 | Home > Technical > 2.4 revving after some gear changes |
 
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| blackwolf Member Since: 03 Nov 2009 Location: South West England Posts: 17443   
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On my 2007 Puma, if you touch the accelerator pedal the AS is immediately rendered inoperative.
If, for example, you start climbing a hill on tickover (foot off the accelerator pedal), the AS will fuel the engine to ensure that the required torque is available to prevent the engine from stalling and maintain tickover revs, exactly as it should. If you then touch the pedal and make a very small pedal input, not enough to increase the engine speed significantly, the engine will stall as a result of the AS fuelling stopping. If you make a decisive pedal input, sufficient to drive away, the off it will go. The AS will not increase engine speed, just torque. If the hill is too steep to climb on tickover no matter how the engine is fuelled, the engine will stall. Idle Jack will increase engine speed, but is a wholly different thing. |
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12th Aug 2020 10:32am |
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| jst Member Since: 14 Jan 2008 Location: Taunton Posts: 8051  
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i need to do a quote Cheers
James 110 2012 XS Utility 130 2011 M57 bespoke Camper 90 2010 Hardtop 90 M57 1988 Hardtop |
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12th Aug 2020 12:09pm |
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| jst Member Since: 14 Jan 2008 Location: Taunton Posts: 8051
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yep agreed
err i disagree. i have just been out and tried it now in 3 pumas just to make sure i wasnt going mad. in low range up a hill, 1st (idel jack) 2nd and 3rd. so an applied load(hill), anti stall keeps vehicle moving at same pace, gentle press of accelerator and nothing changes, vehicle continues to move at same pace. Keep accelerating and when you input more fuel than the vehicle is receiving from AS engine speed increases as does pace. immediately come off the accelerator and still with hill load applied vehicle continues to climb at original AS pace.
correct as above so it doesnt turn it off like a td5. on a hill with td5 antistall (which is nowhere near as good) as soon as you touch the accelerator it defaults to tickover rpm fuelling and will stall unless accelerator is pretty much floored. i distinctively remember the presentation on AS at the time being different to the td5 as it works with human input. we may be splitting hairs here on terminology but for user you can accelerate through from light to heavy accelerator input and it doesnt stall on my 3 currently here, or the previous ones i have had or any of the LRE ones we instructed with. either way, i still get increase in engine revs when its not required. does it sometimes clutch in, sometimes clutch out. never done it on a cold engine and appears to do it after a light throttle application. Cheers James 110 2012 XS Utility 130 2011 M57 bespoke Camper 90 2010 Hardtop 90 M57 1988 Hardtop |
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12th Aug 2020 12:19pm |
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| blackwolf Member Since: 03 Nov 2009 Location: South West England Posts: 17443
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Interesting, I'll have a play when I next get the opportunity. I wonder if LR and HR behave differently, ie AS alone as opposed to AS and IJ.
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12th Aug 2020 12:40pm |
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| jst Member Since: 14 Jan 2008 Location: Taunton Posts: 8051
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i dont know on that. Idle Jack certainly working as it should be, and as you say a totally different function to AS. Cheers
James 110 2012 XS Utility 130 2011 M57 bespoke Camper 90 2010 Hardtop 90 M57 1988 Hardtop |
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12th Aug 2020 1:02pm |
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| jst Member Since: 14 Jan 2008 Location: Taunton Posts: 8051
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brake light switch is also something to look at apparently.
brake lights work. but just trying to remember if it does it after a brake press/slow down gear change or not linked to braking.... Cheers James 110 2012 XS Utility 130 2011 M57 bespoke Camper 90 2010 Hardtop 90 M57 1988 Hardtop |
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12th Aug 2020 2:04pm |
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| blackwolf Member Since: 03 Nov 2009 Location: South West England Posts: 17443
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A quirk of the TDCi is that there is an input from the brake lights to the ECM, and it can be shown that if the brake light fuse is blown the engine behaves differently when the clutch switch circuit is energised (this is mentioned in several other threads on this forum, although I suspect that this particular side-effect is unintentional).
The only other effect of the brake light input to the ECM that I am aware of, and probably the reason it exists, is if you brake whilst driving, for example to dry the brakes off after wading, you will find that the ECM cuts the throttle input to the engine after a few seconds and nothing you do with the loud pedal has any effect. It is a pain if you do need to dry the brakes, but I imagine is done because of the drive-by-wire nature of the accelerator to allow for the event of a major throttle pot malfunction mimicking a wide-open-throttle. |
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12th Aug 2020 2:38pm |
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| jst Member Since: 14 Jan 2008 Location: Taunton Posts: 8051
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Ok, cheers for info. Brake lights certainly working but will check all connectors. Cheers
James 110 2012 XS Utility 130 2011 M57 bespoke Camper 90 2010 Hardtop 90 M57 1988 Hardtop |
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12th Aug 2020 3:07pm |
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| Zed Member Since: 07 Oct 2017 Location: In the woods Posts: 3312 
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New take off’s are only £60-80. WARNING. This post may contain sarcasm. |
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12th Aug 2020 3:44pm |
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| jst Member Since: 14 Jan 2008 Location: Taunton Posts: 8051
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Thats not too bad, will try one off 110 first see if that cures it. Cheers
James 110 2012 XS Utility 130 2011 M57 bespoke Camper 90 2010 Hardtop 90 M57 1988 Hardtop |
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12th Aug 2020 3:48pm |
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| jst Member Since: 14 Jan 2008 Location: Taunton Posts: 8051
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accelerator pedal swapped this eve, will see how it goes next few days. Cheers
James 110 2012 XS Utility 130 2011 M57 bespoke Camper 90 2010 Hardtop 90 M57 1988 Hardtop |
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12th Aug 2020 8:30pm |
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| jst Member Since: 14 Jan 2008 Location: Taunton Posts: 8051
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fitted 110 acc. assembly and so far so good. Just the alternator/charging issue to sort out now! Cheers
James 110 2012 XS Utility 130 2011 M57 bespoke Camper 90 2010 Hardtop 90 M57 1988 Hardtop |
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17th Aug 2020 10:45am |
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