the MAP sender, the MAF was perfectly clean. As it did not return I discounted the VCV as an issue!
 your engine is still new and being diesel will need ten times that number of mile to free up! |
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9th Jan 2018 3:17am |
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| grafty99 Member Since: 15 Aug 2012 Location: North Devon Posts: 4784  
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The idle fluctuation when letting the clutch out in neutral when cold is normal. As the transmission is cold it will have extra drag and so will cause a slight drop. When warm there is less friction and so less fluctuation when releasing the clutch.
As for the fuel consumption. My 2015my 110 xssw was equally woeful. Also had done very similar mileage when I got rid of it. Apparently they improve with use and mileage but I didn't keep mine long enough to find out. I never had idle fluctuation though.... 2002 90 Td5 Station Wagon 1990 Vogue SE Triumph Tiger Explorer 1200 Td5 90 Thread http://www.defender2.net/forum/topic50767.html Tdi 110 Thread https://www.defender2.net/forum/topic69562.html RRC Thread http://www.defender2.net/forum/topic54492.html Instagram http://www.instagram.com/george_grafton |
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9th Jan 2018 9:29am |
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| Jerry Member Since: 13 Nov 2015 Location: Cardiff Posts: 168 
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thank you for the replies.
^^^^If you have time, could you please explain in lay terms why a clutch released out of gear (and the vehicle is stationary) affects the idle when cold. I would just like to understand and can't get my head around the transmission having friction which would affect this (sorry - I don't have a clue). is it the same as having a bit of load, as if it was in gear..? Also, I noticed that there is a slight fluctuation in idle when very cold when I put on the heated screens - is that normal as well? I presume that may be my battery is low (I do short runs mainly) causing a surge in the primitive software or something? thank you. |
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10th Jan 2018 12:21am |
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| blackwolf Member Since: 03 Nov 2009 Location: South West England Posts: 16865 
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Turning the heated screen on will add a substantial electrical load to the alternator, which makes the alternator harder to turn, which increases the load on the engine, which slows the engine momentarily until the software in the ECU notices that the idle RPM have dropped and adjusts to compensate.
A similar thing can happen with the transmission. With the clutch in, the engine is turning the input shaft, primary gear cluster, and layshaft in the main gearbox. When cold, the lubricant is relatively thick and spinning all these gubbins requires more power than when the box is at running temperature. When you throw the clutch out by pressing the pedal, you remove this load from the engine and the engine may speed up momentarily until the software in the ECU notices that the idle RPM have increased and adjusts to compensate. There is also a clutch switch fitted to all TDCi Defenders which tells the ECU when the clutch is depressed. Its function and effect on the ECU software varies according to engine and software revision, but it may also cause engine speed fluctuations when the pedal is pressed. Last edited by blackwolf on 10th Jan 2018 1:37pm. Edited 1 time in total |
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10th Jan 2018 9:25am |
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| Jerry Member Since: 13 Nov 2015 Location: Cardiff Posts: 168
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Great explanations. thank you very much. very helpful.
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10th Jan 2018 10:22am |
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