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phillips321



Member Since: 16 Dec 2021
Location: UK
Posts: 92

2005 Defender 110 2.5 TD DCPU Belize Green
TD5 cruise control aggressive throttle control
Hi all,

Have done a cruise control mod to my TD5 but it’s not really a smooth ride. It feels as though when the speed drops below the set speed it aggressively tries to speed up. Then it passes the set speed and comes completely ‘off the gas’ and it engine breaks hard. Before completely looping this over and over. On flat roads it’s most noticeable, climbing hills it’s almost not there.

Any idea what could cause this?

Could play/slop in my drive line cause this?

Thanks in advance
Post #951607 4th May 2022 8:33pm
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freddie206



Member Since: 18 Oct 2015
Location: Skipton
Posts: 85

United Kingdom 2006 Defender 110 Td5 HT Belize Green
I also fitted the Discovery cruise control to my Td5 and have the same “symptoms” as you describe. From what I’ve read/learnt on here it behaves like that because the cruise control built into the ECU is fairly rudimentary. As far as I’m aware there’s nothing that can be done but I’d happily be corrected.
Post #951611 4th May 2022 9:21pm
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blackwolf



Member Since: 03 Nov 2009
Location: South West England
Posts: 16808

United Kingdom 2007 Defender 110 Puma 2.4 DCPU Stornoway Grey
My Disco2 does this, it is really a very rudimentary system.

There is a road near here which consists of a series of humps and dips. Using the cruise control along it is both hilarious and disturbing, since when you go up a hump the vehicle slows, then accelerates as hard as it can, flies over the top creating a feeling of weightlessness, starts to rocket down the other side and spontaneously comes right off the power at about the time you get to the bottom of the dip causing it to slow right down just in time for the cycle to repeat. It is a very strange ride, and one which people would pay for at a fairground.
Post #951622 4th May 2022 11:06pm
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Penfold_6290



Member Since: 22 Sep 2021
Location: Dorset
Posts: 272

United Kingdom 2002 Defender 110 Td5 CSW Epsom Green
Same here I'm afraid. Very hard to get a nice steady speed unless the road is very flat, the faster you go the worse it gets.

It is better than nothing but does take some managing.
Post #951629 5th May 2022 7:33am
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Intercept



Member Since: 27 Feb 2017
Location: Suffolk
Posts: 587

United Kingdom 2002 Defender 110 Td5 Black LE Java Black
Mine is the same. The surge/backoff depends on RPM - if it's within the turbo's high boost range then it's worse, but at low RPMs it is good. I'm wondering about talking to my remap guy at Empire to see if it is possible to detect the CC engagement and dial back the boost.
Post #951639 5th May 2022 10:04am
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phillips321



Member Since: 16 Dec 2021
Location: UK
Posts: 92

2005 Defender 110 2.5 TD DCPU Belize Green
I’ve noticed it’s much worse since my stage2
Post #951641 5th May 2022 10:14am
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lightning



Member Since: 23 Apr 2009
Location: High Peak, Derbyshire
Posts: 2159

United Kingdom 
Hmmm.....l have the two button cruise control on my TD5 and don't experience this issue, except when you try to use it at low speeds, where it can struggle to maintain a steady speed. On the rare occasions l want to use it at under 40mph l find it works better in 4th gear than 5th

At motorway speeds it's fine, l've used it continuously for hours driving to Scotland. My TD5 has a mild remap around 25% more power and torque l was told.

My cruise control is the "wiring harness and two buttons" Nakatanenga one, that you can actually make yourself.
Post #952233 11th May 2022 8:03am
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roel



Member Since: 08 Aug 2009
Location: Lelystad
Posts: 2039

Netherlands 2003 Defender 90 Td5 PU Caledonian Blue
I have a tuning box and I have it wired that way it only works at full throttle and not if CC is regulating the speed.
So it doesn't feel harsh at all. OK it is slow to react. My only hills are fly-overs so there I feel I loose speed and when I am almost on the top it is back at the set speed and when it goes down again I am low on speed again where it gets flat.
That is a bit strange for a car behind me but I don't worry to much about that. Roel

1984 90 2.5 na Diesel - RR V8 (1994-2001)
1997 Camel Trophy Discovery 300TDI (2001-2009)
2005 G4 Discovery III 4.4 V8 (2008-2018) It's gone but it still hurts.
2003 90 Td5 (2009-now)
Post #952237 11th May 2022 8:26am
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MadTom



Member Since: 10 Sep 2013
Location: Olomouc
Posts: 556

Czech Republic 1999 Defender 130 Td5 HCPU Baltic Blue
It is possible to change cruise controll parameters the "same way" as remaping ECU for more power.
I have cruise control in Discovery 2 and Def 130 - both with some more power, both on the heavy side and it works, but I use it mainly on highways for cruising around 100 km/h during long trips. The switch on is not super smooth, but when switched with gently manipulation of throttle (slow release of pedal), it works nice. "Drobek" = The Small One - Discovery 2, "Blufínek" = The Blue Thing - Defender 130, and for me at least Ford Mondeo Smile
Post #952240 11th May 2022 8:36am
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blackwolf



Member Since: 03 Nov 2009
Location: South West England
Posts: 16808

United Kingdom 2007 Defender 110 Puma 2.4 DCPU Stornoway Grey
phillips321 wrote:
I’ve noticed it’s much worse since my stage2


I imagine that this is simply because when the CC tells the ECU to accelerate with 80% throttle (or whatever percentage it uses) there is more power available so the vehicle accelerates faster. It will then similarly be much more noticeable when it comes off the power.
Post #952291 11th May 2022 5:04pm
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lightning



Member Since: 23 Apr 2009
Location: High Peak, Derbyshire
Posts: 2159

United Kingdom 
l think it must be possible to change how the cruise control works in the software because mine is really smooth in operation even on flat roads or roads that go up/down.

When it accelerates in cruise it comes
on the power gradually rather than flat out. One exception is when pressing the "resume" button, again the power builds rather than full power immediately, but it seems to be able
to summon up more acceleration than l can get out of it with the gas pedal !!

l can't explain the uneven operation of the cruise control on your Defenders, except to say that mine doesn't do it.
Post #952300 11th May 2022 5:33pm
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